Baseline risk factors and their association with outcome in the West of Scotland Coronary Prevention Study. The West of Scotland Coronary Prevention Study Group

Abstract

The West of Scotland Coronary Prevention Study recently demonstrated the benefits of pravastatin therapy in the prevention of coronary heart disease events in middle-aged hypercholesterolemic men without prior myocardial infarction. We present an analysis of the influence of baseline risk factors on coronary events and total mortality in the trial, and their interaction with therapy, using the Cox proportional hazards model. The multivariate predictors of fatal or nonfatal coronary events were treatment allocation (pravastatin or placebo), current smoking, diabetes mellitus, nitrate consumption, minor electrocardiographic abnormalities, angina pectoris, family history of premature coronary death, widowhood, blood pressure, and total cholesterol/high density lipoprotein cholesterol ratio. Independent of other risk factors, pravastatin reduced the risk of definite coronary heart disease death or nonfatal myocardial infarction by 32% (95% confidence interval 17 to 44, p = 0.0001), definite or suspected coronary heart disease death by 35% (3 to 56, p = 0.035), cardiovascular death by 33% (4 to 53, p = 0.027), coronary revascularization procedures by 38% (11 to 56, p = 0.009), and all-cause mortality by 24% (2 to 41, p = 0.037). The 5-year risk of fatal or nonfatal myocardial infarction, calculated using the predictors identified in the Cox analysis, ranged from <4.4% in the lowest quartile of risk to >9.6% in the highest quartile. The proportional benefit achieved by pravastatin was independent of other risk factors; hence, the absolute benefit of therapy was greatest in subjects with the highest baseline risk. Such subjects can be identified easily in the population and deserve high priority for treatment.