Burden of hypertension in The Gambia: evidence from a national World Health Organization (WHO) STEP survey

Burden of hypertension in The Gambia: evidence from a national World Health Organization (WHO)... Abstract Background Non-communicable diseases are increasing in sub-Saharan Africa and are estimated to account for 32% of adult deaths in The Gambia. Worldwide, prevalence of hypertension is highest in the African region (46%) and a very high proportion is undiagnosed. This study examined diagnosed and undiagnosed hypertension in The Gambian adult population. Methods Data were collected in 2010 from a nationally representative random sample of 4111 adults aged 25–64 years, using the World Health Organization STEPwise cross-sectional survey methods. Analyses were restricted to non-pregnant participants with three valid blood pressure measurements (n = 3573). We conducted gender-stratified univariate and multivariate regression analyses to identify the strongest sociodemographic, behavioural and biological risk factors associated with hypertension. Results Almost one-third of adults were hypertensive; a high proportion were undiagnosed, particularly among men (86% of men vs 71% of women with hypertension, P < 0.001). Rural and semi-urban residents and overweight/obese persons had increased odds of hypertension. Compared with urban residents, participants from one of the most rural regions had higher odds of hypertension among both men [adjusted odds ratio (AOR) 3.2; 95% CI: 1.6–6.4] and women (AOR 2.5; 95% CI: 1.3–4.6). Other factors strongly associated with hypertension in multivariate analyses were age, smoking, physical inactivity and ethnicity. Conclusions Rural and semi-urban residence were strongly associated with hypertension, contrary to what has been found in similar studies in sub-Saharan Africa. Intervention to reduce the burden of hypertension in The Gambia could be further targeted towards rural areas. Hypertension, Gambia, sub-Saharan Africa, WHO STEP survey, health examination survey Key Messages One-third of the adult population (25–64 years) in The Gambia are hypertensive and a high proportion of these are undiagnosed. Unlike previous studies in sub-Saharan Africa, hypertension was more prevalent in rural than urban residents in The Gambia. There should be periodic screening of blood pressure, especially among rural residents. Overweight and obesity were strongly associated with hypertension, and hence preventive efforts should be directed to diet and socio-cultural factors that facilitate the increasing burden of hypertension. Introduction Globally, there is an increasing epidemiological transition in the disease profile from infectious diseases and nutritional deficiencies to non-communicable diseases (NCDs), but the burden of NCDs is higher in sub-Saharan Africa (SSA).1–8 NCDs account for 70% of global deaths annually; 80% occur in low- and middle-income countries.9 Countries in SSA are also grappling with the double burden of communicable and non-communicable diseases.10,11 Less than 3% of global aid is directed towards NCD prevention and control.12 Hypertension is a global health challenge, with a higher burden in SSA. In 2008, the worldwide prevalence of hypertension among adults aged 25 years and above was 40% and was highest in Africa (46%).13 Of even greater concern, a large proportion of hypertension in Africa is undiagnosed.5,14 Although hypertension is the commonest modifiable risk factor for stroke and other cardiovascular diseases (CVDs) in Africa, its prevention and control are not prioritized.5,15 Early detection and treatment are crucial for the effective control of hypertension and the prevention of complications. NCDs are increasing in The Gambia, the smallest country on mainland Africa, with a population of 1.8 million. NCDs account for around 32% of adult deaths.16 A study using verbal autopsy in rural Gambia also found that 38% of deaths in 1998–2007 were associated with NCDs.17 Studies on hypertension in The Gambia are very limited; few used population-based health examination survey data. A population-based survey on hypertension (part of a nationwide survey on blindness and low vision in 1996) reported a prevalence of 10% (blood pressure ≥ 160/95 mmHg) among adults aged 15 years and above, and 24% above 140/90 mmHg.18 More than half of the participants in that study were surveyed during the holy month of Ramadan, which can influence the anthropometric and blood pressure (BP) measurements. A related study showed that people in The Gambia with a family history of hypertension had higher BP, cholesterol and uric acid than those without that family history.19 Hypertension poses both public health and economic burdens on individuals, families, governments and society.20 Many governments and families in SSA, including The Gambia, will not cope with this increasing burden coupled with the existing burden of infectious diseases. This can pose a barrier to poverty alleviation, hindering attainment of the United Nations Sustainable Development Goals.7,9,21,22 Despite this, there is very limited up-to-date information on the burden of hypertension and associated risk factors in The Gambia. This study aimed to examine diagnosed and undiagnosed hypertension in Gambian adults. Methods Study setting, design and sample This paper is based on secondary analysis of data from the WHO STEP survey conducted among adults aged 25–64 years from January to March 2010 in The Gambia.23 The survey is the most recent nationally representative, population-based, cross-sectional health examination survey in The Gambia, and the only one conducted based on the WHO STEPwise approach for NCDs. The WHO STEPwise approach, otherwise known as WHO STEPS, is a standard population-based health examination survey approach to NCD surveillance. Data are collected in up to three steps.24 Step one uses interview-based questionnaires, collecting information on sociodemographic and behavioural risk factors as well as history of diabetes and hypertension. Step two involves physical measurement of weight, height, waist circumference, blood pressure (BP) and pulse rate. (Biochemical measurement of fasting blood glucose and cholesterol is conducted in step three, not done in The Gambia.) Survey participants were selected using a multi-stage, stratified sampling technique based on the 2003 population census. The Gambia is divided into eight local government areas (LGAs) and 4098 enumeration areas (EAs). The LGAs served as sampling strata; 264 EAs were selected across the country by simple random sampling. The number of EAs selected per stratum (LGA) was proportional to the stratum population. From each selected EA, 20 households were selected by simple random sampling. One eligible participant was enrolled in each selected household, using the Kish method. The target was 5280, but 4111 responded (77.9% response rate). The age, sex and geographical distribution of the participants were similar to those of the 2003 and 2013 census reports; 232 pregnant women were excluded because of the impact of pregnancy on anthropometric and BP measurements. The analytical sample was limited to participants with three valid BP measurements (n = 3573). Research instrument and data collection Personal digital assistants (PDAs) programmed with eSTEPS software, an electronic version of the WHO STEPwise paper-based questionnaire, were used for data collection. eSTEPS has an automatic skip pattern and allows errors to be checked as the interview is ongoing, so is less prone to errors compared with the paper-based version. Data were collected by health staff drawn from all regions. Sampled participants were visited at their home for both interview and physical measurements. Eligible participants not reached after several visits, and those who declined to participate, were not replaced. BP was measured three times in the sitting position using an automated sphygmomanometer. Ethical approval was obtained from the national ethics committee; participants gave either verbal or written consent. Definition of variables Outcome variables Definitions of most of the variables were based on the WHO STEP criteria.24 The mean of the second and third BP readings was used in analysis. The main outcome variables in this study are: total hypertension, defined as measured raised BP (systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg), and/or self-reported hypertension (as diagnosed by a doctor or health professional, which included all participants receiving treatment); undiagnosed hypertension, the proportion of participants with total hypertension not aware of their status before the survey. Covariates These comprised sociodemographic, behavioural and biological risk factors including age, ethnicity, education, residence, fruit and vegetable intake, physical inactivity, smoking, alcohol use and generalized and abdominal obesity (categories shown in Table 1). Alcohol use was not included in multivariate analysis due to low prevalence. Body mass index (BMI) and waist circumference were used to determine generalized and abdominal obesity, using the WHO and International Diabetes Federation thresholds, respectively.25,26 We used two variables on residence: the region/LGA of participants and the rural/urban residence (determined using The Gambia Bureau of Statistics benchmarks).23 Table 1 Characteristics of study participants by selected demographic, behavioural and biological risk factors (unweighted and unadjusted for complex survey design) Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRRN, Central River Region North, CRRS, Central River Region South; URR, Upper River Region. a Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). The P-value indicates the difference between men and women. Table 1 Characteristics of study participants by selected demographic, behavioural and biological risk factors (unweighted and unadjusted for complex survey design) Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRRN, Central River Region North, CRRS, Central River Region South; URR, Upper River Region. a Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). The P-value indicates the difference between men and women. Data management and statistical analysis We report the prevalence of hypertension as percentages with their corresponding 95% confidence intervals (CI). We carried out age-adjusted bivariate analysis for each covariate separately, then used multivariate regression analysis to identify factors associated with hypertension. Each model was stratified by gender because of known marked differences in hypertension.14 The two hypertension outcomes described above were analysed separately. (Measured raised BP was also assessed: however, results were similar to total hypertension, and are therefore shown in Supplementary Tables, available as Supplementary data at IJE online). Due to the overlap of the two variables on residence, fully adjusted models were repeated interchanging these variables. Age-adjusted (aOR) and fully adjusted odds ratios (AOR) with corresponding 95% CI are reported. We explored variables that could modify the association between hypertension and potential sociodemographic and biological risk factors, by fitting interaction terms. There was no evidence of modification (all p > 0.05), and hence multivariate regression models without interaction terms are reported. Apart from the description of the characteristics of study participants, all analyses were weighted and adjusted for complex survey design, using Stata 14. Results Of the 4111 participants, 3573 had three valid BP measurements. Figure 1 outlines the number of participants excluded, with the reasons for exclusion. The unweighted sociodemographic, behavioural and biological risk factors are presented in Table 1. The mean age of participants was 38 ± 10.9 years. A high proportion (44%) were aged 25–34 years. Men were generally older, with a higher level of education than women (all P < 0.001). There was no age difference by gender after weighting (P = 0.953, Table S1). Most participants (98%) reported being lifetime abstainers from alcohol. The prevalences of generalized and abdominal obesity were higher among women (Table 1). Figure 1 View largeDownload slide Flow diagram of study participants with number excluded and reasons. Figure 1 View largeDownload slide Flow diagram of study participants with number excluded and reasons. Prevalence of hypertension The weighted mean systolic and diastolic BP were 130.3 mmHg (95% CI: 129.2–131.5) and 80.2 mmHg (95% CI: 79.5–81.0), respectively (Table S1). More than one-quarter (27%, 95% CI: 24.1–29.2) of participants had raised BP. When including self-reported hypertension, prevalence of total hypertension was 29% (95% CI: 26.6-31.8). Table 2 shows the prevalence of total and undiagnosed hypertension by gender. Hypertension was lower in Banjul and Kanifing, which are purely urban, and was higher in the more rural LGAs. This was also the case when rurality was used to denote residence. Prevalence was very high among the obese, those with a lower level of education and ex-smokers. More than three-quarters (79%, 95% CI: 74.5–82.2) of the participants classed as hypertensive were undiagnosed; this was higher among men (86%, 95% CI: 81.7–89.4 vs 71%, 95% CI: 65.2–76.9; P < 0.001). Undiagnosed hypertension was also higher among the younger age cohort and lower among the obese in both sexes (Table 2). Table 2 Prevalence of hypertension and proportion of total hypertension that is undiagnosed by selected sociodemographic and health factorsa,b Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River Region; N, unweighted sample/observations. a Total hypertension defined as measured SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension; undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Results adjusted for complex survey design and weighted for non-response. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). Table 2 Prevalence of hypertension and proportion of total hypertension that is undiagnosed by selected sociodemographic and health factorsa,b Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River Region; N, unweighted sample/observations. a Total hypertension defined as measured SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension; undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Results adjusted for complex survey design and weighted for non-response. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). Half (49%) of participants with reported hypertension (n = 314) were on treatment (data not shown). However, there was a major difference by LGA: the proportion was lower in rural regions. Only 24% of those on treatment had their BP controlled, with no gender difference (26% men vs 23% women, P = 0.787). Overall, only 14% of all hypertensives (according to the definition of total hypertension) were on treatment and only 4% had their BP controlled. Factors associated with hypertension Age, residence, generalized and abdominal obesity, smoking (men only), physical inactivity (women only) and ethnicity (women only) were strongly associated with total hypertension after mutually adjusting for these and other covariates (Table 3). As expected, the odds of hypertension increased with age. Compared with those from urban LGAs, participants from one of the most rural LGAs (Lower River Region) had higher odds of hypertension among both men (AOR 3.2, 95% CI: 1.6–6.4) and women (AOR 2.5, 95% CI: 1.3–4.6). Similarly, in models where rurality was used instead of LGA, participants from semi-urban and rural areas had higher odds of hypertension than urban residents (Table 3). Similar findings were found for the definition of hypertension based only on measured raised BP (Table S2). Table 3 Multivariate logistic regression on factors associated with total hypertension (SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. a OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted); KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River. * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^removed because of small numbers. Table 3 Multivariate logistic regression on factors associated with total hypertension (SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. a OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted); KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River. * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^removed because of small numbers. Among all those with hypertension, men (AOR 2.6, 95% CI: 1.6-4.3) and younger participants (AOR 8.0, 95% CI: 3.6-18.0) had higher adjusted odds of undiagnosed hypertension compared with women and older adults, respectively. Undiagnosed hypertension was also more common among the Jola participants, especially men, compared with other ethnic groups. However, it was less common among the obese (AOR 0.2, 95% CI: 0.1-0.4) and ex-smokers (AOR 0.4, 95% CI: 0.2-0.9) compared with those with normal weight and non-smokers, respectively. Similar findings were found after stratifying the analysis by gender (Table 4). We also conducted multinomial regression analysis on hypertension with three categories (normotensive, diagnosed and undiagnosed); the findings were similar (data not shown). Table 4 Multivariate logistic regression on factors associated with undiagnosed hypertension among participants with hypertension (total) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted). * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^not included in the model because of small numbers. a Undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Based on WHO standards. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥80 cm women). Table 4 Multivariate logistic regression on factors associated with undiagnosed hypertension among participants with hypertension (total) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted). * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^not included in the model because of small numbers. a Undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Based on WHO standards. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥80 cm women). Discussion This study has confirmed that the prevalence of hypertension is very high in The Gambia, and has revealed a greater burden in rural areas. Of great concern is the high proportion (79%) of the hypertensive cases that are undiagnosed. Rural residence was associated with hypertension after adjusting for other covariates. This association remained strong in all models, regardless of whether LGA or rurality was used. This is contrary to what has been found in most other studies in SSA. Urban residence was consistently associated with hypertension in similar STEP surveys conducted in Benin,27 Ethiopia,28 Ghana,29 Mozambique30 and Uganda.31 However, there was no difference between urban and rural residence in a similar study in Uganda.32 Undiagnosed hypertension did not vary by residence in The Gambia; the association with rural Gambia was for all hypertension, not an artefact of differential access to health care, diagnosis or treatment. This unique finding of higher odds of hypertension in rural areas in The Gambia could be associated with various factors. The more rural LGAs are the poorest: poverty levels range from 63% to 94%, compared with 8% in Banjul (the capital).33 Rural residents also have lower education levels.23 Even though people from higher wealth quintiles had higher risks of hypertension in previous studies,34,35 there is evidence on associations between low socioeconomic status and CVDs including hypertension.36,37 The lower risk of hypertension among rural dwellers observed in other countries in SSA may be related to occupational structure. Generally in SSA, rural dwellers are subsistence farmers, involved in laborious farming activities, whereas most jobs in urban areas are sedentary, leading to less opportunity for work-related physical activity.38 However in The Gambia, even though agriculture is the main economic activity in rural areas, it is becoming more mechanized. The farming season is also very short (May–October). Therefore, although farmers may be active on their farmlands during the farming season, they may be sedentary for the greater part of the year. The data were collected from January to March, a time when farmers are more likely to be sedentary. On the other hand, many adults in urban areas work in the construction, fishing and manufacturing industries, which are labour intensive39 but not seasonal. This is evident in the data, as 85% of participants met the WHO minimum recommendation on physical activity [≥ 600 metabolic equivalents (METS)/week], most of which is work- and transport-related. Another possible explanation could be diet, especially higher salt consumption. Peanuts are produced in The Gambia for export and local consumption. They can also be salted, roasted and used as snacks, which is very common in rural Gambia. High salt intake is a major risk factor for hypertension, especially among people of African descent.8,40–43 Other important associations with hypertension found in this study are overweight and obesity, being an ex-smoker, physical inactivity and ethnicity. The higher odds of hypertension among the overweight and obese are consistent with similar studies in SSA.29,32,34,44,45 There is growing evidence on the increasing burden of obesity in SSA; The Gambia is no exception. This could be related to the perception of many SSA communities that being overweight is associated with good life and high status, especially among women.46 Ex-smokers had higher odds of hypertension after adjusting for other covariates compared with never- and current-smokers. Smoking is a CVD risk factor, and it is likely that many ex-smokers had been advised to quit because they were hypertensive. Unlike other tribes, the Jolas have retained most of their traditional beliefs and practices,47 which could explain the lower odds of hypertension among the Jola women. Undiagnosed hypertension, treatment and control Almost four-fifths of hypertension in The Gambia is undiagnosed. This is consistent with findings from a national survey in Eritrea (80%),48 lower than in Mozambique (85%)30 and Malawi (95%),49 and higher than in The Republic of Seychelles (36%).50 Half (49%) of those in The Gambia with reported hypertension were on treatment, consistent with treatment levels in Mozambique30 but much lower than in The Republic of Seychelles (93%).50 Treatment, and the control of BP among those on treatment, were very low among rural residents in The Gambia. The major associations with undiagnosed hypertension among those with hypertension were age, gender, obesity, being an ex-smoker and ethnicity. The odds of being undiagnosed were highest among younger hypertensives. Younger adults are less likely to visit a clinic and have their BP monitored. Men also had higher odds of undiagnosed hypertension. Women have more contact with health services because of reproductive and child health care services, and hence are more likely to be diagnosed.51 The odds of undiagnosed hypertension were extremely high among the Jolas, especially among men. Jolas are the most traditional ethnic group47 and hence are less likely to visit orthodox medical clinics. Undiagnosed hypertension was lower among the obese and ex-smokers. There is evidence suggesting that being overweight/obese acts as a visual trigger for health care workers to check BP, and hence overweight/obese persons are more likely to be diagnosed.52,53 Strengths and limitations of this study This study provides the most recent nationally representative data on hypertension and its associated risk factors in The Gambia. A complex sampling strategy and the use of the Kish method to select only the eligible participants per household reduces biases introduced by sampling strategies that favour the selection of any available participant per household. The data were collected by health workers at the residence of the participants in a very relaxed environment, hence minimizing the effect of ‘white coat’ bias. There is evidence suggesting that the burden of undiagnosed hypertension is high in SSA but data on the correlates of undiagnosed hypertension are very limited. The study outlines the major associations with undiagnosed hypertension, which can be applied in policy making in The Gambia and other countries in SSA. The main limitation of this study is that BP was measured on only one occasion and therefore the prevalence of hypertension may be overestimated. However, this potential bias was minimized by using the mean of the second and third measurements. Salt intake, which is one of the indicators of the Global Action Plan for the prevention and control of NCDs,54 is a known risk factor for hypertension but was not part of the STEP instrument at the time of data collection. Some of the participants had missing BP measurements and hence were excluded (Table S3). The number excluded was very small but could have biased the estimates. Conclusions Contrary to what has been found in similar studies in SSA, where hypertension is highest in urban areas, we found that rural residence was strongly associated with hypertension in this study. Interventions to reduce the burden of hypertension could be further targeted towards rural areas. Overweight/obesity is one of the factors strongly associated with hypertension. There are socio-cultural norms that promote overweight in SSA. Sensitization campaigns should promote awareness of the risk factors, especially on the importance of maintaining a healthy weight. Preventive efforts should not only focus on physical activity and diet but also on socio-cultural factors that facilitate the increasing prevalence of overweight and consequent hypertension. Governments and donor agencies should increase their attention to NCDs, including capacity-building of health care providers and all relevant stakeholders. Doctors and nurses should be encouraged to check the BP of patients as a routine. With new technology of portable, battery-operated BP machines, there should be periodic and systematic screening for the early detection of hypertension. This unexpected finding in rural areas generates new hypotheses on diet and socio-cultural practices which should be explored. Supplementary Data Supplementary data are available at IJE online. Funding The survey was funded by the WHO, and Bai Cham’s PhD is funded by the Islamic Development Bank. Acknowledgements We thank the WHO for their technical and financial support to conduct this survey, and the Ministry of Health and Social Welfare of The Gambia for the authorization to use the data. We also thank Mr Momodou Gassama (WHO Country Office, The Gambia) and Mrs Musu Kuta Komma (staff of the Gambia Bureau of Statistics at the time of survey, and currently Country Director, ChildFund International, The Gambia Office), for their role in planning and execution of the survey. The first author thanks the Islamic Development Bank (IDB) for funding his PhD research at UCL (University College London). Conflict of interest: The authors have no conflict of interest to declare. References 1 Dalal S , Beunza JJ , Volmink J et al. Non-communicable diseases in sub-Saharan Africa: what we know now . Int J Epidemiol 2011 ; 40 : 885 – 901 . Google Scholar CrossRef Search ADS PubMed 2 Rosengren A , Subramanian SV , Islam S et al. 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Google Scholar CrossRef Search ADS PubMed 23 Gambia Bureau of Statistics . The Gambia 2013 Population and Housing Census Preliminary Results . Serre Kunda, The Gambia : Gambia Bureau of Statistics , 2013 . 24 WHO . STEPS:A Framework for Surveillance: The WHO STEPwise Approach to Surveillance of Non-communicable Diseases (STEPS) . Geneva : WHO , 2003 . 25 WHO . Obesity:Preventing and Managing the Global Epidemic. Report of a WHO Consultation . WHO Technical Report Series 894. Geneva : WHO , 2000 . 26 International Diabetes Federation . The IDF Consensus Worldwide Definition of the Metabolic Syndrome . Brussels : IDF , 2006 . PubMed PubMed 27 Houehanou YC , Lacroix P , Mizehoun GC , Preux PM , Marin B , Houinato DS. Magnitude of cardiovascular risk factors in rural and urban areas in Benin: findings from a nationwide STEPS survey . PLoS One 2015 ; 10 : e0126441 . Google Scholar CrossRef Search ADS PubMed 28 Tesfaye F , Nawi NG , Van Minh H et al. 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The epidemiology of hypertension in Uganda: Findings from the National Non-Communicable Diseases Risk Factor Survey . PLoS One 2015 ; 10 : e0138991 . Google Scholar CrossRef Search ADS PubMed 33 Gambia Bureau of Statistics . Poverty and Social Impact Analysis Report . Serre Kunda, The Gambia : 2009 . 34 Olack B , Wabwire-Mangen F , Smeeth L , Montgomery JM , Kiwanuka N , Breiman RF. Risk factors of hypertension among adults aged 35-64 years living in an urban slum Nairobi, Kenya . BMC Public Health 2015 ; 15 : 1251 . Google Scholar CrossRef Search ADS PubMed 35 Murphy GA , Asiki G , Ekoru K et al. Sociodemographic distribution of non-communicable disease risk factors in rural Uganda: a cross-sectional study . Int J Epidemiol 2013 ; 42 : 1740 – 53 . Google Scholar CrossRef Search ADS PubMed 36 Son M. The relationship of social class and health behaviors with morbidity in Korea . Korean J Prev Med 2002 ; 35 : 57 – 64 . 37 Kim S , Lee B , Park M , Oh S , Chin HJ , Koo H. 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Clin Exp Hypertens 1993 ; 15 : 781 – 96 . Google Scholar CrossRef Search ADS PubMed 43 De Wardener HE , MacGregor GA. Sodium and blood pressure . Curr Opin Cardiol 2002 ; 17 : 360 – 67 . Google Scholar CrossRef Search ADS PubMed 44 Pires JE , Sebastiao YV , Langa AJ , Nery SV. Hypertension in Northern Angola: prevalence, associated factors, awareness, treatment and control . BMC Public Health 2013 ; 13 : 90 . Google Scholar CrossRef Search ADS PubMed 45 Keetile M , Navaneetham K , Letamo G. Patterns and determinants of hypertension in Botswana . Z Gesundh Wiss 2015 ; 23 : 311 – 18 . Google Scholar CrossRef Search ADS PubMed 46 Scott A , Ejikeme CS , Clottey EN , Thomas JG. Obesity in sub-Saharan Africa: development of an ecological theoretical framework . Health Promot Int 2012 : das038 . 47 Colley E. 2007 . Gambian Culture Notes: Ethnic Groups and the Caste System. http://www.gambia.dk/culture_notes.pdf (18 April 2016, date last accessed). 48 Mufunda J , Mebrahtu G , Usman A et al. 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Published by Oxford University Press on behalf of the International Epidemiological Association This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Epidemiology Oxford University Press

Burden of hypertension in The Gambia: evidence from a national World Health Organization (WHO) STEP survey

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Oxford University Press
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© The Author(s) 2018; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association
ISSN
0300-5771
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1464-3685
D.O.I.
10.1093/ije/dyx279
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Abstract

Abstract Background Non-communicable diseases are increasing in sub-Saharan Africa and are estimated to account for 32% of adult deaths in The Gambia. Worldwide, prevalence of hypertension is highest in the African region (46%) and a very high proportion is undiagnosed. This study examined diagnosed and undiagnosed hypertension in The Gambian adult population. Methods Data were collected in 2010 from a nationally representative random sample of 4111 adults aged 25–64 years, using the World Health Organization STEPwise cross-sectional survey methods. Analyses were restricted to non-pregnant participants with three valid blood pressure measurements (n = 3573). We conducted gender-stratified univariate and multivariate regression analyses to identify the strongest sociodemographic, behavioural and biological risk factors associated with hypertension. Results Almost one-third of adults were hypertensive; a high proportion were undiagnosed, particularly among men (86% of men vs 71% of women with hypertension, P < 0.001). Rural and semi-urban residents and overweight/obese persons had increased odds of hypertension. Compared with urban residents, participants from one of the most rural regions had higher odds of hypertension among both men [adjusted odds ratio (AOR) 3.2; 95% CI: 1.6–6.4] and women (AOR 2.5; 95% CI: 1.3–4.6). Other factors strongly associated with hypertension in multivariate analyses were age, smoking, physical inactivity and ethnicity. Conclusions Rural and semi-urban residence were strongly associated with hypertension, contrary to what has been found in similar studies in sub-Saharan Africa. Intervention to reduce the burden of hypertension in The Gambia could be further targeted towards rural areas. Hypertension, Gambia, sub-Saharan Africa, WHO STEP survey, health examination survey Key Messages One-third of the adult population (25–64 years) in The Gambia are hypertensive and a high proportion of these are undiagnosed. Unlike previous studies in sub-Saharan Africa, hypertension was more prevalent in rural than urban residents in The Gambia. There should be periodic screening of blood pressure, especially among rural residents. Overweight and obesity were strongly associated with hypertension, and hence preventive efforts should be directed to diet and socio-cultural factors that facilitate the increasing burden of hypertension. Introduction Globally, there is an increasing epidemiological transition in the disease profile from infectious diseases and nutritional deficiencies to non-communicable diseases (NCDs), but the burden of NCDs is higher in sub-Saharan Africa (SSA).1–8 NCDs account for 70% of global deaths annually; 80% occur in low- and middle-income countries.9 Countries in SSA are also grappling with the double burden of communicable and non-communicable diseases.10,11 Less than 3% of global aid is directed towards NCD prevention and control.12 Hypertension is a global health challenge, with a higher burden in SSA. In 2008, the worldwide prevalence of hypertension among adults aged 25 years and above was 40% and was highest in Africa (46%).13 Of even greater concern, a large proportion of hypertension in Africa is undiagnosed.5,14 Although hypertension is the commonest modifiable risk factor for stroke and other cardiovascular diseases (CVDs) in Africa, its prevention and control are not prioritized.5,15 Early detection and treatment are crucial for the effective control of hypertension and the prevention of complications. NCDs are increasing in The Gambia, the smallest country on mainland Africa, with a population of 1.8 million. NCDs account for around 32% of adult deaths.16 A study using verbal autopsy in rural Gambia also found that 38% of deaths in 1998–2007 were associated with NCDs.17 Studies on hypertension in The Gambia are very limited; few used population-based health examination survey data. A population-based survey on hypertension (part of a nationwide survey on blindness and low vision in 1996) reported a prevalence of 10% (blood pressure ≥ 160/95 mmHg) among adults aged 15 years and above, and 24% above 140/90 mmHg.18 More than half of the participants in that study were surveyed during the holy month of Ramadan, which can influence the anthropometric and blood pressure (BP) measurements. A related study showed that people in The Gambia with a family history of hypertension had higher BP, cholesterol and uric acid than those without that family history.19 Hypertension poses both public health and economic burdens on individuals, families, governments and society.20 Many governments and families in SSA, including The Gambia, will not cope with this increasing burden coupled with the existing burden of infectious diseases. This can pose a barrier to poverty alleviation, hindering attainment of the United Nations Sustainable Development Goals.7,9,21,22 Despite this, there is very limited up-to-date information on the burden of hypertension and associated risk factors in The Gambia. This study aimed to examine diagnosed and undiagnosed hypertension in Gambian adults. Methods Study setting, design and sample This paper is based on secondary analysis of data from the WHO STEP survey conducted among adults aged 25–64 years from January to March 2010 in The Gambia.23 The survey is the most recent nationally representative, population-based, cross-sectional health examination survey in The Gambia, and the only one conducted based on the WHO STEPwise approach for NCDs. The WHO STEPwise approach, otherwise known as WHO STEPS, is a standard population-based health examination survey approach to NCD surveillance. Data are collected in up to three steps.24 Step one uses interview-based questionnaires, collecting information on sociodemographic and behavioural risk factors as well as history of diabetes and hypertension. Step two involves physical measurement of weight, height, waist circumference, blood pressure (BP) and pulse rate. (Biochemical measurement of fasting blood glucose and cholesterol is conducted in step three, not done in The Gambia.) Survey participants were selected using a multi-stage, stratified sampling technique based on the 2003 population census. The Gambia is divided into eight local government areas (LGAs) and 4098 enumeration areas (EAs). The LGAs served as sampling strata; 264 EAs were selected across the country by simple random sampling. The number of EAs selected per stratum (LGA) was proportional to the stratum population. From each selected EA, 20 households were selected by simple random sampling. One eligible participant was enrolled in each selected household, using the Kish method. The target was 5280, but 4111 responded (77.9% response rate). The age, sex and geographical distribution of the participants were similar to those of the 2003 and 2013 census reports; 232 pregnant women were excluded because of the impact of pregnancy on anthropometric and BP measurements. The analytical sample was limited to participants with three valid BP measurements (n = 3573). Research instrument and data collection Personal digital assistants (PDAs) programmed with eSTEPS software, an electronic version of the WHO STEPwise paper-based questionnaire, were used for data collection. eSTEPS has an automatic skip pattern and allows errors to be checked as the interview is ongoing, so is less prone to errors compared with the paper-based version. Data were collected by health staff drawn from all regions. Sampled participants were visited at their home for both interview and physical measurements. Eligible participants not reached after several visits, and those who declined to participate, were not replaced. BP was measured three times in the sitting position using an automated sphygmomanometer. Ethical approval was obtained from the national ethics committee; participants gave either verbal or written consent. Definition of variables Outcome variables Definitions of most of the variables were based on the WHO STEP criteria.24 The mean of the second and third BP readings was used in analysis. The main outcome variables in this study are: total hypertension, defined as measured raised BP (systolic BP ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg), and/or self-reported hypertension (as diagnosed by a doctor or health professional, which included all participants receiving treatment); undiagnosed hypertension, the proportion of participants with total hypertension not aware of their status before the survey. Covariates These comprised sociodemographic, behavioural and biological risk factors including age, ethnicity, education, residence, fruit and vegetable intake, physical inactivity, smoking, alcohol use and generalized and abdominal obesity (categories shown in Table 1). Alcohol use was not included in multivariate analysis due to low prevalence. Body mass index (BMI) and waist circumference were used to determine generalized and abdominal obesity, using the WHO and International Diabetes Federation thresholds, respectively.25,26 We used two variables on residence: the region/LGA of participants and the rural/urban residence (determined using The Gambia Bureau of Statistics benchmarks).23 Table 1 Characteristics of study participants by selected demographic, behavioural and biological risk factors (unweighted and unadjusted for complex survey design) Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRRN, Central River Region North, CRRS, Central River Region South; URR, Upper River Region. a Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). The P-value indicates the difference between men and women. Table 1 Characteristics of study participants by selected demographic, behavioural and biological risk factors (unweighted and unadjusted for complex survey design) Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 Variable Categories Men Women Total 1633 1940 3573 N % N % N % Age group 25–34 537 32.9 1030 53.1 1567 43.9 35–44 481 29.2 485 25.0 966 27.0 45–54 346 21.2 278 14.33 624 17.5 55–64 269 16.5 147 7.6 416 11.6 P < 0.001 Mean age (in years) 41.0 11.2 36.1 ± 10.1 38.3 ± 10.9 Ethnicity Mandinka 692 42.5 811 41.8 1503 42.1 Wollof 251 15.4 293 15.1 544 15.2 Fula 344 21.1 377 19.4 721 20.2 Jola 186 11.4 257 13.3 443 12.4 Other 157 9.6 201 10.4 358 10.0 P = 0.374 Years spent in school ≤ 6 years 938 62.3 1320 76.2 2258 69.7 7–12 years 376 25.0 353 20.4 729 22.5 > 12 years 191 12.7 60 3.5 251 7.8 P < 0.001 Residence (Local Government Area) Banjul 84 5.1 95 4.9 179 5.0 KMC 367 22.5 454 23.4 821 23.0 WCR 503 30.8 564 29.1 1067 30.0 LRR 138 8.5 157 8.1 295 8.3 NBR 254 15.6 356 18.4 610 17.1 CRRN 36 2.2 49 2.5 85 2.4 CRRS 83 5.1 108 5.6 191 5.4 URR 168 10.3 157 8.1 325 9.1 P = 0.139 Residence (Rurality) Urban 826 50.6 947 48.8 1773 49.6 Semi-urban 169 10.4 185 9.5 354 9.9 Rural 638 39.1 808 41.7 1446 40.5 P = 0.271 Physical activity < 600 METS/week 188 12.0 310 16.7 498 14.6 ≥ 600 METS/week 1377 88.0 1546 83.3 2923 85.4 P < 0.001 Smoking Never smokers 922 56.5 1906 98.3 2828 79.2 Current smokers 535 32.8 22 1.1 557 15.6 Ex-smokers 176 10.8 11 0.6 187 5.2 P < 0.001 Ever consumed alcohol Yes 61 3.7 22 1.1 83 2.3 No 1572 96.3 1917 98.9 3489 97.7 P < 0.001 Servings of fruits and vegetables < 5/day 1120 77.9 1336 77.6 2456 77.8 ≥ 5/day 318 22.1 385 22.4 703 22.2 P = 0.863 BMI (kg/m2) Underweight 162 10.1 160 8.4 322 9.2 Normal 911 56.9 937 49.3 1848 52.8 Overweight 403 25.2 517 27.2 920 26.3 Obese 124 7.8 286 15.1 410 11.7 P < 0. 001 Mean BMI 23.5 ± 4.5 24.9 ± 7.1 24.3 ± 6.1 Mean height (in cm) 167.2 ± 11.7 160.3 ± 9.8 163.5 ± 11.2 Mean weight (in kg) 65.2 ± 11.4 63.6 ± 17.0 64.3 ± 14.7 High waist circumferencea Normal 1402 87.8 993 53.2 2395 69.1 High 195 12.2 874 46.8 1069 30.9 P < 0.001 Mean waist circumference (cm) ± SD 72.9 ± 15.4 76.2 ± 17.7 74.7 ± 16.8 KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRRN, Central River Region North, CRRS, Central River Region South; URR, Upper River Region. a Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). The P-value indicates the difference between men and women. Data management and statistical analysis We report the prevalence of hypertension as percentages with their corresponding 95% confidence intervals (CI). We carried out age-adjusted bivariate analysis for each covariate separately, then used multivariate regression analysis to identify factors associated with hypertension. Each model was stratified by gender because of known marked differences in hypertension.14 The two hypertension outcomes described above were analysed separately. (Measured raised BP was also assessed: however, results were similar to total hypertension, and are therefore shown in Supplementary Tables, available as Supplementary data at IJE online). Due to the overlap of the two variables on residence, fully adjusted models were repeated interchanging these variables. Age-adjusted (aOR) and fully adjusted odds ratios (AOR) with corresponding 95% CI are reported. We explored variables that could modify the association between hypertension and potential sociodemographic and biological risk factors, by fitting interaction terms. There was no evidence of modification (all p > 0.05), and hence multivariate regression models without interaction terms are reported. Apart from the description of the characteristics of study participants, all analyses were weighted and adjusted for complex survey design, using Stata 14. Results Of the 4111 participants, 3573 had three valid BP measurements. Figure 1 outlines the number of participants excluded, with the reasons for exclusion. The unweighted sociodemographic, behavioural and biological risk factors are presented in Table 1. The mean age of participants was 38 ± 10.9 years. A high proportion (44%) were aged 25–34 years. Men were generally older, with a higher level of education than women (all P < 0.001). There was no age difference by gender after weighting (P = 0.953, Table S1). Most participants (98%) reported being lifetime abstainers from alcohol. The prevalences of generalized and abdominal obesity were higher among women (Table 1). Figure 1 View largeDownload slide Flow diagram of study participants with number excluded and reasons. Figure 1 View largeDownload slide Flow diagram of study participants with number excluded and reasons. Prevalence of hypertension The weighted mean systolic and diastolic BP were 130.3 mmHg (95% CI: 129.2–131.5) and 80.2 mmHg (95% CI: 79.5–81.0), respectively (Table S1). More than one-quarter (27%, 95% CI: 24.1–29.2) of participants had raised BP. When including self-reported hypertension, prevalence of total hypertension was 29% (95% CI: 26.6-31.8). Table 2 shows the prevalence of total and undiagnosed hypertension by gender. Hypertension was lower in Banjul and Kanifing, which are purely urban, and was higher in the more rural LGAs. This was also the case when rurality was used to denote residence. Prevalence was very high among the obese, those with a lower level of education and ex-smokers. More than three-quarters (79%, 95% CI: 74.5–82.2) of the participants classed as hypertensive were undiagnosed; this was higher among men (86%, 95% CI: 81.7–89.4 vs 71%, 95% CI: 65.2–76.9; P < 0.001). Undiagnosed hypertension was also higher among the younger age cohort and lower among the obese in both sexes (Table 2). Table 2 Prevalence of hypertension and proportion of total hypertension that is undiagnosed by selected sociodemographic and health factorsa,b Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River Region; N, unweighted sample/observations. a Total hypertension defined as measured SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension; undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Results adjusted for complex survey design and weighted for non-response. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). Table 2 Prevalence of hypertension and proportion of total hypertension that is undiagnosed by selected sociodemographic and health factorsa,b Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) Variable Categories Prevalence of total hypertension Proportion of total of hypertension that is undiagnosed Men Women Men Women n = 1633 n = 1940 n = 491 n = 509 N Hypertensive % (95% CI) χ2P-value N Hypertensive % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value N Undiagnosed % (95% CI) χ2P-value Total 1633 27.7 (24.5–31.2) 1940 30.5 (27.4–33.8) 491 86.0 (81.7–89.4) 509 71.4 (65.2–76.9) Age group 25–34 537 17.5 (13.9–21.8) < 0.001 1030 16.9 (44.9–61.7) < 0.001 101 95.3 (88.4–98.2) < 0.001 150 88.2 (80.4–93.2) < 0.001 35–44 481 26.3 (21.3–32.1) 485 33.6 (13.4–21.1) 109 93.7 (86.9–97.1) 153 73.0 (62.4–81.6) 45–54 346 43.0 (35.8–50.4) 278 45.4 (29.3–38.1) 135 85.7 (76.5–91.7) 115 65.9 (55.7–74.9) 55–64 269 53.4 (44.9–61.7) 147 60.4 (38.6–52.4) 146 61.3 (51.0–70.8) 91 54.7 (42.1–66.6) Ethnicity Mandinka 692 25.8 (21.4–30.9) 0.182 811 34.2 (30.0–38.7) 0.154 200 84.4 (78.3–89.0) 0.240 233 73.1 (64.6–80.2 0.464 Wollof 251 32.7 (25.7–40.6) 293 29.0 (22.6–36.3) 86 82.1 (67.8–90.9) 71 62.7 (45.9–76.9) Fula 344 26.4 (21.2–32.3) 377 29.4 (24.1–35.4) 101 85.3 (76.7–91.1) 95 67.5 (56.9–76.5) Jola 186 25.1 (18.1–33.6) 257 24.9 (19.6–31.1) 46 95.2 (87.6–98.2) 57 79.5 (61.8–90.3) Other 157 34.2 (26.7–42.6) 201 29.3 (21.4–38.6) 57 85.9 (78.9–96.0) 53 74.0 (54.7–87.1) Residence (Local Government Area) Banjul & KM 451 21.7 (15.6–29.5) 0.019 549 22.0 (17.3–27.6) < 0.001 97 87.6 (76.5–93.8) 0.759 106 75.0 (62.1–84.6) 0.514 WCR 503 28.5 (23.7–33.9) 564 33.7 (29.0–38.7) 151 88.0 (82.5–92.0) 146 71.0 (57.7–81.4) LRR 138 36.6 (30.0–43.8) 157 43.5 (32.5–55.1) 57 80.4 (71.0–87.2) 60 62.4 (46.6–75.9) NBR 254 34.8 (28.5–41.6) 356 38.8 (35.4–42.3) 99 81.0 (73.7–86.7) 121 74.0 (64.4–81.7) CRR 119 36.3 (28.7–44.7) 157 36.5 (28.8–45.0) 44 85.0 (58.0–95.9) 46 76.2 (62.3–86.2) URR 168 23.5 (15.0–44.7) 157 25.3 (18.7–33.4) 43 86.8 (65.1–95.9) 30 57.8 (35.8–77.1) Residence (Rurality) Urban 826 23.9 (19.6–28.8) 0.004 947 26.1 (22.2–30.4) 0.002 204 88.0 (81.8–92.3) 0.542 205 69.1 (59.4–77.3) 0.191 Semi-urban 169 29.5 (22.1–38.2) 185 42.1 (29.7–55.5) 51 81.9 (64.1–92.0) 59 62.2 (54.2–69.6) Rural 638 33.9 (29.6–38.6) 808 35.4 (31.7–39.3) 236 84.5 (77.5–89.6) 245 76.0 (66.0–83.8) Years spent in school ≤ 6 years 938 31.3 (27.7–35.0) 0.026 1320 35.5 (32.2–39.0) 0.002 319 81.3 (75.5–86.0) 0.024 391 70.1 (63.2–76.2) 0.522 7–12 years 376 24.7 (19.4–31.0) 353 20.9 (15.1–28.2) 99 94.7 (87.5–97.8) 56 62.5 (45.6–76.7) > 12 years 191 20.5 (13.7–29.6) 60 16.7 (8.6–29.9) 42 81.2 (59.6–92.7) 11 68.0 (36.9–88.5) Smoking Never smokers 922 25.1 (21.3–29.3) 0.001 264 88.3 (83.1–92.0) 0.004 Current smokers 535 26.7 (22.2–31.6) 152 89.7 (82.7–94.1) Ex-smokers 176 46.5 (34.7–58.6) 75 71.0 (55.0–83.1) Servings of fruits and veg < 5/day 1120 26.6 (22.7–30.8) 0.375 1336 31.6 (27.8–35.6) 0.529 339 85.4 (80.1–89.4) 0.358 358 70.6 (63.4–76.8) 0.091 ≥ 5/day 318 29.8 (23.8–36.6) 385 29.1 (23.2–35.8) 96 89.9 (80.8–95.0) 98 80.3 (69.8–87.8) BMI Underweight 162 25.3 (18.3–33.9) 0.831 160 22.5 (16.5–29.9) < 0.001 45 86.9 (73.7–94) < 0.001 30 76.9 (49.3–91.9) 0.023 Normal 911 27.4 (23.9–31.2) 937 26.3 (22.3–30.7) 273 91.1 (87.4–93.8) 213 79.3 (71.9–85.1) Overweight 403 29.8 (22.6–38.1) 517 32.8 (27.2–38.8) 132 80.6 (72.0–87.1) 157 69.1 (59.9–77.0) Obese 124 27.3 (18.2–38.8) 286 43.5 (35.1–52.3) 34 65.8 (46–81.2) 99 59.1 (45.3–71.5) High waist circumferencec Normal 1402 25.3 (21.9–29.0) < 0.001 993 23.7 (20.2–27.5) < 0.001 388 87.8 (83.3–91.2) 0.144 200 76.0 (66.3–83.6) 0.208 High 195 43.8 (36.0–52.0) 874 38.5 (32.1–43.0) 91 80 (67.5–88.5) 285 66.6 (58.0–74.3) KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River Region; N, unweighted sample/observations. a Total hypertension defined as measured SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension; undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Results adjusted for complex survey design and weighted for non-response. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥ 80 cm women). Half (49%) of participants with reported hypertension (n = 314) were on treatment (data not shown). However, there was a major difference by LGA: the proportion was lower in rural regions. Only 24% of those on treatment had their BP controlled, with no gender difference (26% men vs 23% women, P = 0.787). Overall, only 14% of all hypertensives (according to the definition of total hypertension) were on treatment and only 4% had their BP controlled. Factors associated with hypertension Age, residence, generalized and abdominal obesity, smoking (men only), physical inactivity (women only) and ethnicity (women only) were strongly associated with total hypertension after mutually adjusting for these and other covariates (Table 3). As expected, the odds of hypertension increased with age. Compared with those from urban LGAs, participants from one of the most rural LGAs (Lower River Region) had higher odds of hypertension among both men (AOR 3.2, 95% CI: 1.6–6.4) and women (AOR 2.5, 95% CI: 1.3–4.6). Similarly, in models where rurality was used instead of LGA, participants from semi-urban and rural areas had higher odds of hypertension than urban residents (Table 3). Similar findings were found for the definition of hypertension based only on measured raised BP (Table S2). Table 3 Multivariate logistic regression on factors associated with total hypertension (SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. a OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted); KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River. * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^removed because of small numbers. Table 3 Multivariate logistic regression on factors associated with total hypertension (SBP ≥ 140 mmHg and/or DBP ≥ 90 mmHg and/or self-reported hypertension) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 Reference Reference Reference Reference Reference Reference 35–44 1.68 (1.22–2.33)** 1.75 (1.15–2.67)** 1.54 (1.02–2.34)* 2.48 (1.78–3.45)*** 2.23 (1.53–3.28)*** 2.16 (1.47–3.16)*** 45–54 3.55 (2.40–5.25)*** 4.25 (2.68–6.78)*** 3.66 (2.32–5.76)*** 4.08 (2.78–5.99)*** 3.09 (1.97–4.84)*** 3.09 (1.99–4.82)*** 55–64 5.39 (3.34–8.70)*** 6.75 (3.78–12.03)*** 6.11 (3.48–10.73)*** 7.49 (4.26–13.20)*** 8.38 (4.88–14.39)*** 8.13 (4.62–14.33)** Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 1.27 (0.87–1.85) 1.22 (0.77–1.95) 1.10 (0.72–1.68) 0.71 (0.50–1.02) 0.84 (0.57–1.26) 0.79 (0.55–1.14) Fula 1.00 (0.69–1.45) 1.03 (0.64–1.66) 0.96 (0.61–1.52) 0.94 (0.68–1.30) 0.79 (0.51–1.22) 0.73 (0.48–1.14) Jola 0.90 (0.56–1.44) 0.85 (0.53–1.39) 0.86 (0.55–1.34) 0.62 (0.43–0.90)** 0.57 (0.38–0.86)** 0.59 (0.38–0.91)** Other 1.36 (0.93–1.97) 1.46 (0.90–2.37) 1.36 (0.85–2.19) 0.73 (0.47–1.13) 0.86 (0.48–1.55) 0.75 (0.42–1.33) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 1.94 (1.11–3.38)* 1.72 (0.99–3.02) 1.66 (0.96–2.88) 1.37 (0.59–3.16) 1.32 (0.53–3.27) 1.16 (0.49–2.76) ≤ 6 years 1.69 (0.99–2.89) 1.15 (0.66–2.00) 1.29 (0.76–2.20) 1.95 (0.92–4.11) 1.76 (0.74–4.20) 1.57 (0.67–3.67) Residence (LGA) Banjul and KM Reference Reference Reference Reference WCR 1.77 (1.09–2.87)* 2.58 (1.38–4.82)** 1.79 (1.19–2.70)** 2.36 (1.49–3.75)*** LRR 2.11 (1.31–3.42)** 3.17 (1.56–6.44)** 2.27 (1.32–3.89)** 2.46 (1.33–4.55)** NBR 1.88 (1.14–3.10)** 2.74 (1.33–5.67)** 2.00 (1.38–2.90)*** 2.19 (1.41–3.41)*** CRR 2.31 (1.33–4.03)** 2.74 (1.46–5.13)** 2.00 (1.34–2.98)*** 2.61 (1.66–4.11)*** URR 1.32 (0.64–2.72) 1.45 (0.55–3.85) 1.25 (0.74–2.11) 1.00 (0.50–2.04) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 1.37 (0.86–2.18) 1.75 (1.04–2.95)* 1.77 (1.09–2.89)* 1.76 (1.08–2.87)* Rural 1.54 (1.11–2.15)** 1.42 (0.99–2.04) 1.45 (1.08–1.94)** 1.61 (1.12–2.31)** Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 0.77 (0.50–1.19) 0.73 (0.37–1.45) 0.67 (0.35–1.30) 0.90 (0.57–1.42) 1.82 (1.21–2.73)** 1.68 (1.13–2.87)** Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.86–1.53) 1.12 (0.82–1.53) 1.21 (0.88–1.66) ^ – – Ex-smoker 2.21 (1.31–3.72)** 1.83 (1.00–3.33)* 2.02 (1.10–3.74)* – Servings of fruit & veg ≥ 5 day Reference Reference Reference Reference Reference Reference < 5 /day 0.81 (0.55–1.18) 0.75 (0.48–1.17) 0.79 (0.51–1.24) 1.10 (0.73–1.66) 1.05 (0.72–1.53) 1.05 (0.73–1.50) BMI Normal Reference Reference Reference Reference Reference Reference Underweight 0.95 (0.58–1.55) 0.99 (0.57–1.69) 1.08 (0.63–1.86) 0.72 (0.44–1.18) 0.52 (0.30–0.94)* 0.56 (0.31–1.01) Overweight 1.09 (0.75–1.58) 1.60 (1.10–2.32)* 1.17 (0.79–1.73) 1.23 (0.89–1.72) 1.44 (0.97–2.13) 1.26 (0.85–1.85) Obese 0.88 (0.50–1.53) 1.11 (0.52–2.35) 0.79 (0.37–1.70) 1.78 (1.15–2.76)** 2.54 (1.71–3.78)*** 2.22 (1.50–3.29)*** High waist circumference Normal Reference Reference Reference Reference Reference Reference High 1.89 (1.27–2.81)** 1.61 (1.01–2.54)* 2.00 (1.27–3.09)** 1.56 (1.16–2.11)** 1.19 (0.83–1.70) 1.47 (1.02–2.12)* Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. a OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted); KM, Kanifing Municipality; WCR, West Coast Region; LRR, Lower River Region; NBR, North Bank Region; CRR, Central River Region; URR, Upper River. * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^removed because of small numbers. Among all those with hypertension, men (AOR 2.6, 95% CI: 1.6-4.3) and younger participants (AOR 8.0, 95% CI: 3.6-18.0) had higher adjusted odds of undiagnosed hypertension compared with women and older adults, respectively. Undiagnosed hypertension was also more common among the Jola participants, especially men, compared with other ethnic groups. However, it was less common among the obese (AOR 0.2, 95% CI: 0.1-0.4) and ex-smokers (AOR 0.4, 95% CI: 0.2-0.9) compared with those with normal weight and non-smokers, respectively. Similar findings were found after stratifying the analysis by gender (Table 4). We also conducted multinomial regression analysis on hypertension with three categories (normotensive, diagnosed and undiagnosed); the findings were similar (data not shown). Table 4 Multivariate logistic regression on factors associated with undiagnosed hypertension among participants with hypertension (total) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted). * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^not included in the model because of small numbers. a Undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Based on WHO standards. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥80 cm women). Table 4 Multivariate logistic regression on factors associated with undiagnosed hypertension among participants with hypertension (total) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Variable Categories Men Women Model Ix Model IIy Model IIIz Model Ix Model IIy Model IIIz aOR (95% CI) AOR (95% CI) AOR (95% CI) aOR (95% CI) AOR (95% CI) AOR (95% CI) Age group 25–34 12.75 (4.37–37.2)*** 16.01 (5.56–46.07)** 15.38 (4.51–52.38)*** 6.23 (2.59–14.99)*** 4.97 (1.77–13.95)** 5.50 (1.83–16.52)*** 35–44 9.44 (4.41–20.19)*** 9.75 (3.75–25.38)*** 9.09 (3.57–23.16)*** 2.25 (1.19–4.26)* 2.10 (0.95–4.62) 2.22 (0.96–5.12) 45–54 3.78 (1.74–8.22)*** 6.71 (3.00–15.00)*** 6.71 (3.00–15.00)*** 1.61 (0.89–2.89) 1.43 (0.77–2.63) 1.52 (0.79–2.92) 55–64 Reference Reference Reference Reference Reference Reference Ethnicity Mandinka Reference Reference Reference Reference Reference Reference Wollof 0.89 (0.35–2.24) 2.09 (0.74–5.89) 2.74 (1.09–6.92)* 0.65 (0.28–1.54) 0.64 (0.27–1.54) 0.95 (0.41–2.19) Fula 1.24 (0.59–2.59) 0.97 (0.34–2.75) 1.07 (0.46–2.48) 0.63 (0.35–1.12) 0.62 (0.26–1.46) 0.77 (0.36–1.64) Jola 4.08 (1.30–12.76)* 6.85 (1.49–31.47) 5.44 (1.30–22.71)* 1.39 (0.56–3.44) 1.15 (0.45–2.94) 1.16 (0.49–2.74) Other 2.04 (0.65–6.43) 3.54 (0.78–16.14) 3.63 (0.77–17.23) 1.13 (0.41–3.09) 1.77 (0.56–5.55) 2.12 (0.75–6.00) Years in school > 12 years Reference Reference Reference Reference Reference Reference 7–12 years 2.37 (0.61–4.33) 1.45 (0.32–6.62) 1.49 (0.33–6.74) 0.70 (0.17–2.81) 1.11 (0.16–7.81) 1.17 (0.20–6.80) ≤ 6 Years 1.63 (0.68–8.29) 1.12 (0.37–3.40) 1.42 (0.48–4.22) 1.43 (0.50–4.11) 1.82 (0.42–7.83) 1.56 (0.39–6.29) Residence (LGA) Banjul & KM Reference Reference Reference Reference WCR 0.94 (0.36–2.42) 0.89 (0.35–2.30) 0.81 (0.36–1.86) 0.60 (0.20–1.78) LRR 0.93 (0.32–2.68) 1.37 (0.44–4.22) 0.69 (0.29–1.67) 0.45 (0.13–1.56) NBR 0.92 (0.35–2.38) 1.28 (0.39–4.25) 1.13 (0.53–2.41) 0.75 (0.24–2.35) CRR 1.13 (0.21–5.99) 3.30 (0.77–14.08) 1.18 (0.49–2.82) 1.67 (0.45–6.21) URR 0.85 (0.18–4.00) 0.77 (0.05–11.89) 0.42 (0.14–1.24) 4.45 (0.58–33.89) Residence (rurality) Urban Reference Reference Reference Reference Semi-urban 0.75 (0.24–2.32) 0.94 (0.30–2.92) 0.89 (0.49–1.60) 1.51 (0.82–2.78) Rural 1.10 (0.50–2.45) 1.01 (0.47–2.19) 1.56 (0.83–2.92) 1.69 (0.84–3.42) Physical activity ≥ 600 METS pw Reference Reference Reference Reference Reference Reference < 600 METS pw 1.93 (0.67–5.52) 1.50 (0.35–6.48) 1.72 (0.42–6.97) 0.83 (0.39–1.77) 0.57 (0.25–1.29) 0.77 (0.35–1.69) Smoking Non smoker Reference Reference Reference Reference Reference Reference Current smoker 1.15 (0.56–2.380 0.97 (0.39–2.43) 1.05 (0.44–2.55) ^ ^ ^ Ex-smoker 0.38 (0.18–0.88)* 0.51 (0.18–1.37) 0.56 (0.24–1.28) Servings of fruit and veg ≥ 5 /day Reference Reference Reference Reference Reference Reference < 5 /day 0.90 (0.34–2.37) 0.95 (0.32–2.85) 1.09 (0.38–3.09) 0.61 (0.32–1.19) 0.73 (0.25–2.08) 0.71 (0.28–1.75) BMIb Normal Reference Reference Reference Reference Reference Reference Underweight 0.57 (0.23–1.48) 0.77 (0.26–2.24) 0.75 (0.25–2.20) 0.96 (0.28–3.33) 1.95 (0.51–7.58) 1.66 (0.44–6.22) Overweight 0.35 (0.18–0.65)*** 0.41 (0.14–1.20) 0.40 (0.14–1.10) 0.59 (0.34–1.04) 0.51 (0.20–1.27) 0.53 (0.23–1.22) Obese 0.16 (0.06–0.46)*** 0.11 (0.02–0.53)** 0.10 (0.03–0.38)*** 0.40 (0.20–0.80)** 0.29 (0.12–0.69)** 0.35 (0.14–0.87)* High waist circumferencec Normal Reference Reference Reference Reference Reference Reference High 0.55 (0.24–1.28) 1.50 (0.34–6.48) 1.29 (0.37–4.51) 0.85 (0.46–1.56) 1.26 (0.62–2.61) 1.03 (0.52–2.03) Model Ix adjusted for age only, Model IIy adjusted for all variables except rurality, Model IIIz adjusted for all variables except local government area. OR, odds ratio adjusted for age (except for age group as the independent variable); AOR, adjusted odds ratio(fully adjusted). * P < 0.05, ** P ≤ 0.01, *** P ≤ 0.001, ^not included in the model because of small numbers. a Undiagnosed hypertension defined as proportion of hypertensives not aware of their condition prior to the survey. b Based on WHO standards. c Based on the definition of the International Diabetes Federation (≥ 90 cm men or ≥80 cm women). Discussion This study has confirmed that the prevalence of hypertension is very high in The Gambia, and has revealed a greater burden in rural areas. Of great concern is the high proportion (79%) of the hypertensive cases that are undiagnosed. Rural residence was associated with hypertension after adjusting for other covariates. This association remained strong in all models, regardless of whether LGA or rurality was used. This is contrary to what has been found in most other studies in SSA. Urban residence was consistently associated with hypertension in similar STEP surveys conducted in Benin,27 Ethiopia,28 Ghana,29 Mozambique30 and Uganda.31 However, there was no difference between urban and rural residence in a similar study in Uganda.32 Undiagnosed hypertension did not vary by residence in The Gambia; the association with rural Gambia was for all hypertension, not an artefact of differential access to health care, diagnosis or treatment. This unique finding of higher odds of hypertension in rural areas in The Gambia could be associated with various factors. The more rural LGAs are the poorest: poverty levels range from 63% to 94%, compared with 8% in Banjul (the capital).33 Rural residents also have lower education levels.23 Even though people from higher wealth quintiles had higher risks of hypertension in previous studies,34,35 there is evidence on associations between low socioeconomic status and CVDs including hypertension.36,37 The lower risk of hypertension among rural dwellers observed in other countries in SSA may be related to occupational structure. Generally in SSA, rural dwellers are subsistence farmers, involved in laborious farming activities, whereas most jobs in urban areas are sedentary, leading to less opportunity for work-related physical activity.38 However in The Gambia, even though agriculture is the main economic activity in rural areas, it is becoming more mechanized. The farming season is also very short (May–October). Therefore, although farmers may be active on their farmlands during the farming season, they may be sedentary for the greater part of the year. The data were collected from January to March, a time when farmers are more likely to be sedentary. On the other hand, many adults in urban areas work in the construction, fishing and manufacturing industries, which are labour intensive39 but not seasonal. This is evident in the data, as 85% of participants met the WHO minimum recommendation on physical activity [≥ 600 metabolic equivalents (METS)/week], most of which is work- and transport-related. Another possible explanation could be diet, especially higher salt consumption. Peanuts are produced in The Gambia for export and local consumption. They can also be salted, roasted and used as snacks, which is very common in rural Gambia. High salt intake is a major risk factor for hypertension, especially among people of African descent.8,40–43 Other important associations with hypertension found in this study are overweight and obesity, being an ex-smoker, physical inactivity and ethnicity. The higher odds of hypertension among the overweight and obese are consistent with similar studies in SSA.29,32,34,44,45 There is growing evidence on the increasing burden of obesity in SSA; The Gambia is no exception. This could be related to the perception of many SSA communities that being overweight is associated with good life and high status, especially among women.46 Ex-smokers had higher odds of hypertension after adjusting for other covariates compared with never- and current-smokers. Smoking is a CVD risk factor, and it is likely that many ex-smokers had been advised to quit because they were hypertensive. Unlike other tribes, the Jolas have retained most of their traditional beliefs and practices,47 which could explain the lower odds of hypertension among the Jola women. Undiagnosed hypertension, treatment and control Almost four-fifths of hypertension in The Gambia is undiagnosed. This is consistent with findings from a national survey in Eritrea (80%),48 lower than in Mozambique (85%)30 and Malawi (95%),49 and higher than in The Republic of Seychelles (36%).50 Half (49%) of those in The Gambia with reported hypertension were on treatment, consistent with treatment levels in Mozambique30 but much lower than in The Republic of Seychelles (93%).50 Treatment, and the control of BP among those on treatment, were very low among rural residents in The Gambia. The major associations with undiagnosed hypertension among those with hypertension were age, gender, obesity, being an ex-smoker and ethnicity. The odds of being undiagnosed were highest among younger hypertensives. Younger adults are less likely to visit a clinic and have their BP monitored. Men also had higher odds of undiagnosed hypertension. Women have more contact with health services because of reproductive and child health care services, and hence are more likely to be diagnosed.51 The odds of undiagnosed hypertension were extremely high among the Jolas, especially among men. Jolas are the most traditional ethnic group47 and hence are less likely to visit orthodox medical clinics. Undiagnosed hypertension was lower among the obese and ex-smokers. There is evidence suggesting that being overweight/obese acts as a visual trigger for health care workers to check BP, and hence overweight/obese persons are more likely to be diagnosed.52,53 Strengths and limitations of this study This study provides the most recent nationally representative data on hypertension and its associated risk factors in The Gambia. A complex sampling strategy and the use of the Kish method to select only the eligible participants per household reduces biases introduced by sampling strategies that favour the selection of any available participant per household. The data were collected by health workers at the residence of the participants in a very relaxed environment, hence minimizing the effect of ‘white coat’ bias. There is evidence suggesting that the burden of undiagnosed hypertension is high in SSA but data on the correlates of undiagnosed hypertension are very limited. The study outlines the major associations with undiagnosed hypertension, which can be applied in policy making in The Gambia and other countries in SSA. The main limitation of this study is that BP was measured on only one occasion and therefore the prevalence of hypertension may be overestimated. However, this potential bias was minimized by using the mean of the second and third measurements. Salt intake, which is one of the indicators of the Global Action Plan for the prevention and control of NCDs,54 is a known risk factor for hypertension but was not part of the STEP instrument at the time of data collection. Some of the participants had missing BP measurements and hence were excluded (Table S3). The number excluded was very small but could have biased the estimates. Conclusions Contrary to what has been found in similar studies in SSA, where hypertension is highest in urban areas, we found that rural residence was strongly associated with hypertension in this study. Interventions to reduce the burden of hypertension could be further targeted towards rural areas. Overweight/obesity is one of the factors strongly associated with hypertension. There are socio-cultural norms that promote overweight in SSA. Sensitization campaigns should promote awareness of the risk factors, especially on the importance of maintaining a healthy weight. Preventive efforts should not only focus on physical activity and diet but also on socio-cultural factors that facilitate the increasing prevalence of overweight and consequent hypertension. Governments and donor agencies should increase their attention to NCDs, including capacity-building of health care providers and all relevant stakeholders. Doctors and nurses should be encouraged to check the BP of patients as a routine. With new technology of portable, battery-operated BP machines, there should be periodic and systematic screening for the early detection of hypertension. This unexpected finding in rural areas generates new hypotheses on diet and socio-cultural practices which should be explored. Supplementary Data Supplementary data are available at IJE online. Funding The survey was funded by the WHO, and Bai Cham’s PhD is funded by the Islamic Development Bank. Acknowledgements We thank the WHO for their technical and financial support to conduct this survey, and the Ministry of Health and Social Welfare of The Gambia for the authorization to use the data. We also thank Mr Momodou Gassama (WHO Country Office, The Gambia) and Mrs Musu Kuta Komma (staff of the Gambia Bureau of Statistics at the time of survey, and currently Country Director, ChildFund International, The Gambia Office), for their role in planning and execution of the survey. The first author thanks the Islamic Development Bank (IDB) for funding his PhD research at UCL (University College London). Conflict of interest: The authors have no conflict of interest to declare. References 1 Dalal S , Beunza JJ , Volmink J et al. Non-communicable diseases in sub-Saharan Africa: what we know now . Int J Epidemiol 2011 ; 40 : 885 – 901 . Google Scholar CrossRef Search ADS PubMed 2 Rosengren A , Subramanian SV , Islam S et al. 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International Journal of EpidemiologyOxford University Press

Published: Jan 30, 2018

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