Three of the CDP treatments (two doses of estrogen and dextrothyroxine) were stopped prematurely because of toxicity. At the time the treatments were stopped, it was thought that future assessment of the status of patients on those treatments would be important to evaluate long-term sequellae. Another clinical trial evaluating clofibrate for primary prevention found that more patients on that treatment than on placebo had died. This effect persisted even after the treatment was stopped. Therefore, it was considered necessary to follow the CDP patients on clofibrate.