Objective: To investigate the long-term effects of multifactorial primary prevention of cardiovascular diseases (CVD).
Design: The 5-year randomized, controlled trial was performed between 1974 and 1980. The subjects and their risk factors were reevaluated in 1985. Posttrial mortality follow-up was continued up to December 31, 1989.
Setting: Institute of Occupational Health, Helsinki, Finland, and Second Department of Medicine, University of Helsinki.
Participants: In all, 3490 business executives born during 1919 through 1934 participated in health checkups in the late 1960s. In 1974, 1222 of these men who were clinically healthy, but with CVD risk factors, were entered into the primary prevention trial; 612 were randomized to an intervention and 610 to a control group.
Interventions: During the 5-year trial, the subjects of the intervention group visited the investigators every fourth month. They were treated with intensive dietetic-hygienic measures and frequently with hypolipidemic (mainly clofibrate and/or probucol) and antihypertensive (mainly beta-blockers and/or diuretics) drugs. The control group was not treated by the investigators.
Main outcome measures: Total mortality, cardiac mortality, mortality due to other causes.
Results: Total coronary heart disease risk was reduced by 46% in the intervention group as compared with the control group at end-trial. During 5 posttrial years, the risk factor and medication differences were largely leveled off between the groups. Between 1974 and 1989 the total number of deaths was 67 in the intervention group and 46 in the control group (relative risk [RR], 1.45; 95% confidence interval [CI], 1.01 to 2.08; P = .048); there were 34 and 14 cardiac deaths (RR, 2.42; 95% CI, 1.31 to 4.46; P = .001), two and four deaths due to other CVD (not significant), 13 and 21 deaths due to cancer (RR, 0.62; 95% CI, 0.31 to 1.22; P = .15), and 13 and one deaths due to violence (RR, 13.0; 95% CI, 1.70 to 98.7; P = .002), respectively. Multiple logistic regression analysis of treatments in the intervention group did not explain the 15-year excess cardiac mortality.
Conclusion: These unexpected results may not question multifactorial prevention as such but do support the need for research on the selection and interaction(s) of methods used in the primary prevention of cardiovascular diseases.