MR FIT

The Multiple Risk Factor Intervention Trial (MR FIT) study was a massive, lengthy, expensive clinical trial initiated in 1972 that was designed to demonstrate the value of special interventions to reduce health risks from smoking, high blood pressure and elevated cholesterol levels. The study particularly examined the extent to which intervention could affect death rates from coronary disease.

MR FIT was carried out by the National Heart, Lung and Blood Institute and the National Institutes of Health and was a very large study for its time. MR FIT was a product of more than seven years, 28 institutions and 250 investigators. Approximately 13,000 middle-aged males at high risk for heart disease were enrolled in the study. Of those, about 6,500 received "special interventions" which included modification of their diets, anti-hypertension treatment, and/or counseling for smoking cessation. Another group of 6,500 middle-aged white makes were assigned to the "usual care" group. That is, the level of care or intervention they received was largely dependent on the quality of care in their own individual communiities. Each of these volunteers was followed for a minimum of six years.

The theory was that the "Usual Care'' group would serve as an appropriate control group, showing higher mortality than the "Special Intervention" group, but that is not what happened. Instead, both groups experienced substantially lower mortality than anticipated, which reduced the statistical power of the comparison.

The results flew in the face of medical dogma. It was thought that the results may have been affected by up to five factors:

1. Identifying patients as high risk and informing them of it. 2. Notifying study physicians that their patients were in a high-risk control group. 3. Providing original and annual data to the physicians. 4. The quality of practice of the personal physicians of the "Usual Care" group. 5. The increased knowledge and behavior change that much of the public at large was experiencing in this arena during the project time.