Program on Surgical Control of Hyperlipidemias (POSCH)
Year Begun: 1975
Location: University of Minnesota
Principal Investigator: Buchwald, Henry
The POSCH study asked whether partial ileal bypass and the resulting reduction in cholesterol levels would translate in lower total mortality and mortality due to coronary heart disease.
The study included 838 survivors of a single myocardial infarction, with 417 participants in the control group and 421 in the surgery group. The control group received diet instruction and the surgery group received diet instruction and surgery. The first five years included annual visits where lipid analysis was performed. Later follow-ups for coronary and peripheral arteriograms occurred at 3 and 5 years and either at 7 or 10 years, with an average follow-up of 9.7 years and a high of 14.8 years. The study population included women and men, but men dominated the study (90.7%).
At five years there was a 23.3% lower plasma cholesterol level in the surgery group compared to the control group. Death due to coronary heart disease and confirmed nonfatal myocardial infarction was 35% lower for the surgery group and was maintained at the five-year follow-up. Arteriograms and electrocardiograms showed an increase in disease progression over the follow-up period, but was consistently higher for the control group than for the surgery group.
The POSCH study demonstrated that partial ileal bypass produces sustained improvement in blood lipid levels and reduces morbidity due to coronary heart disease. This study confirmed, in a randomized controlled clinical trial of “obligate” choleserol lowering by surgery, the hypothesis that lowering total plasma cholesterol level would lead to a reduction in the progression of atherosclerosis. The completion of the trial coincided with the first results of trials of statins, which eventuated in even greater lipoprotein (LDL) lowering and comparably reduced risk, without the cost and risks of intestinal surgery. (FB/HB)
Program on the Surgical Control of the Hyperlipidemias, “Effect of Partial Ileal Bypass Surgery on Mortality and Morbidity From Coronary Heart Disease in Patients with Hypercholesterolemia.” (1990) The New England Journal of Medicine. 323(14): 946-955.
Buchwald, H., Boen, J.R., Nguyen, P.A., Williams, S.E., Matts, J.P. “Plasma Lipids and Cardiovascular Risk: a POSCH Report.” (2001) Atherosclerosis. 154: 221-227.