Association of 6-year waist circumference gain and incident hypertension

Objective The risk of incident hypertension with gain in waist circumference (WC) has not been fully addressed among Chinese adults. Methods A total of 10 265 non-hypertensive participants >= 18 years old who underwent health examinations in rural China were recruited in 2007-2008 and followed up in 2013-2014. Participants were classified by gender according to categories of per cent WC gain at follow-up: <=-2.5%, -2.5% to 2.5%, 2.5% to 5% and >5%. Relative risk (RR) and 95% CI values for effect of WC gain on the incident hypertension were calculated by using modified Poisson regression models. Results During 6 years of follow-up, we identified 2027 hypertension cases (1213 women). From baseline to follow-up, the prevalence of abdominal obesity increased from 21.1% to 29.6% for men and 49.8% to 61.9% for women. As compared with participants who were not abdominally obese at both baseline and follow-up, both genders who were abdominally obese at follow-up showed greater risk of hypertension regardless of abdominal obesity status at baseline. Compared with the reference group of -2.5% to 2.5% change in WC, with >5% WC gain, risk of incident hypertension was increased for men (RR=1.34, 95% CI 1.15 to 1.57) and women (RR=1.28, 95% CI 1.10 to 1.50). The hypertension risk decreased for men with WC loss >= 2.5% (RR=0.81, 95% CI 0.67 to 0.98). Conclusions Abdominal obesity is seriously prevalent in China. The risk of hypertension increased significantly with increasing WC for both genders in a rural Chinese population.