Association between duration of oral contraceptive use and risk of hypertension: A meta‐analysis, methodological and statistical issues

Association between duration of oral contraceptive use and risk of hypertension: A... To the EditorI read the study conducted by Liu et al that was published in the Journal of Clinical Hypertension. The authors tried to evaluate the effect of oral contraceptive duration on hypertension risk, as well as assess the possible dose‐response relationship between oral contraceptive duration and hypertension risk. I think some issues on methodological pattern needs to be considered.First, the study selection and characteristics has been reported by Figure 1. Of total 6227 retrieved reported articles (6222: left box and 5: right box), 5922 articles were excluded. Therefore, 305 articles is expected to be considered for abstract screening; however, this was 3266. Moreover, considering eligibility box, even if we accept 25 full text articles remains for named section, after excluding 16 articles (third exclusion box on right side), the number of eligible articles for final meta‐analysis reaches to 9. While 17 full articles were selected.Second, Table 1 shows detailed characteristics of the included studies, but unfortunately there are egregious errors. For example, for the first study in the list, which was published by Chiu et al the following comments needs to be addressed:The total past oral contraceptive users sample size of the referenced study was (25 780; 48‐58 years = 10 647; 58‐66 years = 9213; and ≥67 years = 5920), which is different from the reported sample size by Liu et alAuthors abbreviate NA (not available) for “adjustment for covariate” part, while in the referenced study, authors clearly mentioned “odds ratios were adjusted for demographic and lifestyle factors that were significantly associated with treatment for high blood pressure in univariate analysis. Namely, income, country of origin, BMI, smoking, alcohol, exercise, family history of high blood pressure, menopausal hormone therapy use, number of children, whether they breastfed, and age of menopause, with additional categories for missing values (see page 5, methods).The reported adjusted OR (odds ratio) in the main article for each age category was (48‐58 years, 1.1; 58‐66 years, 0.9; and ≥ 67 years, 0.9), which is different from the one in Liu et alThird, the Homogenization methodology of reported OR, hazard ratio (HR) or relative risks (RR) of different studies was not described. The same errors were also detected in other reported studies.Considering these points; which have direct effect on the final conclusion, are important.CONFLICT OF INTERESTThe author reports no conflicts of interest.REFERENCESLiu H, Yao J, Wang W, Zhang D. Association between duration of oral contraceptive use and risk of hypertension: a meta‐analysis. J Clin Hypertension. 2017;19:613‐613.Chiu CL, Lind JM. Past oral contraceptive use and self‐reported high blood pressure in postmenopausal women. BMC Public Health. 2015;15:54. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Clinical Hypertension Wiley

Association between duration of oral contraceptive use and risk of hypertension: A meta‐analysis, methodological and statistical issues

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Publisher
Wiley
Copyright
Copyright © 2018 Wiley Periodicals, Inc.
ISSN
1524-6175
eISSN
1751-7176
D.O.I.
10.1111/jch.13208
Publisher site
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Abstract

To the EditorI read the study conducted by Liu et al that was published in the Journal of Clinical Hypertension. The authors tried to evaluate the effect of oral contraceptive duration on hypertension risk, as well as assess the possible dose‐response relationship between oral contraceptive duration and hypertension risk. I think some issues on methodological pattern needs to be considered.First, the study selection and characteristics has been reported by Figure 1. Of total 6227 retrieved reported articles (6222: left box and 5: right box), 5922 articles were excluded. Therefore, 305 articles is expected to be considered for abstract screening; however, this was 3266. Moreover, considering eligibility box, even if we accept 25 full text articles remains for named section, after excluding 16 articles (third exclusion box on right side), the number of eligible articles for final meta‐analysis reaches to 9. While 17 full articles were selected.Second, Table 1 shows detailed characteristics of the included studies, but unfortunately there are egregious errors. For example, for the first study in the list, which was published by Chiu et al the following comments needs to be addressed:The total past oral contraceptive users sample size of the referenced study was (25 780; 48‐58 years = 10 647; 58‐66 years = 9213; and ≥67 years = 5920), which is different from the reported sample size by Liu et alAuthors abbreviate NA (not available) for “adjustment for covariate” part, while in the referenced study, authors clearly mentioned “odds ratios were adjusted for demographic and lifestyle factors that were significantly associated with treatment for high blood pressure in univariate analysis. Namely, income, country of origin, BMI, smoking, alcohol, exercise, family history of high blood pressure, menopausal hormone therapy use, number of children, whether they breastfed, and age of menopause, with additional categories for missing values (see page 5, methods).The reported adjusted OR (odds ratio) in the main article for each age category was (48‐58 years, 1.1; 58‐66 years, 0.9; and ≥ 67 years, 0.9), which is different from the one in Liu et alThird, the Homogenization methodology of reported OR, hazard ratio (HR) or relative risks (RR) of different studies was not described. The same errors were also detected in other reported studies.Considering these points; which have direct effect on the final conclusion, are important.CONFLICT OF INTERESTThe author reports no conflicts of interest.REFERENCESLiu H, Yao J, Wang W, Zhang D. Association between duration of oral contraceptive use and risk of hypertension: a meta‐analysis. J Clin Hypertension. 2017;19:613‐613.Chiu CL, Lind JM. Past oral contraceptive use and self‐reported high blood pressure in postmenopausal women. BMC Public Health. 2015;15:54.

Journal

Journal of Clinical HypertensionWiley

Published: Jan 1, 2018

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