WHO cooperative trial on primary prevention of ischaemic heart disease with clofibrate to lower serum cholesterol: final mortality follow-up. Report of the Committee of Principal Investigators.

This is the final report on mortality amongst men in the WHO cooperative trial of the prevention of ischaemic heart disease (IHD) by clofibrate and it takes the follow-up a further 4 years to the end of 1982. Mean observation was 13.2 years, 5.3 in the trial and 7.9 afterwards. 1788 deaths were recorded in 208 000 man-years. In the 877 new deaths reported here, there was an excess of 9 deaths in the high cholesterol control group compared with the clofibrate-treated group. In the whole period there were 70 (11%) more deaths in the clofibrate-treated group. Excess mortality in the clofibrate-treated group was much greater during the "treatment period" (there was an excess of 47% during treatment compared with 5% after treatment had ended) and was due to a wide variety of causes other than IHD. Thus, the excess mortality in the clofibrate-treated group has not continued after the end of treatment. The substantial excess previously reported remains unexplained.