The Lipid Research Clinics Coronary Primary Prevention Trial results. II. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering

Abstract

In the Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT), a 19% lower incidence of coronary heart disease (CHD) in cholestyramine-treated men was accompanied by mean falls of 8% and 12% in plasma total (TOTAL-C) and low-density lipoprotein (LDL-C) cholesterol levels relative to levels in placebo-treated men. When the cholestyramine treatment group was analyzed separately, a 19% reduction in CHD risk was also associated with each decrement of 8% in TOTAL-C or 11% in LDL-C levels (P less than .001). Moreover, CHD incidence in men sustaining a fall of 25% in TOTAL-C or 35% in LDL-C levels, typical responses to the prescribed dosage (24 g/day) of cholestyramine resin, was half that of men who remained at pretreatment levels. Adherence to medication was associated with reduced incidence of CHD only when accompanied by falls in TOTAL-C and LDL-C levels. Small increases in high-density lipoprotein cholesterol levels, which accompanied cholestyramine treatment, independently accounted for a 2% reduction in CHD risk. Thus, the reduction of CHD incidence in the cholestyramine group seems to have been mediated chiefly by reduction of TOTAL-C and LDL-C levels.