The multiple risk factor intervention trial in the U.S. A summary of results at four years in special intervention and usual care men.
Four-year results of the Multiple Risk Factor Intervention Trial indicate that an integrated approach to lifestyle modification of multiple risk factors is feasible and achieves significant lowering of risk factors compared with a group referred to usual medical care. The greatest changes and differences were in cigarette smoking. The hypertension treatment result met design predictions in the Special Intervention (SI) group. However, at 4 years the difference between groups was less than predicted, primarily due to unanticipated effectiveness of treatment of elevated pressures in the Usual Care (UC) group, reflecting recent secular changes in hypertension detection and control in the U.S. Similarly, the serum cholesterol net fall in the SI compared to UC group was 59% of goal, in part because of an unanticipated reduction in the UC group. The risk factor differences between groups were considerable, even though in some areas short of initial design expectations. The most serious consequence of a less than anticipated difference in risk characteristics between groups is an effective loss of power to detect significant differences in major disease endpoints. A further major benefit from the study has been the demonstration of the ability to have diverse scientific disciplines work effectively together in the long-term preventive management of healthy but high-risk men.