IMPACT OF CHOLESTEROL REDUCTION ON PERIPHERAL ARTERIAL-DISEASE IN THEPROGRAM ON THE SURGICAL CONTROL OF THE HYPERLIPIDEMIAS (POSCH)

Background. Few lipid/atherosclerosis intervention trials have assesse d the impact of cholesterol reduction on peripheral arterial disease. The 838 patients evaluated in the Program on the Surgical Control of t he Hyperlipidemias (POSCH) trial represent more than the total number of patients in the seven previously reported studies. Methods. Periphe ral arterial disease in POSCH was assessed by progression of clinical disease, serial changes in the systolic blood pressure ankle/brachial index (ABI), and changes on sequential peripheral arteriograms. Result s. At the time of formal closure of the POSCH trial on July, 19, 1990, claudication or limb-threatening ischemia was exhibited in 72 of 417 control group (CG) patients and in 54 of 421 intervention group (IG) p atients (IG relative risk [RR] 0.702, 95% confidence interval [CI] 0.1 69 to 1.000, p = 0.049). With additional follow-up evaluation to Septe mber 30, 1994, clinical peripheral arterial disease was evident in 91 CG patients and 64 IG patients (RR 0.656, 95% CI 0.200 to 0.903, P = 0 .009). At the 5-year follow-up evaluation, an ABI of less than 0.95 wa s present in 41 of 120 CG patients and in 24 of 126 IG patients, all o f whom had an ABI of 0.95 or greater at baseline (RR in the IG of 0.55 7, CI 0.360 to 0.863, p < 0.01). No appreciable differences were noted in the progression or regression of arteriographic peripheral arteria l disease between the two groups. Conclusions. Effective cholesterol r eduction in POSCH led to statistically significant differences between the control and the intervention groups in the development of clinica lly evident peripheral arterial disease and in the ABI values, but not in the peripheral arteriograms. Additional studies need to assess the correlation between peripheral arterial changes and coronary arterial changes and clinical atherosclerosis events. Intervention trials that study peripheral arterial disease have intrinsic value in the evaluat ion of the impact of risk factor modification on progression of athero sclerotic peripheral arterial disease.