Joint effects of age and body mass index on the incidence of hypertension subtypes in the China Health and Nutrition Survey: A cohort study over 22 years

Objectives. We seek to investigate the joint effects of age and body mass index (BMI) on the incident hypertension subtypes among Chinese adults during 1989-2011. Methods. We investigated the Incidence rates (IRs, per 100 person-years) of hypertension subtypes, adjusted relative risks (RRs) and population attributable risk percent (PAR%) of BMI for hypertension, and clarified the age-specific effect of BMI on incident hypertension utilizing a dynamic cohort study from the China Health and Nutrition Survey (CHNS) 1989-2011. Results. Normotensive participants (n=53,028) at baseline were included, with mean age was 41.7 (95% CI, 41.6-41.7) years old. During a total of 118,694 person years (average was 6.38 years) of follow-up, a total of 5208 incident cases of hypertension were documented. The IRs of hypertension were 4.4 (95% CI, 4.3-4.5), which increased gradually by age and BMI (P-trend < 0.001). Compared with those with BMI < 22 kg/m(2), the RR of hypertension was 3.13 (95% CI, 2.84-3.45) in the group with BMI >= 28 kg/m(2). The PAR% (BMI > 22 vs. BMI < 22) for hypertension in Chinese population was 32% (95% CI, 29-34%). Similar trends were observed in all age and BMI groups for both isolated systolic hypertension and systolic-diastolic hypertension, which were mainly affected by age. In contrast, the peak IR of isolated diastolic hypertension was observed in participants aged 30-49 years with higher BMIs. Conclusions. The PAR% (IR of BP >= 140/90 or treatment for BMI > 22 vs. IR for BMI < 22) of elevated body weight for hypertension was 32% in Chinese population. (C) 2016 Elsevier Inc. All rights reserved.