Age-related modification effect on the association between body mass index and the risk of hypertension: A Cohort Study on Chinese people living in the rural areas / 中华流行病学杂志

Objective: To study the modification effect of age on the association between body mass index and the risk of hypertension. Methods: People age ≥18 years old were selected by clusters, from a rural area of Henan province. In total, 20 194 people were recruited at baseline during 2007 and 2008, and the follow-up study was completed from 2013 to 2014. Logistic regression model was used to assess the risk of incident hypertension by baseline BMI and age-specific BMI. Results: During the 6-year follow-up period, 1 950 hypertensive persons were detected, including 784 men and 1 166 women, with cumulative incidence rates as 19.96%, 20.51%, and 19.61%, respectively. Compared with those whose BMI<22 kg/m(2), the RRs of hypertension were 1.09 (0.93-1.27), 1.17 (1.01-1.37), 1.34 (1.14-1.58) and 1.31 (1.09-1.56) for participants with BMI as 22-, 24-, 26- and ≥28 kg/m(2), respectively. In young and middle-aged populations, the risk of hypertension gradually increased with the rise of BMI (trend P<0.05). However, in the elderly, the increasing trend on the risk of hypertension risk was not as significantly obvious (trend P>0.05). Conclusion: The effect of BMI on the incidence of hypertension seemed to depend on age. Our findings suggested that a weight reduction program would be more effective on young or middle-aged populations, to prevent the development of hypertension.

A cohort study on body mass index and risk of all-cause mortality among hypertensive population / 中华流行病学杂志

Objective: To investigate the relationship between body mass index (BMI) and all-cause mortality in hypertensive population. Methods: All participants were selected from a prospective cohort study based on a rural population from Henan province, China. Cox proportional hazards regression models were used to estimate the associations of different levels of BMI stratification with all-cause mortality. Restricted cubic spline models were used to detect the dose-response relation. Results: Among the 5 461 hypertensive patients, a total of 31 048.38 person-years follow-up was conducted. The median of follow-up time was 6 years, and 589 deaths occurred during the follow-up period. Compared to normal weight group (18.5 kg/m(2)<BMI<24.0 kg/m(2)) the multivariate-adjusted hazard ratios for all-cause mortality associated with BMI levels (<18.5 kg/m(2), 24-28 kg/m(2), and ≥28 kg/m(2)) were 0.83 (95%CI: 0.37-1.87), 0.81 (95%CI: 0.67-0.97), and 0.72 (95%CI: 0.56-0.91), respectively. The dose-response analysis showed a nonlinear, reverse "S" shaped relationship (non-linearity P<0.001). Conclusion: Overweight or obese might have a protective effect on all-cause mortality in hypertensive population, which supports the "obesity paradox" phenomenon.