Cohort Profile: The China Hainan Centenarian Cohort Study (CHCCS)

Cohort Profile: The China Hainan Centenarian Cohort Study (CHCCS) Why was the cohort set up? The proportion of the world population aged 60 years or over is expected to increase from 12% in 2013 to 21% in 2050. This increase will represent more than 2 billion elderly individuals, including 400 million people aged 80 years or older and 3.4 million centenarians in 2050.1 The population of individuals of advanced ages, including near-centenarians and centenarians, has become the fastest-growing segment of the population.2 This growth has led to considerable concern about the social and economic burden of disease and disability in this age group, for the oldest old are vulnerable to multiple age-related chronic conditions and disabilities and are at a high risk of losing their independence.3 Previous studies have indicated that exceptional longevity does not result in excessive levels of disability.4,5 In fact, some centenarians experience a delayed onset of age-related illnesses (delayers), whereas others do not succumb to any age-related illnesses (escapers).6 In addition, one case-control study showed that older individuals had a delayed age of onset of cancer, cardiovascular disease, diabetes mellitus, hypertension and osteoporosis than their respective younger reference groups.7 Thus, centenarians may represent a prototype of successful ageing.8 However, a Danish centenarian study identified only one physically healthy centenarian in a sample of over 200 participants9 and indicated that whether centenarians represent a model of successful ageing is still under scientific debate.10 Thus, studies on groups of centenarians can provide valuable information for the early prevention of major diseases, premature ageing and early death, thus providing the scientific support necessary to cope with the quickly approaching arrival of an ageing society in China. Longevity research has shown that no single factor contributes to reaching an exceptionally high age or to differences in survival. Previous research on centenarians has primarily examined biological indicators or medical aspects,11–15 and relatively little sociological, psychological or functional research has been undertaken with centenarians. However, data are currently available from Australian,16 Japanese,17 Hungarian, Greek,18 Swedish,19 American,10,20,21 German22 and Chinese23 studies. However, most of these studies provide evidence from developed countries. In contrast, very old individuals, including centenarians, in developing countries remain an under-studied and under-served population. In addition, only a few studies extensively examine data from medical, psychological and sociological domains simultaneously. Furthermore, the uncertain representativeness of centenarians and the lack of participant age verification in some studies make it difficult to draw reliable conclusions about this population.24 Therefore, we organized an interdisciplinary research team consisting of geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, nurses, a psychologist, a sociologist and epidemiologists to conduct a longitudinal observational study that targeted the population aged 100 years or older in Hainan, China. Hainan province has one of the highest life expectancies in China (76.3 years in 2010) and was authorized by the International Expert Committee on Population Aging and Longevity as ‘World Longevity Island’ on 27 August 2014 for its highest percentage of centenarians (18.75/100 000) in China.25 Most centenarians are indigenous and have lived on this island for their entire lives; thus, this population provided a steady gene pool for longevity-related genetic research. Based on this prospective community-based study, the China Hainan Centenarian Cohort Study (CHCCS) was established with three main objectives. The first objective is to evaluate the centenarians’ physical and mental health status as well as their social conditions, which are especially important in a developing country such as China, where broad economic constraints lead to numerous hardships. The second goal is to propose strategies to solve problems identified during this study. For example, participants with previously undetected health problems are referred to appropriate local health care providers after we have interviewed them and identified their needs. The third goal is to establish healthy ageing indicators that could be used to plan and conduct population-wide health interventions in the future. Who are the participants in the cohort? The CHCCS was designed as a complete sample study. The base study population of the CHCCS comprised male and female individuals aged 100 years or older throughout the Hainan provincial area (Figure 1). In total there were 1811 living centenarians, according to the household register provided by the civil affairs bureau in 2014. According to contact addresses from June 2014 to December 2016, 1473 living centenarians in 18 cities and counties of Hainan province were involved in CHCCS. The following inclusion criteria were used to recruit study participants: (i) was 100 years or older by 1 June 2014; (ii) volunteered to participate in the study and provided written informed consent; and (ii) was conscious and could cooperate to complete the questionnaire interview, physical health examination and blood tests. The following were participant exclusion criteria: (i) personal identity information was not complete or ID card showed an age of less than 100 years; (ii) refused to comply with the requirements of the study, including the collection of physical or biological samples. Table 1 shows the distribution of centenarians in Hainan province and the centenarians involved in the CHCCS. Table 1 The distribution of centenarians in Hainan and the sample size in CHCCS Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Table 1 The distribution of centenarians in Hainan and the sample size in CHCCS Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Figure 1 View largeDownload slide Location of Hainan province, with 1811 living centenarians in 2014. Figure 1 View largeDownload slide Location of Hainan province, with 1811 living centenarians in 2014. To ensure the quality of the data and to prevent participants from overstating their ages, an age verification process was conducted before the participants were included in the study. Figure 2 shows the age validation process. It was an unprecedented challenge to recruit an entire sample of centenarians for an epidemiological study that included a detailed questionnaire and an extended clinical examination. Therefore, support from the Department of Civil Affairs of Hainan Province was critical, since this department has the household register of the indigenous elderly population and is responsible for providing monthly subsidies for individuals over 80 years of age. With their help, we were able to obtain a detailed list of centenarians throughout Hainan, containing their demographic and residential information. In addition, the Department of Civil Affairs of Hainan Province announced that each subordinate unit of the municipal and prefectural level would offer additional assistance, such as connecting with the indigenous centenarians and convening them for our study. Figure 2 View largeDownload slide Age validation process of centenarians in CHCCS. Figure 2 View largeDownload slide Age validation process of centenarians in CHCCS. To capture a wide range of health indicators within this age group and to allow them to conveniently participate in this programme, the eligible individuals were given the choice of completing the interview and examination either at home or in the community health service centres (public clinics). The home-based option was mainly for participants who were unable to transport themselves to the clinic or who lived far from the clinics. The clinic-based option required mobility of the participants. Several participants gathered in clinics nearby; thus, the multi-specialty medical group could conduct the survey and examination with a larger group of centenarians, which allowed for greater efficiency and organization of data collection. The pilot study was initiated in January 2014, and baseline interviews and examinations were subsequently conducted. This process was separated into two phases: Phase 1 and Phase 2, conducted from July 2014 to November 2015 and from March 2016 to December 2016, respectively. Baseline surveys were suspended during the winter because the participants were potentially vulnerable to the Hainan climate. Figures 3 and 4 show the participant recruitment and study scheme. The researchers obtained ethics approval from the Ethics Committee of the Chinese People’s Liberation Army General Hospital (Beijing, China). Each participant provided written informed consent to be included in the study. Figure 3 View largeDownload slide Participant recruitment in CHCCS. Figure 3 View largeDownload slide Participant recruitment in CHCCS. Figure 4 View largeDownload slide Study scheme in CHCCS. Figure 4 View largeDownload slide Study scheme in CHCCS. What was measured? The CHCCS baseline assessment consisted of a self-administered questionnaire with face-to-face interview, interdisciplinary examinations and a laboratory analysis. To permit valid comparisons with other studies, including the CKB,26 CLHLS,27 CHARLS28 and national and international epidemiological studies of centenarian populations, the CHCCS deliberately used standardized and validated instruments for data collection (Table 2). These instruments were pre-tested on a convenience sample of 48 centenarians who resided in Sanya suburb, and the instruments were slightly simplified before the procedure began. For the interview and examination, participants were visited at their residences or nearby clinics by a well-trained interdisciplinary medical group. The interview was performed by native nurses who were trained in interviewing older persons and spoke the local dialect. The interview session required approximately 45 min to complete, depending on each subject’s status, including visual and hearing acuity and cognitive function. Table 2 Contents of the baseline data collection in CHCCS Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Table 2 Contents of the baseline data collection in CHCCS Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Data collection on participants in the CHCCS (Table 3) began with a brief introduction and informed consent for both the procedure and DNA banking. After participants signed the consent form, 8 ml of fasting blood was drawn from participants by experienced nurses using four vacutainer tubes (2 ml each), two of which were purple-top anticoagulant tubes containing ethylenediaminetetraacetic acid (EDTA) and two of which were yellow-top serum-separating tubes (SST). After obtaining a fasting blood sample, subjects were given a free breakfast and then prepared to complete the interview and the rest of the physical examination. Using a face-to-face interview in the appropriate regional dialect, the interviewers recorded detailed information on the standardized structured questionnaire, including sociodemographics, personal and family disease histories, functional status, cognitive and mental health status, lifestyles, diet, sleep quality, leisure and physical activities, economic status, social support, health service use and reproductive histories (for females only). Then clinical examinations were conducted by the study group, including the measurement of blood pressure, anthropometric indices, geriatric syndromes and visual and hearing acuity as well as the administration of 12-lead electrocardiography, ultrasonography, an equipped dental examination and a gynaecological examination. The study group consisted of experienced geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, and trained nurses with average of 5 years of practice from the Hainan Branch of the Chinese PLA General Hospital. Biological specimens, including hair and saliva, were obtained and delivered to the hospital alongside blood and faeces samples, which were stored separately in refrigerated containers on the same day. Table 3 Summary of clinical measurements collected at baseline in CHCCS Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      a Evaluation of oral hygiene included dental plaque, odontolith, saprodontia and gums bleeding on probing. b White (leukocytes) and red blood cell (erythrocytes) counts, and platelets (thrombocytes). c Electrolytes, serum glucose, blood urea nitrogen, creatinine, serum calcium, serum total protein (TP), serum albumin, bilirubin, alkaline phosphatase (ALP), aspartate amino transferase (AST) and alanine amino transferase (ALT or SGPT). d Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. e Anti-cardiolipin antibody (ACL), complement component 4 (C4), immunoglobulin A (IgA), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM). f Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), cancer antigen 125 (CA 125), cancer antigen 19-9 (CA 19-9), cancer antigen 15-3 (CA 15-3), cancer antigen 724 (CA 724). g Estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), progesterone (PROG), testosterone (TES). Table 3 Summary of clinical measurements collected at baseline in CHCCS Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      a Evaluation of oral hygiene included dental plaque, odontolith, saprodontia and gums bleeding on probing. b White (leukocytes) and red blood cell (erythrocytes) counts, and platelets (thrombocytes). c Electrolytes, serum glucose, blood urea nitrogen, creatinine, serum calcium, serum total protein (TP), serum albumin, bilirubin, alkaline phosphatase (ALP), aspartate amino transferase (AST) and alanine amino transferase (ALT or SGPT). d Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. e Anti-cardiolipin antibody (ACL), complement component 4 (C4), immunoglobulin A (IgA), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM). f Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), cancer antigen 125 (CA 125), cancer antigen 19-9 (CA 19-9), cancer antigen 15-3 (CA 15-3), cancer antigen 724 (CA 724). g Estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), progesterone (PROG), testosterone (TES). How often has participant follow-up been conducted? Every centenarian was followed up through an annual telephone interview and electronic health records check. The annual follow-up purported to examine outcomes such as living conditions, new diseases, institutionalization, morbidity, sustainability of health behaviours and social participation, disability in instrumental and basic activities of daily living (ADLs), family support, main cause of death and migration. Telephone interviews were conducted by the study staff, and medical information was obtained from the centenarians, their relatives and village doctors. Electronic health records from the health care system and the household registration system of the public security were reviewed to confirm the cause of death or migration. The two follow-up approaches were used to confirm and complement each other, to ensure that the information was credible and comprehensive. What results have been found in the CHCCS? The number of province-registered centenarians was 1811 in February 2014. In June 2014, when the CHCCS began, the number of living centenarians available by register address was 1473. By December 2016, 268 centenarians had died, 203 refused to participate and 1002 agreed to participate in this study, and the response rate was 86.2% (Table 1). Centenarians who did and did not respond showed similar distribution in age and gender (P = 0.27 and 0.56 respectively, Table 4). Table 4 Participants and nonparticipantsa according to age and sex in CHCC Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    a Non-participants included those who had died, moved or declined the survey. b The chi-square test was used to examine the gender differences between dead and alive participants. c The chi-square test was used to examine the gender differences between non-participants and participants. d The t-test was used to examine age differences between non-participants and participants. Table 4 Participants and nonparticipantsa according to age and sex in CHCC Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    a Non-participants included those who had died, moved or declined the survey. b The chi-square test was used to examine the gender differences between dead and alive participants. c The chi-square test was used to examine the gender differences between non-participants and participants. d The t-test was used to examine age differences between non-participants and participants. Excluding centenarians with more than 25% missing data, the baseline sociodemographic characteristics of 990 CHCCS participants are shown in Table 5. The range of ages was 100-115 years among the centenarians, and their average age was 102.85±2.76 years (102.45±2.31 years for men and 102.94±2.84 years for women). A total of 81.9% (n = 811) of participants were women. Compared with men, women tend to be widowed (92.8%), be illiterate (96.5%), live together with families (87.5%) and have a body mass index (BMI) < 24.0 (96.7%). Table 5 Sociodemographic variables of the CHCCS participants in CHCCS Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Table 5 Sociodemographic variables of the CHCCS participants in CHCCS Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Selected geriatric syndromes and self-reported chronic conditions among CHCCS participants are shown in Table 6. Geriatric syndromes and chronic conditions are two of our main areas of focus. A total of 27.5%, 30.7% and 22.0% centenarians reported vision impairment, hearing impairment, and dizziness, respectively. In addition, 6.9% fell more than three times in the previous month. Compared with men, women tended to report their health as bad (24.3% vs 16.7%) and more likely to be dependent (74.8% vs 58.7%, P < 0.05). The most common self-reported chronic condition was hypertension (23.2%). Table 6 Selected geriatric syndromes and self-reported chronic conditions in CHCCS participants   All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)      All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)    Table 6 Selected geriatric syndromes and self-reported chronic conditions in CHCCS participants   All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)      All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)    What are the main strengths and weakness of the CHCCS? Hainan province has the highest density of centenarians and the highest longevity index in China. Furthermore, it has an independent sea island area that is relatively closed and has a low proportion of immigrants. Therefore, there is a high homogeneity of centenarians, which made it relatively easy to achieve the goals of our study. Second, the CHCCS is supported by the government of Hainan province; thus, sampling, household surveys and an electronic medical records check can be guaranteed, minimizing the loss of participants at follow-up. Third, the interdisciplinary research team of the CHCCS is composed of geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, nurses and epidemiologists. This team evaluated the centenarians’ health situation and studied the mechanisms of longevity. Further, by relying on the Chinese PLA General Hospital (the largest hospital in Hainan province), we collected various biomarkers covering almost every organ and system of the body. Furthermore, the blood samples were numbered and reserved using the standard system, which is conducive to future studies of this population. The high age of participants in the CHCCS suggests that a sufficient number of incident outcome events can be expected within a relatively short time period. The results from the CHCCS and its subgroup of relevant nested case-control studies can be expected within a short time frame. However, several limitations must be mentioned. Our subjects are unlikely to be completely representative of the centenarians of China, so the generalizability of the results is limited. Second, we cannot rule out the possibility of healthy volunteer bias among centenarians who chose to participate in the study. Third, we cannot exclude the possibility of recall bias during the data collection process, although we asked the same questions of participants and their relatives for reliability checking. Fourth, even with the support of the Hainan government, we cannot rule out the possibility of withdrawal bias in the annual follow-up of this large sample of centenarians. Can I obtain the data? Where can I learn more? Although there is no immediate plan to make the data freely available in the public domain, specific proposals for further collaboration are welcome. For further information, please contact the corresponding authors via e-mail: [yhe301@x263.net] or [baisui301@163.com]. The China Hainan Centenarian Cohort Study (CHCCS) profile in a nutshell CHCCS is a cohort of a complete sample for individuals aged 100 years or older throughout the China Hainan provincial area. CHCCS has three goals. The first goal is to evaluate the centenarians’ physical and mental health status as well as their social conditions, which are especially important in a developing country such as China, where broad economic constraints lead to numerous hardships. The second goal is to propose strategies to solve problems identified during this study. For example, participants with previously undetected health problems are referred to appropriate local health care providers after we have interviewed them and identified their needs. The third goal is to establish healthy ageing indicators that could be used to plan and conduct population-wide health interventions in the future. A total of 1002 centenarians were recruited at baseline, 2014-16, from China, Hainan provincial area. The dataset comprises a wide range of variables (911 from questionnaire; 719 from interdisciplinary examinations and a laboratory analysis). These include: demographic characteristics; anthropometric measures; socioeconomic status; lifetime lifestyle; present medical history; family medical history; health outcomes; biological samples including blood and DNA; and cognitive function measures etc. Specific proposals for collaboration are welcomed. Further information can be found via e-mail to [yhe301@x263.net] or [baisui301@163.com]. Acknowledgements We thank the Department of Civil Affairs of Hainan Province for connecting with and convening the centenarians. The CHCCS investigators include the following: the Hainan Branch of Chinese PLA General Hospital: J Li, XP Chen, Q Zhu, F Zhang, Y L Zhao (Co-PI) and F X Luan (Co-PI); the Institute of Geriatrics, Chinese PLA General Hospital: SS Yang, Y Yao, J Li, M Liu, J H Wang, X Y Li and Y He (Co-PI). Funding The study is funded by: Key Research and Development Program of Hainan of the Hainan Science and Technology Bureau in China (ZDYF2016135, ZDYF2017095); State Key Development Program of Basic Research of China(973 program) (2013CB530800); National Key Research and Development Program in China(2016YFC1303603) and the National Natural Science Foundation of China (81773502 and 81703308). Conflict of interest: None declared. References 1 United Nations. World Population Ageing 2013 . New York, NY: Population Division of Department of Economic and Social Affairs New York, 2013. 2 US Department of Health and Human Services. Why Population Aging Matters. A Global Perspective . 2007. https://www.nia.nih.gov/research/publication/why-population-aging-matters-global-perspective (16 June 2015, date last accessed). 3 Arai Y, Iinuma T, Takayama M et al.   The Tokyo Oldest Old survey on Total Health (TOOTH): a longitudinal cohort study of multidimensional components of health and well-being. BMC Geriatr  2010; 10: 35. Google Scholar CrossRef Search ADS PubMed  4 Christensen K, McGue M, Petersen I, Jeune B, Vaupel JW. Exceptional longevity does not result in excessive levels of disability. Proc Natl Acad Sci U S A  2008; 105: 13274– 79. Google Scholar CrossRef Search ADS PubMed  5 Hitt R, Young-Xu Y, Silver M, Perls T. Centenarians: the older you get, the healthier you have been. Lancet  1999; 354: 652. Google Scholar CrossRef Search ADS PubMed  6 Evert J, Lawler E, Bogan H, Perls T. Morbidity profiles of centenarians: survivors, delayers, and escapers. J Gerontol A Biol Sci Med Sci  2003; 58: 232– 37. Google Scholar CrossRef Search ADS PubMed  7 Ismail K, Nussbaum L, Sebastiani P et al.   Compression of morbidity is observed across cohorts with exceptional longevity. J Am Geriatr Soc  2016; 64: 1583– 91. Google Scholar CrossRef Search ADS PubMed  8 Motta M, Bennati E, Ferlito L, Malaguarnera M, Motta L; Italian Multicenter Study on Centenarians. Successful aging in centenarians: myths and reality. Arch Gerontol Geriatr  2005; 40: 241– 51. Google Scholar CrossRef Search ADS PubMed  9 Andersen-Ranberg K, Schroll M, Jeune B. Healthy centenarians do not exist, but autonomous centenarians do: a population-based study of morbidity among Danish centenarians. J Am Geriatr Soc  2001; 49: 900– 08. Google Scholar CrossRef Search ADS PubMed  10 Jopp DS, Park MK, Lehrfeld J, Paggi ME. Physical, cognitive, social and mental health in near-centenarians and centenarians living in New York City: findings from the Fordham Centenarian Study. BMC Geriatr  2016; 16: 1. Google Scholar CrossRef Search ADS PubMed  11 Atzmon G, Cho M, Cawthon RM et al.   Evolution in health and medicine Sackler colloquium: Genetic variation in human telomerase is associated with telomere length in Ashkenazi centenarians. Proc Natl Acad Sci USA  2010; 107(Suppl 1): 1710– 17. Google Scholar CrossRef Search ADS PubMed  12 Ferrario A, Villa F, Malovini A, Araniti F, Puca AA. The application of genetics approaches to the study of exceptional longevity in humans: potential and limitations. Immun Ageing  2012; 9: 7. Google Scholar CrossRef Search ADS PubMed  13 van der Spoel E, Rozing MP, Houwing-Duistermaat JJ et al.   Association analysis of insulin-like growth factor-1 axis parameters with survival and functional status in nonagenarians of the Leiden Longevity Study. Aging (Albany NY)  2015; 7: 956– 63. Google Scholar CrossRef Search ADS PubMed  14 Willcox DC, Willcox BJ, Hsueh WC, Suzuki M. Genetic determinants of exceptional human longevity: insights from the Okinawa Centenarian Study. Age  200; 28: 313– 32. Google Scholar CrossRef Search ADS   15 Gibbs WW. Biomarkers and ageing: The clock-watcher. Nature  2014; 508: 168– 70. Google Scholar CrossRef Search ADS PubMed  16 Richmond RL, Law J, Kay-Lambkin F. Physical, mental, and cognitive function in a convenience sample of centenarians in Australia. J Am Geriatr Soc  2011; 59: 1080– 86. Google Scholar CrossRef Search ADS PubMed  17 Masui Y, Gondo Y, Inagaki H, Hirose N. Do personality characteristics predict longevity? Findings from the Tokyo Centenarian Study. Age  2006; 28: 353– 61. Google Scholar CrossRef Search ADS PubMed  18 Stathakos D, Pratsinis H, Zachos I et al.   Greek centenarians: assessment of functional health status and life-style characteristics. Exp Gerontol  2005; 40: 512– 18. Google Scholar CrossRef Search ADS PubMed  19 Samuelsson SM, Alfredson BB, Hagberg B et al.   The Swedish Centenarian Study: a multidisciplinary study of five consecutive cohorts at the age of 100. Int J Aging Hum Dev  1997; 45: 223– 53. Google Scholar CrossRef Search ADS PubMed  20 Randall GK, Martin P, Bishop AJ, Johnson MA, Poon LW. Social resources and change in functional health: comparing three age groups. Int J Aging Hum Dev  2012; 75: 1– 29. Google Scholar CrossRef Search ADS PubMed  21 Davey A, Elias MF, Siegler IC et al.   Cognitive function, physical performance, health, and disease: norms from the Georgia centenarian study. Exp Aging Res  2010; 36: 394– 425. Google Scholar CrossRef Search ADS PubMed  22 von Berenberg P, Drager D, Zahn T, Neuwirth J, Kuhlmey A, Gellert P. Chronic conditions and use of health care service among German centenarians. Age Ageing  2017; 46: 939– 45. Google Scholar CrossRef Search ADS PubMed  23 Wang B, He P, Dong B. Associations between social networks, social contacts, and cognitive function among Chinese nonagenarians/centenarians. Arch Gerontol Geriatr  2015; 60: 522– 27. Google Scholar CrossRef Search ADS PubMed  24 Giraldo G. Counting to 100 :A first look at Cuba's National Centenarian Study. MEDICC Rev  2009; 11: 17– 19. Google Scholar PubMed  25 Wang L, Li Y, Li H et al.   Regional aging and longevity characteristics in China. 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EQ-5D: a measure of health status from the EuroQol Group. Ann Med  2001; 33: 337– 43. Google Scholar CrossRef Search ADS PubMed  36 Price DD, McGrath PA, Rafii A, Buckingham B. The validation of visual analogue scales as ratio scale measures for chronic and experimental pain. Pain  1983; 17: 45– 56. Google Scholar CrossRef Search ADS PubMed  © The Author(s) 2018; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Epidemiology Oxford University Press

Cohort Profile: The China Hainan Centenarian Cohort Study (CHCCS)

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Publisher
Oxford University Press
Copyright
© The Author(s) 2018; all rights reserved. Published by Oxford University Press on behalf of the International Epidemiological Association
ISSN
0300-5771
eISSN
1464-3685
D.O.I.
10.1093/ije/dyy017
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Abstract

Why was the cohort set up? The proportion of the world population aged 60 years or over is expected to increase from 12% in 2013 to 21% in 2050. This increase will represent more than 2 billion elderly individuals, including 400 million people aged 80 years or older and 3.4 million centenarians in 2050.1 The population of individuals of advanced ages, including near-centenarians and centenarians, has become the fastest-growing segment of the population.2 This growth has led to considerable concern about the social and economic burden of disease and disability in this age group, for the oldest old are vulnerable to multiple age-related chronic conditions and disabilities and are at a high risk of losing their independence.3 Previous studies have indicated that exceptional longevity does not result in excessive levels of disability.4,5 In fact, some centenarians experience a delayed onset of age-related illnesses (delayers), whereas others do not succumb to any age-related illnesses (escapers).6 In addition, one case-control study showed that older individuals had a delayed age of onset of cancer, cardiovascular disease, diabetes mellitus, hypertension and osteoporosis than their respective younger reference groups.7 Thus, centenarians may represent a prototype of successful ageing.8 However, a Danish centenarian study identified only one physically healthy centenarian in a sample of over 200 participants9 and indicated that whether centenarians represent a model of successful ageing is still under scientific debate.10 Thus, studies on groups of centenarians can provide valuable information for the early prevention of major diseases, premature ageing and early death, thus providing the scientific support necessary to cope with the quickly approaching arrival of an ageing society in China. Longevity research has shown that no single factor contributes to reaching an exceptionally high age or to differences in survival. Previous research on centenarians has primarily examined biological indicators or medical aspects,11–15 and relatively little sociological, psychological or functional research has been undertaken with centenarians. However, data are currently available from Australian,16 Japanese,17 Hungarian, Greek,18 Swedish,19 American,10,20,21 German22 and Chinese23 studies. However, most of these studies provide evidence from developed countries. In contrast, very old individuals, including centenarians, in developing countries remain an under-studied and under-served population. In addition, only a few studies extensively examine data from medical, psychological and sociological domains simultaneously. Furthermore, the uncertain representativeness of centenarians and the lack of participant age verification in some studies make it difficult to draw reliable conclusions about this population.24 Therefore, we organized an interdisciplinary research team consisting of geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, nurses, a psychologist, a sociologist and epidemiologists to conduct a longitudinal observational study that targeted the population aged 100 years or older in Hainan, China. Hainan province has one of the highest life expectancies in China (76.3 years in 2010) and was authorized by the International Expert Committee on Population Aging and Longevity as ‘World Longevity Island’ on 27 August 2014 for its highest percentage of centenarians (18.75/100 000) in China.25 Most centenarians are indigenous and have lived on this island for their entire lives; thus, this population provided a steady gene pool for longevity-related genetic research. Based on this prospective community-based study, the China Hainan Centenarian Cohort Study (CHCCS) was established with three main objectives. The first objective is to evaluate the centenarians’ physical and mental health status as well as their social conditions, which are especially important in a developing country such as China, where broad economic constraints lead to numerous hardships. The second goal is to propose strategies to solve problems identified during this study. For example, participants with previously undetected health problems are referred to appropriate local health care providers after we have interviewed them and identified their needs. The third goal is to establish healthy ageing indicators that could be used to plan and conduct population-wide health interventions in the future. Who are the participants in the cohort? The CHCCS was designed as a complete sample study. The base study population of the CHCCS comprised male and female individuals aged 100 years or older throughout the Hainan provincial area (Figure 1). In total there were 1811 living centenarians, according to the household register provided by the civil affairs bureau in 2014. According to contact addresses from June 2014 to December 2016, 1473 living centenarians in 18 cities and counties of Hainan province were involved in CHCCS. The following inclusion criteria were used to recruit study participants: (i) was 100 years or older by 1 June 2014; (ii) volunteered to participate in the study and provided written informed consent; and (ii) was conscious and could cooperate to complete the questionnaire interview, physical health examination and blood tests. The following were participant exclusion criteria: (i) personal identity information was not complete or ID card showed an age of less than 100 years; (ii) refused to comply with the requirements of the study, including the collection of physical or biological samples. Table 1 shows the distribution of centenarians in Hainan province and the centenarians involved in the CHCCS. Table 1 The distribution of centenarians in Hainan and the sample size in CHCCS Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Table 1 The distribution of centenarians in Hainan and the sample size in CHCCS Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Locations  Centenarians in the registry  Centenarians who could be reached  Centenarians who consented to participate  North   Lingao  231  189  158   Haikou  327  281  202   Chengmai  202  154  95   Danzhou  202  122  47  Central   Wuzhishan  15  15  14   Baisha  15  12  9   Ding’an  49  43  30   Tunchang  31  28  21   Qiongzhong  17  14  12   Baoting  17  14  11  East   Wanning  173  147  83   Qionghai  66  61  55   Wenchang  182  155  82  West   Changjiang  45  44  41   Dongfang  46  42  39   Ledong  81  61  42  South   Sanya  48  43  38   Lingshui  64  48  23  Total  1811  1473  1002  Figure 1 View largeDownload slide Location of Hainan province, with 1811 living centenarians in 2014. Figure 1 View largeDownload slide Location of Hainan province, with 1811 living centenarians in 2014. To ensure the quality of the data and to prevent participants from overstating their ages, an age verification process was conducted before the participants were included in the study. Figure 2 shows the age validation process. It was an unprecedented challenge to recruit an entire sample of centenarians for an epidemiological study that included a detailed questionnaire and an extended clinical examination. Therefore, support from the Department of Civil Affairs of Hainan Province was critical, since this department has the household register of the indigenous elderly population and is responsible for providing monthly subsidies for individuals over 80 years of age. With their help, we were able to obtain a detailed list of centenarians throughout Hainan, containing their demographic and residential information. In addition, the Department of Civil Affairs of Hainan Province announced that each subordinate unit of the municipal and prefectural level would offer additional assistance, such as connecting with the indigenous centenarians and convening them for our study. Figure 2 View largeDownload slide Age validation process of centenarians in CHCCS. Figure 2 View largeDownload slide Age validation process of centenarians in CHCCS. To capture a wide range of health indicators within this age group and to allow them to conveniently participate in this programme, the eligible individuals were given the choice of completing the interview and examination either at home or in the community health service centres (public clinics). The home-based option was mainly for participants who were unable to transport themselves to the clinic or who lived far from the clinics. The clinic-based option required mobility of the participants. Several participants gathered in clinics nearby; thus, the multi-specialty medical group could conduct the survey and examination with a larger group of centenarians, which allowed for greater efficiency and organization of data collection. The pilot study was initiated in January 2014, and baseline interviews and examinations were subsequently conducted. This process was separated into two phases: Phase 1 and Phase 2, conducted from July 2014 to November 2015 and from March 2016 to December 2016, respectively. Baseline surveys were suspended during the winter because the participants were potentially vulnerable to the Hainan climate. Figures 3 and 4 show the participant recruitment and study scheme. The researchers obtained ethics approval from the Ethics Committee of the Chinese People’s Liberation Army General Hospital (Beijing, China). Each participant provided written informed consent to be included in the study. Figure 3 View largeDownload slide Participant recruitment in CHCCS. Figure 3 View largeDownload slide Participant recruitment in CHCCS. Figure 4 View largeDownload slide Study scheme in CHCCS. Figure 4 View largeDownload slide Study scheme in CHCCS. What was measured? The CHCCS baseline assessment consisted of a self-administered questionnaire with face-to-face interview, interdisciplinary examinations and a laboratory analysis. To permit valid comparisons with other studies, including the CKB,26 CLHLS,27 CHARLS28 and national and international epidemiological studies of centenarian populations, the CHCCS deliberately used standardized and validated instruments for data collection (Table 2). These instruments were pre-tested on a convenience sample of 48 centenarians who resided in Sanya suburb, and the instruments were slightly simplified before the procedure began. For the interview and examination, participants were visited at their residences or nearby clinics by a well-trained interdisciplinary medical group. The interview was performed by native nurses who were trained in interviewing older persons and spoke the local dialect. The interview session required approximately 45 min to complete, depending on each subject’s status, including visual and hearing acuity and cognitive function. Table 2 Contents of the baseline data collection in CHCCS Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Table 2 Contents of the baseline data collection in CHCCS Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Components  Measurements  Face-to-face interview   Sociodemographics  Marital status, occupation, education level, composition of household, personality   Functional capacity  Unintentional weight loss, vision and hearing, basic and instrumental activities of daily living (ADLs29 and IADLs)30   Cognitive function  Mini-Mental State Examination (MMSE)31   Mental health  Geriatric Depression Scale (GDS-15),32 WHO-5 Well-Being Index,33 stress, sense of isolation   Behaviours  Smoking and passive smoking, alcohol consumption, tea consumption, physical activity, sexual life   Habitual diet  11-item Semi-Quantitative Food Frequency Questionnaire   Sleep quality  Pittsburgh Sleep Quality Index (PSQI)34   Quality of life  EQ-5D35   Family information  Family structure, family harmony, family disease history   Social support/relations  Subsidy, social networks, social activity, companionship, reciprocity   Environment  Drinking water supply, occupational exposure, passive smoking exposure, cooking and heating fuels   Economic status  Previous and current income   Health service use  Outpatient attendance, emergency treatment, hospitalization, health insurance coverage   Reproductive history  Age of menarche, menstrual history, pregnancy history, hormone replacement therapy history  Medical/clinical examination   Health conditions  Medical and surgical history, comorbidity, medication   Anthropometric measurement  Weight, height, demi-span, waist, hip, thigh, calf, biceps circumference   Falls  Fall history, location and outcomes   General pain  Visual analogue scale (VAS)36   Physical function  Timed up-and-go test, chair standing, one-leg standing, grip strength   Physical examination  Resting blood pressure, heart rate, auscultation heart and lung, visual and hearing acuity, detect pitting ankle oedema, joint movement, spinal formation, cervical, axillary and inguinal lymph nodes   Electrocardiogram (ECG)  12-lead ECG   Ultrasonography  Carotid, thyroid, cardiac, pleural, visceral, femoral, calf ultrasonic examination   Dental examination  Tooth count, degree of mouth cleaning, periodontal disease  Biological specimens   Blood analysis  Fasting blood test and DNA sampling   Saliva DNA  Production, component and DNA of saliva   Hair analysis  Trace elements detection   Faeces examination  Morphology of faeces, intestinal flora detection via 16S rRNA sequence and whole-genome sequence analysis   Gynaecological check-up  ThinPrep cytology test (TCT)  Data collection on participants in the CHCCS (Table 3) began with a brief introduction and informed consent for both the procedure and DNA banking. After participants signed the consent form, 8 ml of fasting blood was drawn from participants by experienced nurses using four vacutainer tubes (2 ml each), two of which were purple-top anticoagulant tubes containing ethylenediaminetetraacetic acid (EDTA) and two of which were yellow-top serum-separating tubes (SST). After obtaining a fasting blood sample, subjects were given a free breakfast and then prepared to complete the interview and the rest of the physical examination. Using a face-to-face interview in the appropriate regional dialect, the interviewers recorded detailed information on the standardized structured questionnaire, including sociodemographics, personal and family disease histories, functional status, cognitive and mental health status, lifestyles, diet, sleep quality, leisure and physical activities, economic status, social support, health service use and reproductive histories (for females only). Then clinical examinations were conducted by the study group, including the measurement of blood pressure, anthropometric indices, geriatric syndromes and visual and hearing acuity as well as the administration of 12-lead electrocardiography, ultrasonography, an equipped dental examination and a gynaecological examination. The study group consisted of experienced geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, and trained nurses with average of 5 years of practice from the Hainan Branch of the Chinese PLA General Hospital. Biological specimens, including hair and saliva, were obtained and delivered to the hospital alongside blood and faeces samples, which were stored separately in refrigerated containers on the same day. Table 3 Summary of clinical measurements collected at baseline in CHCCS Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      a Evaluation of oral hygiene included dental plaque, odontolith, saprodontia and gums bleeding on probing. b White (leukocytes) and red blood cell (erythrocytes) counts, and platelets (thrombocytes). c Electrolytes, serum glucose, blood urea nitrogen, creatinine, serum calcium, serum total protein (TP), serum albumin, bilirubin, alkaline phosphatase (ALP), aspartate amino transferase (AST) and alanine amino transferase (ALT or SGPT). d Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. e Anti-cardiolipin antibody (ACL), complement component 4 (C4), immunoglobulin A (IgA), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM). f Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), cancer antigen 125 (CA 125), cancer antigen 19-9 (CA 19-9), cancer antigen 15-3 (CA 15-3), cancer antigen 724 (CA 724). g Estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), progesterone (PROG), testosterone (TES). Table 3 Summary of clinical measurements collected at baseline in CHCCS Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      Variables  Number of measurements  Equipment used  Method  Standing height  One  Manufactured instrument    Sitting height  One      Hip circumference  One  Standard tape measure  Around the maximal girth of the hips  Waist circumference  One    Horizontally around the smallest circumference between ribs and iliac crest, or at navel if no natural waistline  Weight  One      Resting pulse rate  Two  Omron HEM-7200    Resting blood pressure  Three  Omron HEM-7200  Seated blood pressure, 1 min apart, after a 3-min rest  12-lead electrocardiography (ECG)  One  GE MAC 5500  12-lead ECG was performed by specialized technicians  Ultrasonography  One  Philips CX50  Carotid, thyroid, cardiac, pleural, visceral, periumbilical fat, femoral, calf ultrasonic examinations were conducted by experienced sonographer  Audiometry  One  MADESEN Xeta    Equipped dental examinationa  One    Count teeth and evaluate oral hygiene and periodontal disease  Complete blood countb(CBC)  One  Sysmex XT4000i    Comprehensive metabolic panelc(CMP)  One  Roche cobas 8000    Lipid profiled  One      Markers of immune systeme  One      Markers of carcinomaf  One  Roche cobas 8000    Hormone testg    Roche cobas 8000    Hepatitis B antigen (HBsAg)  One      a Evaluation of oral hygiene included dental plaque, odontolith, saprodontia and gums bleeding on probing. b White (leukocytes) and red blood cell (erythrocytes) counts, and platelets (thrombocytes). c Electrolytes, serum glucose, blood urea nitrogen, creatinine, serum calcium, serum total protein (TP), serum albumin, bilirubin, alkaline phosphatase (ALP), aspartate amino transferase (AST) and alanine amino transferase (ALT or SGPT). d Total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides. e Anti-cardiolipin antibody (ACL), complement component 4 (C4), immunoglobulin A (IgA), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM). f Carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), cancer antigen 125 (CA 125), cancer antigen 19-9 (CA 19-9), cancer antigen 15-3 (CA 15-3), cancer antigen 724 (CA 724). g Estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), progesterone (PROG), testosterone (TES). How often has participant follow-up been conducted? Every centenarian was followed up through an annual telephone interview and electronic health records check. The annual follow-up purported to examine outcomes such as living conditions, new diseases, institutionalization, morbidity, sustainability of health behaviours and social participation, disability in instrumental and basic activities of daily living (ADLs), family support, main cause of death and migration. Telephone interviews were conducted by the study staff, and medical information was obtained from the centenarians, their relatives and village doctors. Electronic health records from the health care system and the household registration system of the public security were reviewed to confirm the cause of death or migration. The two follow-up approaches were used to confirm and complement each other, to ensure that the information was credible and comprehensive. What results have been found in the CHCCS? The number of province-registered centenarians was 1811 in February 2014. In June 2014, when the CHCCS began, the number of living centenarians available by register address was 1473. By December 2016, 268 centenarians had died, 203 refused to participate and 1002 agreed to participate in this study, and the response rate was 86.2% (Table 1). Centenarians who did and did not respond showed similar distribution in age and gender (P = 0.27 and 0.56 respectively, Table 4). Table 4 Participants and nonparticipantsa according to age and sex in CHCC Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    a Non-participants included those who had died, moved or declined the survey. b The chi-square test was used to examine the gender differences between dead and alive participants. c The chi-square test was used to examine the gender differences between non-participants and participants. d The t-test was used to examine age differences between non-participants and participants. Table 4 Participants and nonparticipantsa according to age and sex in CHCC Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    Characteristic  Total  Male  Female  P  Address known with age verified, n  1473  262  1211     Dead, n (%)  268  49 (18.2)  219 (81.7)  0.81b   Alive, n (%)            Refused or incapable  203  33 (16.2)  170 (83.7)  0.56c    Participants  1002  180 (18.0)  822 (82.0)    Age (mean ± standard deviation)        0.27d   Nonparticipants*  102.7±2.6  102.6±2.5  102.7±2.6     Participants  102.8±2.8  102.5±2.4  102.9±2.8    a Non-participants included those who had died, moved or declined the survey. b The chi-square test was used to examine the gender differences between dead and alive participants. c The chi-square test was used to examine the gender differences between non-participants and participants. d The t-test was used to examine age differences between non-participants and participants. Excluding centenarians with more than 25% missing data, the baseline sociodemographic characteristics of 990 CHCCS participants are shown in Table 5. The range of ages was 100-115 years among the centenarians, and their average age was 102.85±2.76 years (102.45±2.31 years for men and 102.94±2.84 years for women). A total of 81.9% (n = 811) of participants were women. Compared with men, women tend to be widowed (92.8%), be illiterate (96.5%), live together with families (87.5%) and have a body mass index (BMI) < 24.0 (96.7%). Table 5 Sociodemographic variables of the CHCCS participants in CHCCS Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Table 5 Sociodemographic variables of the CHCCS participants in CHCCS Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Mean±SD  All (n = 990)  Men (n = 179)  Women (n = 811)  P  Age (years)  102.85±2.76  102.45±2.31  102.94±2.84  0.030  Height (cm)  144.68±8.89  153.83±7.97  142.66±7.74  < 0.001  Weight (kg)  37.88±7.75  44.83±7.20  36.35±7.00  < 0.001  Waist circumference (cm)  75.9±22.44  76.89±8.27  75.68±24.49  0.515  N (%)          Age group (years)        0.083   100  194 (19.6)  40 (22.3)  154 (19.0)     101–104  581 (58.7)  111 (62.0)  470 (58.0)     ≥ 105  215 (21.7)  28 (15.6)  187 (23.0)    Ethnicity        0.620   Han  869 (87.8)  155 (86.6)  714 (88.0)     Li  105 (10.6)  22 (12.3)  83 (10.2)     Other  16 (1.6)  2 (1.1)  14 (1.7)    Marital status        < 0.001   Married  97 (9.8)  43 (24.0)  54 (6.7)     Widowed  885 (89.4)  132 (73.7)  753 (92.8)     Divorced or never married  8 (0.8)  4 (2.2)  4 (0.5)    Education level        < 0.001   Illiterate  902 (91.1)  119 (66.5)  783 (96.5)     Primary school  67 (6.8)  43 (24.0)  24 (3.0)     Middle school or higher  21 (2.1)  17 (9.5)  4 (0.5)    Residential type        0.048   Living together with family  854 (86.3)  144 (80.4)  710 (87.5)     Living alone at home  128 (12.9)  35 (19.6)  93 (11.5)     Pension agency  8 (0.8)  0 (0.0)  8 (1.0)    Body mass index (kg/m2)        < 0.001   Underweight (< 18.5)  644 (65.1)  88 (49.2)  556 (68.6)     Normal (18.5–24.0)  312 (31.5)  84 (46.9)  228 (28.1)     Overweight (24.0–27.9)  27 (2.7)  6 (3.4)  21 (2.6)     Obese (≥ 28.0)  7 (0.7)  1 (0.6)  6 (0.7)    Selected geriatric syndromes and self-reported chronic conditions among CHCCS participants are shown in Table 6. Geriatric syndromes and chronic conditions are two of our main areas of focus. A total of 27.5%, 30.7% and 22.0% centenarians reported vision impairment, hearing impairment, and dizziness, respectively. In addition, 6.9% fell more than three times in the previous month. Compared with men, women tended to report their health as bad (24.3% vs 16.7%) and more likely to be dependent (74.8% vs 58.7%, P < 0.05). The most common self-reported chronic condition was hypertension (23.2%). Table 6 Selected geriatric syndromes and self-reported chronic conditions in CHCCS participants   All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)      All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)    Table 6 Selected geriatric syndromes and self-reported chronic conditions in CHCCS participants   All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)      All (n = 990)  Men (n = 179)  Women (n = 811)  P  Self-reported vision impairment  272 (27.5)  36 (20.1)  236 (29.1)  0.015  Self-reported hearing impairment  304 (30.7)  61 (34.1)  243 (30.0)  0.280  Dizziness  218 (22.0)  36 (20.1)  182 (22.4)  0.496  Self-reported health        0.019   Excellent  1 (0.1)  1 (0.6)  0 (0.0)     Very good  154 (15.6)  32 (17.9)  122 (15.0)     Good  608 (61.4)  116 (64.8)  492 (60.7)     Bad  203 (20.5)  28 (15.6)  175 (21.6)     Particularly bad  24 (2.4)  2 (1.1)  22 (2.7)    Falls in past month        0.467   None  731 (73.8)  134 (74.9)  597 (73.6)     1  123 (12.4)  18 (10.1)  105 (12.9)     2  68 (6.9)  11 (6.1)  57 (7.0)     ≥ 3  68 (6.9)  16 (8.9)  52 (6.4)    Self-reported chronic conditions           Hypertension  230 (23.2)  39 (21.8)  191 (23.6)  0.613   Diabetes  52 (5.3)  6 (3.4)  46 (5.7)  0.208   Dyslipidaemia  4 (0.4)  2 (1.1)  2 (0.2)  0.096   Stroke  21 (2.1)  1 (0.6)  20 (2.5)  0.109   Cardiovascular disease  42 (4.2)  8 (4.5)  34 (4.2)  0.868   Cancer  1 (0.1)  1 (0.6)  0 (0.0)  0.033  Functional dependence        < 0.001   Overall dependence  282 (28.5)  43 (24.0)  239 (29.5)     Dependent  430 (43.4)  62 (34.6)  368 (45.4)     Independent  278 (28.1)  74 (41.3)  204 (25.2)    What are the main strengths and weakness of the CHCCS? Hainan province has the highest density of centenarians and the highest longevity index in China. Furthermore, it has an independent sea island area that is relatively closed and has a low proportion of immigrants. Therefore, there is a high homogeneity of centenarians, which made it relatively easy to achieve the goals of our study. Second, the CHCCS is supported by the government of Hainan province; thus, sampling, household surveys and an electronic medical records check can be guaranteed, minimizing the loss of participants at follow-up. Third, the interdisciplinary research team of the CHCCS is composed of geriatricians, cardiologists, an otolaryngologist, dentists, gynaecologists, a sonographer, nurses and epidemiologists. This team evaluated the centenarians’ health situation and studied the mechanisms of longevity. Further, by relying on the Chinese PLA General Hospital (the largest hospital in Hainan province), we collected various biomarkers covering almost every organ and system of the body. Furthermore, the blood samples were numbered and reserved using the standard system, which is conducive to future studies of this population. The high age of participants in the CHCCS suggests that a sufficient number of incident outcome events can be expected within a relatively short time period. The results from the CHCCS and its subgroup of relevant nested case-control studies can be expected within a short time frame. However, several limitations must be mentioned. Our subjects are unlikely to be completely representative of the centenarians of China, so the generalizability of the results is limited. Second, we cannot rule out the possibility of healthy volunteer bias among centenarians who chose to participate in the study. Third, we cannot exclude the possibility of recall bias during the data collection process, although we asked the same questions of participants and their relatives for reliability checking. Fourth, even with the support of the Hainan government, we cannot rule out the possibility of withdrawal bias in the annual follow-up of this large sample of centenarians. Can I obtain the data? Where can I learn more? Although there is no immediate plan to make the data freely available in the public domain, specific proposals for further collaboration are welcome. For further information, please contact the corresponding authors via e-mail: [yhe301@x263.net] or [baisui301@163.com]. The China Hainan Centenarian Cohort Study (CHCCS) profile in a nutshell CHCCS is a cohort of a complete sample for individuals aged 100 years or older throughout the China Hainan provincial area. CHCCS has three goals. The first goal is to evaluate the centenarians’ physical and mental health status as well as their social conditions, which are especially important in a developing country such as China, where broad economic constraints lead to numerous hardships. The second goal is to propose strategies to solve problems identified during this study. For example, participants with previously undetected health problems are referred to appropriate local health care providers after we have interviewed them and identified their needs. The third goal is to establish healthy ageing indicators that could be used to plan and conduct population-wide health interventions in the future. A total of 1002 centenarians were recruited at baseline, 2014-16, from China, Hainan provincial area. The dataset comprises a wide range of variables (911 from questionnaire; 719 from interdisciplinary examinations and a laboratory analysis). These include: demographic characteristics; anthropometric measures; socioeconomic status; lifetime lifestyle; present medical history; family medical history; health outcomes; biological samples including blood and DNA; and cognitive function measures etc. Specific proposals for collaboration are welcomed. Further information can be found via e-mail to [yhe301@x263.net] or [baisui301@163.com]. Acknowledgements We thank the Department of Civil Affairs of Hainan Province for connecting with and convening the centenarians. The CHCCS investigators include the following: the Hainan Branch of Chinese PLA General Hospital: J Li, XP Chen, Q Zhu, F Zhang, Y L Zhao (Co-PI) and F X Luan (Co-PI); the Institute of Geriatrics, Chinese PLA General Hospital: SS Yang, Y Yao, J Li, M Liu, J H Wang, X Y Li and Y He (Co-PI). 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International Journal of EpidemiologyOxford University Press

Published: Feb 28, 2018

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