[Trials of primary prevention by diet or hypolipidemic treatment].

The experimental demonstration of a causal relationship between serum cholesterol and coronary artery disease has been confirmed by primary prevention trials. Four trials have fulfilled the methodological criteria of this type of research. Three of them have involved lipid lowering drugs (clofibrate, cholestyramine and gemfibrozil) and the fourth a diet low in saturated fats. They were undertaken in middle aged hypercholesterolemic men and offered 9 out of 10 chances of demonstrating a significant reduction in the prevalence in ischaemic heart disease if it existed. The serum cholesterol of the treatment groups was on average 8 to 13% lower to that of the control groups. In the 4 trials, the prevalence of severe coronary events, infarction and sudden death, was significantly reduced (relative reduction of 19 to 47%). The reduction in individual risk was proportional to the reduction in serum cholesterol. In 2 trials, this reduction was related to variations in the opposite directions of the LDL and HDL cholesterol: a reduction of 1% in LDL-cholesterol reduced the risk by 2% and an increase of 1% of HDL-cholesterol reduced it by 2 to 4%. None of the trials were designed to evaluate the effect of intervention on mortality. In one of them (clofibrate), all cases of mortality were temporarily increased during the trial.(ABSTRACT TRUNCATED AT 250 WORDS)