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

Abstract

ObjectivesWe seek to investigate the joint effects of age and body mass index (BMI) on the incident hypertension subtypes among Chinese adults during 1989–2011. MethodsWe 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. ResultsNormotensive 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/m2, the RR of hypertension was 3.13 (95% CI, 2.84–3.45) in the group with BMI≥28kg/m2. 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. ConclusionsThe 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.