Pravastatin And Coronary Heart Disease - Response

To the Editor: In the April 21, 1998, edition of Circulation , the WOSCOPS study group (West of Scotland Coronary Prevention Study) report that the benefit achieved by administration of pravastatin in WOSCOPS was essentially independent of the percentage by which LDL cholesterol was lowered by treatment and greater than that which could be attributed to lowering of LDL cholesterol alone.1 With unexpected findings of this nature, it is important to exclude bias, especially when the results are derived from post hoc subgroup analysis. In the case at hand, a potential source of bias lies in the selection procedure. WOSCOPS included only men with an LDL cholesterol level of 174 to 232 mg/dL. However, individuals with a history of severe illness, ECG abnormalities or arrhythmias, or severe arterial hypertension, some of which are statistically associated with raised LDL cholesterol levels, were excluded.2 This may have led to a gradient of non–LDL-related risk of coronary heart disease (CHD), ie, men at the high …