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 2.6mm Hg (95% CI: 2.1-3.1), diastolic BP 0.7mm 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.