INFLUENCE OF PRAVASTATIN AND PLASMA-LIPIDS ON CLINICAL EVENTS IN THE WEST OF SCOTLAND CORONARY PREVENTION STUDY (WOSCOPS)

Background-The West of Scotland Coronary Prevention Study was a primar y prevention trial that demonstrated the effectiveness of pravastatin (40 mg/d) in reducing morbidity and mortality from coronary heart dise ase (CHD) in moderately hypercholesterolemic men. The present analysis examines the extent to which differences in LDL and other plasma lipi ds both at baseline and on treatment influenced CHD risk reduction. Me thods and Results-Relationships between baseline lipid concentrations and incidence of all cardiovascular events and between on-treatment li pid concentrations and risk reduction in patients taking pravastatin w ere examined by use of Cox regression models and by division of the co hort into quintiles, Variation in plasma lipids at baseline did not in fluence the relative risk reduction generated by pravastatin therapy. Fall in LDL level in the pravastatin-treated group did not correlate w ith CHD risk reduction in multivariate regression. Furthermore, maximu m benefit of an approximate to 45% risk reduction was observed in the middle quintile of LDL reduction (mean 24% fall); further mean decreme nts in LDL (up to 39%) were not associated with a greater decrease in CHD risk. Comparison of event rates between placebo-and pravastatin-tr eated subjects with the same LDL cholesterol level provided evidence f or an apparent treatment effect that was Independent of LDL. Conclusio ns-We conclude that the treatment effect of 40 mg/d of pravastatin is proportionally the same regardless of baseline lipid phenotype. Then i s no CHD risk reduction unless LDL levels are reduced, but a fall in t he range of 24% is sufficient to produce the full benefit in patients taking this dose of pravastatin. LDL reduction alone does not appear t o account entirely for the benefits of pravastatin therapy.