Prevalence and incidence of hypertension: Results from a representative cohort of over 16,000 adults in three cities of South Asia

Background Despite high projected burden, hypertension incidence data are lacking in South Asian population. We measured hypertension prevalence and incidence in the Center for cArdio-metabolic Risk Reduction in South Asia (CARRS) adult cohort. Methods The CARRS Study recruited representative samples of Chennai, Delhi, and Karachi in 2010/11, and socio-demographic and risk factor data were obtained using a standard common protocol. Blood pressure (BP) was measured in the sitting position using electronic sphygmomanometer both at baseline and two year follow-up. Hypertension and control were defined by JNC 7 criteria. Results In total, 16,287 participants were recruited (response rate = 94.3%) and two year follow-up was completed in 12,504 (follow-up rate = 79.2%). Hypertension was present in 30.1% men (95% CI: 28.7–31.5) and 26.8% women (25.7–27.9) at baseline. BP was controlled in 1 in 7 subjects with hypertension. At two years, among non-hypertensive adults, average systolic BP increased 2.6 mm Hg (95% CI: 2.1–3.1), diastolic BP 0.7 mm Hg (95% CI: 0.4–1.0), and 1 in 6 developed hypertension (82.6 per 1000 person years, 95% CI: 80.8–84.4). Risk for developing hypertension was associated with age, low socio-economic status, current alcohol use, overweight, pre-hypertension, and dysglycemia. Risk of incident hypertension was highest (RR = 2.95, 95% CI: 2.53–3.45) in individuals with pre-hypertension compared to normal BP. Collectively, 4 modifiable risk factors (pre-hypertension, overweight, dysglycemia, and alcohol use) accounted for 78% of the population attributable risk of incident hypertension. Conclusion High prevalence and poor control of hypertension, along with high incidence, in South Asian adult population call for urgent preventive measures.