Partial Ileal Bypass — Results of the Program on the Surgical Control of the Hyperlipidemias (POSCH)

Abstract

The Program on the Surgical Control of the Hyperlipidemias (POSCH) was a prospective, randomized, secondary, atherosclerosis intervention trial designed to examine the effects of lipid lowering by the partial ileal bypass (PIB) operation on overall and coronary heart disease morbidity and mortality. POSCH enrolled 838 hypercholesterolemic survivors of a single myocardial infarction (417 randomized to a diet-treated control group and 421 randomized to a diet plus PIB-treated surgery group) with a mean follow-up of 9.7 years. Compared to the control group, the surgery group had a 23.3% lower total plasma cholesterol level, a 37.7% lower low density lipoprotein (LDL) cholesterol level, and a 4.3% higher high density lipoprotein (HDL) cholesterol level at five-year follow-up. Overall and coronary heart disease mortality were reduced, but these reductions did not achieve statistical significance. In patients with a left ventricular ejection fraction ≥ 50%, overall mortality was 36% lower in the surgery group (p=0.021). The occurrence of the combined endpoint of coronary heart disease death or confirmed nonfatal myocardial infarction was reduced by 35% (p<0.0001). Comparison of baseline coronary arteriograms with studies performed 3, 5, 7, or 10 years after randomization consistently demonstrated decreased coronary artery disease progression and increased coronary artery disease regression in the surgery group. The principal side effects of partial ileal bypass included diarrhea, kidney stones, gallstones, and intestinal obstruction. The POSCH trial results clearly demonstrate the beneficial effects of aggressive, non-pharmacologic lipid lowering and carefully document the long-term results of partial ileal bypass in hypercholesterolemic patients with atherosclerosis.