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In the early 1970’s several controlled multifactorial prevention trials were launched that used a wide variety of methods and intervention techniques. Both the Multiple Risk Factor Intervention Trial (1), in the United States, and the Oslo Study (2) were aimed at modifying the coronary risk profile in high-risk men by means of face-to-face counseling. The Goteborg Study (3) involved the random allocation of 10,000 subjects into an intervention group and 20,000 subjects into two control groups; both face-to-face advice and group dynamics were used in the intervention group with the cooperation of specialised clinics. All the above mentioned studies were based on individual randomization. A controlled, non randomized, multifactorial study was conducted in North Karelia (Finland), a neighbouring province was used as control (4). Counseling was mainly provided through mass media.

The Multiple Risk Factor Intervention Trial was initiated by the National Heart, Lung and Blood Institute in 1971, in accordance with recommendations made earlier that year by a task force on atherosclerosis (Hew, 1971). It is a randomized, nondouble blind clinical trial of the efficacy of modifying multiple risk factors (elevated blood lipid levels, hypertension, and cigarette smoking) for the reduction of coronary heart disease mortality. The first eight participating clinical centers were selected in June of 1972, followed by the addition of 12 others during the next 18 months. Also established in 1972 were a coordinating center at the University of Minnesota, a central laboratory at the Pacific Medical Center in San Francisco, and electrocardiography centers at the University of Minnesoty and Dalhousie University in Halifax, Nova Scotia.

In 1972, when the Multiple Risk Factor Intervention Trial (MRFIT) was being organized, the only prospective epidemiological evidence linking the Type A behavior pattern to increased risk of coronary heart disease (CHD) came from the Western Collaborative Group Study (WCGS), which found that men characterized as Type A by means of a structured interview had twice the risk of CHD in comparison to those characterized as Type B, and that this higher level of risk persisted after adjustment for age, blood pressure, cigarette smoking, and serum cholesterol level (Rosenman et al. 1964,1975,1976).

The scientific background of the Multiple Risk Factor Intervention Trial (MRFIT) was the extensive set of data from all branches of medical research (clinical and pathologic investigation, epidemiology, animal experimentation) demonstrating a relationship between life-styles (particularly eating and smoking habits), life-style-related risk factors, and the occurrence of epidemic premature coronary heart disease (CHD) in Western industrialized countries. As repeatedly noted, these data indicate the possibility of CHD prevention by improving life-styles and controlling established major risk factors. Table 1 presents representative epidemiologic data on the impact on risk of first major events of coronary heart disease of the three major established risk factors, serum cholesterol, blood pressure, and cigarette use [1].

I have had the opportunity over the past thirteen years to participate in the discussions, proposals, plans and execution of one large multiple risk factor trial intended to contribute to our knowledge of the control and prevention of coronary heart disease. The subject at the time of our earliest consideration seemed complex. With the passage of years with experience, there has been ample confirmation of this initial impression. Now as I discuss this with you, I realize that such an investigative undertaking is indeed complicated and there are many opportunities for incorrect assumptions and inadequate execution and less than optimal interpretation of the results. Perhaps it is admirable, or some might say, less charitably, astonishing, that anyone would want to undertake one. Nonetheless, I have found that the pleasures and the satisfactions and the excitement and the yield in terms of knowledge have greatly outweighed the pains and concerns.