Program on the Surgical Control of the Hyperlipidemias

Abstract

The Program on the Surgical Control of the Hyperlipidemias (POSCH), a randomized clinical trial, tested the hypothesis that cholesterol modification induced by partial ileal bypass would favorably affect mortality and morbidity due to coronary heart disease (CHD). The study population consisted of 838 patients (417 in the control group and 421 in the surgery group) in four clinical centers, both men (90.7%) and women with an average age of 51 years who had survived a first myocardial infarction. The lipid changes in POSCH have been the most marked in any atherosclerosis intervention trial utilizing a single mode of intervention in addition to diet therapy. At 5 years, the surgery group, compared with the control group, had a 23.3 +/- 1.0% (mean +/- SE) lower total plasma cholesterol level (p < 0.0001), a 37.7 +/- 1.2% lower low-density lipoprotein cholesterol level (p < 0.0001), and a 4.3 +/- 1.8% higher high-density lipoprotein cholesterol level (p = 0.02). For the combined end point of CHD mortality and confirmed nonfatal myocardial infarction, there was a 35.0% reduction in the surgery group (p < 0.001). Coronary artery bypass grafting was reduced in the surgery group by 62.0% (p < 0.0001) and percutaneous transluminal coronary angioplasty was reduced by 55.0% (p < 0.01). A comparison of baseline coronary arteriograms with those obtained at 3, 5, 7, and 10 years consistently showed less atherosclerosis disease progression (p < 0.001) and greater atherosclerosis disease regression at 5 and 7 years (p < 0.01) in the surgery group. At formal trial completion in July 1990, the overall mortality in the surgery subgroup with an ejection fraction of 50% or greater was 36.1% lower (p = 0.02). During subsequent follow-up, trends toward statistical significance for differences in both CHD and in overall mortality have become evident. The POSCH results provide strong support for beneficial clinical and arteriographic reduction of atherosclerosis progression after lipid modification by partial ileal bypass.