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 22years.

<bold>Objectives: </bold>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.<bold>Methods: </bold>We investigated the Incidence rates (IRs, per 100person-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.<bold>Results: </bold>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 118,694person years (average was 6.38years) 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 (Ptrend<0.001). Compared with those with BMI<22kg/m(2), the RR of hypertension was 3.13 (95% CI, 2.84-3.45) in the group with BMI≥28kg/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 30-49years with higher BMIs.<bold>Conclusions: </bold>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. [ABSTRACT FROM AUTHOR]