SERUM-CHOLESTEROL AND CORONARY-ARTERY DISEASE IN POPULATIONS WITH LOW-CHOLESTEROL LEVELS - THE INDIAN PARADOX

Objective: To examine the relation between serum cholesterol and coron ary artery disease prevalence below the range of cholesterol values ge nerally observed in developed countries. Design and Setting: Cross-sec tional survey of two randomly selected villages from Moradabad distric t and 20 randomly selected streets in the city of Moradabad. Subjects and methods: 3575 Indians, aged 25-64 years including 1769 rural (894 men, 875 women) and 1806 urban (904 men, 902 women) subjects. The surv ey methods were questionnaires, physical examination and electrocardio graphy, Results: The overall prevalences of coronary artery disease we re 9.0% in urban and 3.3% in rural subjects and the prevalences were s ignificantly (P<0.001) higher in men compared to women in both urban ( 11.0 vs. 6.9%) and rural subjects (3.9 vs. 2.6%). The average serum ch olesterol concentrations were 4.91 mmol/l in urban and 3.22 mmol/l in rural subjects without any sex differences. The prevalences of coronar y artery disease were significantly higher among subjects with low and high serum cholesterol concentration compared to subjects with very l ow cholesterol and showed a positive relation with serum cholesterol w ithin the range of serum cholesterol level studied in both rural and u rban in both sexes. Among subjects with low serum cholesterol, there w as a higher prevalence of coronary risk factors, hypertension, diabete s, obesity and sedentary lifestyle. Serum cholesterol level showed a s ignificant positive relation with low density lipoprotein cholesterol and triglycerides in all the four subgroups. Logistic regression analy sis after pooling of data from both rural and urban, with adjustment o f age showed that low serum cholesterol level (odds ratio: men 0.96, w omen 0.91) had a positive strong relation with coronary artery disease and there was no evidence of any threshold. Diabetes mellitus (men 0. 73, women 0.74) and sedentary lifestyle (men 0.86, women 0.74) were si gnificant risk factors of coronary disease in both sexes. Hypertension (men 0.82, women 0.64) and smoking (men 0.81, women 0.52) were weakly associated with coronary disease in men but not in women. Conclusion: Serum cholesterol level was directly related to prevalence of coronar y artery disease even in those with low cholesterol concentration (<5. 18 mmol/l). It is possible that some Indian populations may benefit by increased physical activity and decline in serum cholesterol below th e range of desired serum cholesterol in developed countries. (C) 1998 Elsevier Science Ireland Ltd.