THE EFFECT OF PROBUCOL ON FEMORAL ATHEROSCLEROSIS - THE PROBUCOL QUANTITATIVE REGRESSION SWEDISH TRIAL (PQRST)

The Probucol Quantitative Regression Swedish Trial tested whether trea tment of hypercholesterolemic persons with probucol for 3 years affect ed femoral atherosclerosis. The primary end point was the change in at heroma volume estimated as change in lumen volume of the femoral arter y assessed by quantitative arteriography. Three hundred three patients with visible atherosclerosis were randomized to probucol 0.5 g twice daily, or to placebo. All patients were given diet and cholestyramine, 8 to 16 g/day. Twenty-nine patients were excluded because of inadequa te primary end point measurements. The mean age of the remaining 274 s ubjects (158 were men) was 55 years. Seventeen percent had intermitten t claudication and 24% bad angina pectoris. After 3 years, the probuco l-treated patients had 17% lower serum cholesterol, 12% lower low-dens ity lipoprotein cholesterol, 24% lower total high-density lipoprotein cholesterol, and 34% tower high-density lipoprotein(2) cholesterol lev els than control subjects. All lipoprotein differences between the tre atment groups remained highly significant during the trial. There was no statistically significant change in lumen volume between the probuc ol and the control group. Furthermore, there was no difference between the treatment groups with regard to change in arterial edge roughness or amount of aorto-femoral atherosclerosis; neither were there any di fferences between the treatment groups with regard to change in ST-seg ment depressions on exercise tests or ankle/arm blood pressure (second ary end points). In the control group, lumen volume increased (p <0.00 1) and roughness of the femoral artery decreased (p <0.05). It is conc luded that the addition of probucol to diet and cholestyramine did not result in any significant regression of atherosclerosis compared with that found in patients treated only with diet and cholestyramine. How ever, in this control group there was statistically significant eviden ce of improvement.