Risk factors for cardiovascular diseases: is the social gradient reversing in northern India?

In the past century, most developed countries witnessed a reversal of social gradient in cardiovascular diseases. To examine whether this phenomenon is also under way in developing countries, we assessed the prevalence of selected risk factors for cardiovascular diseases among different social groups living in urban and rural areas of northern India.

Four hundred adults > or =30 years of age, selected by cluster sampling, were surveyed from 8 purposively selected communities of Chandigarh and Haryana during 2004-05. The WHO STEPS tool for surveillance of risk factors was used to enquire about sociodemographic characteristics, tobacco use, alcohol intake, physical activity and to measure weight, height, blood pressure, and waist and hip circumference. Prevalence of risk factors such as tobacco use, physical inactivity, overweight (BMI > or =25 kg/m2), and hypertension (> or = 140/90 mmHg or on anti-hypertension treatment) were estimated according to the area of residence and across educational categories after controlling for the effects of confounding variables.

The prevalence of hypertension in urban (39%; 95% CI 29.5%-49.2%), slum (35%; 95% CI 27.2%-42.9%) and rural (33%; 95% CI 25.4%-40.8%) communities was found to be statistically similar (p > 0.05) after controlling for age, gender and education. The prevalence of physical inactivity (17% v. 12%), central obesity (90% v. 88%), overweight (20% v. 19%) and hypertension (34% v. 36%), were found to be statistically similar among literate and illiterate population after controlling for the effect of age, sex and place of residence (p > 0.05). However, the risk of tobacco use was significantly lower among literates (OR 0.3, 95% CI 0.1-0.8).

In selected communities of northern India, most of the cardiovascular disease risk factors did not have a social gradient except tobacco use, which was more common in the lower social group.