The Cholesterol-Lowering Atherosclerosis Study (CLAS) was a randomized, placebo-controlled, angiographic trial testing combined colestipol hydrochloride and niacin therapy in 162 nonsmoking men aged 40 to 59 years with previous coronary bypass surgery. During two years of treatment there was a 26% reduction in total plasma cholesterol, a 43% reduction in low-density lipoprotein cholesterol, plus a simultaneous 37% elevation of high-density lipoprotein cholesterol. This resulted in a significant reduction in the average number of lesions per subject that progressed (P<.03) and the percentage of subjects with new atheroma formation (P<.03) in native coronary arteries. Also, the percentage of subjects with new lesions (P<.04) or any adverse change in bypass grafts (P<.03) was significantly reduced. Deterioration in overall coronary status was significantly less in drug-treated subjects than placebo-treated subjects (P<.001). Atherosclerosis regression, as indicated by perceptible improvement in overall coronary status, occurred in 16.2% of colestipol-niacin treated vs 2.4% placebo treated (P =.002).
Blankenhorn DH, Nessim SA, Johnson RL, Sanmarco ME, Azen SP, Cashin-Hemphill L. Beneficial Effects of Combined Colestipol-Niacin Therapy on Coronary Atherosclerosis and Coronary Venous Bypass Grafts. JAMA. 1987;257(23):3233-3240. doi:10.1001/jama.1987.03390230069027