Prevalence of coronary artery disease and its risk factors in the urban population of South and North India.

There is scanty evidence on prevalence of coronary artery disease (CAD) in the urban population of India and it is not clear why South Indians have higher prevalence than North Indians. Of 506 subjects between 25-65 years of age selected for this study from 234 randomly selected households from 2 randomly selected streets, 46 (9.0%) were non-responders and 460 (response rate 91%) volunteered to participate in the study. Dietary intakes, anthropometric and laboratory data, prevalence of risk factors and CAD were obtained and compared with 152 North Indian subjects reported earlier. In comparison with North Indians, the prevalence of CAD was 61.6% higher in South Indians (13.9 vs 8.6%). The prevalence of possible evidence of CAD in South Indians was 139 per 1000 (95% confidence limits 112 to 178). While prevalence of diabetes mellitus, glucose intolerance, hypertension, hypercholesterolemia, hypertriglyceri-demia were comparable between North and South Indians in both sexes, the prevalence of smoking in South Indians males (44.6%) was significantly higher than North Indian. The prevalence of passive smoking in females (45.3%) was significantly higher in South Indian females which may be the cause of higher CAD among them. While total fat intake in North and South Indians were comparable, the intake of saturated fat and cholesterol were higher and P/S ratio was lower than North Indians, although these levels of fat intake are considered safe in British who have 26.4% less prevalence of CAD than South Indians. Among smokers, those subjects eating low saturated fat diet had less CAD compared to those smokers eating higher fat diet. It is clear that smoking, saturated fat, cholesterol, hypertension, diabetes, central obesity and glucose intolerance alone can not explain the cause of all of the higher CAD among South Indians. Study of other risk factors such as insulin resistance and antioxidant vitamins may be necessary.