DISCONTINUATION OF ANTIHYPERLIPIDEMIC DRUGS - DO RATES REPORTED IN CLINICAL-TRIALS REFLECT RATES IN PRIMARY-CARE SETTINGS

Background. Discontinuation rates for drugs used to treat chronic cond itions may affect the success of therapy. However, the discontinuation rates reported in clinical trials may not reflect those in primary ca re settings. Methods. We conducted a cohort study using computerized r esearch files and medical records on 2369 new users of antihyperlipide mic therapy at two health maintenance organizations (HMOs) from 1988 t hrough 1990. The rates of drug discontinuation in these primary care s ettings were compared with the rates reported in clinical trials publi shed from 1975 through 1993, located with the Medline data base. Resul ts. In the HMOs, the one-year probability of drug discontinuation was 41 percent for bile acid sequestrants (95 percent confidence interval, 38 to 44 percent), 46 percent for niacin (95 percent confidence inter val, 42 to 51 percent), 15 percent for lovastatin (95 percent confiden ce interval, 11 to 19 percent), and 37 percent for gemfibrozil (95 per cent confidence interval, 31 to 43 percent), For the bile acid sequest rants, niacin, and gemfibrozil, the risks of discontinuation were subs tantially higher in the HMOs than in randomized clinical trials, in wh ich the summary estimates of this risk were 31 percent, 4 percent, and 15 percent, respectively, for trials of one year or longer, The rates of discontinuation in open-label studies were similar to those in the HMOs. Conclusions. The discontinuation rates reported in randomized c linical trials may not reflect the rates actually observed in primary care settings, The effectiveness and tolerability of antihyperlipidemi c medications should be Studied further in populations that typically use the agents.