Risk factors for cardiovascular disease in rural South India: cohort study

BACKGROUND AND OBJECTIVES: Cardiovascular diseases (CVD) accounted for one-third of the deaths in India. We conducted a cohort study to estimate the incidence of CVD and the association of established risk factors with the incident CVD in a rural population in South India. DESIGN, SETTING AND PARTICIPANTS: We conducted a community-based cohort study among 6026 adults aged 25–64 years in five villages in Tiruvallur, Tamil Nadu. We did baseline (2005–2007) and two follow-up surveys in 2008–2009 and 2013–2015. Risk factors studied were tobacco, alcohol, hypertension, self-reported diabetes and central obesity. OUTCOME MEASURES: Outcome measures were fatal or non-fatal ischaemic heart disease or cerebrovascular event. We estimated HRs for the risk factors and population attributable fraction (PAF). RESULTS: We followed up 5641 (94.4%) subjects, and follow-up duration was 33 371 person years. The overall incidence of cardiovascular event or death was 4.6 per 1000 person years. Current smoking (HR 1.6, 95% CI 1.1 to 2.6) and hypertension (HR 2.2, 95% CI 1.5 to 3.4) were the risk factors among men and accounted for 47% of the PAF. Among women, hypertension (HR 1.8, 95% CI 1.0 to 3.4), self-reported diabetes (HR 4.3, 95% CI 2.2 to 8.1) and central obesity (HR 2.2, 95% CI 1.2 to 4.0) were associated with CVD and accounted for more than half of the PAF. CONCLUSIONS: We described the high burden of fatal CVD and identified the role of CVD risk factors such as hypertension, self-reported diabetes, smoking and central obesity. There is an urgent need to implement low-cost interventions such as smoking cessation and treat hypertension and diabetes in primary care settings.