BACKGROUND:

The Multiple Risk Factor Intervention Trial was a randomized primary prevention trial to test the effect of a multifactor intervention program on mortality from coronary heart disease in 12,866 high-risk men aged 35 to 57. The primary screening for MRFIT began in November 1973 and continued through November 1, 1975. The primary screening was conducted at clinical center sites, central neighborhood locations, and places of employment.

Information was collected on smoking history, blood pressure, serum cholesterol, birthdate, race, and social security number as well as previous hospitalization for a heart attack and use of medication for diabetes. Systolic and diastolic blood pressures were measured and blood drawn for serum cholesterol determinations. The results of the screening examination were transmitted to the Coordinating Center.

DESIGN NARRATIVE:

Using data supplied by the Social Security Administration, the vital status of the MRFIT screenees was determined. A screenee was identified as deceased if the social security number and first two letters of the last name, as recorded on the MRFIT screening form, matched a record on the Social Security Administration master death file. The state health department was contacted to obtain the death certificate which was then coded for the underlying cause of death according to the International Classification of Diseases, 9th Revision. Because the Social Security Adminstration master death file was not completely accurate, the National Death Index was also used. Studies were conducted on the relationships of isolated systolic hypertension to stroke and coronary heart disease mortality, and on seasonal and regional variations in cardiovascular mortality. Using data from the Census Bureau (education and income levels by zip code), the socio-economic status of participants was indirectly estimated and the coronary heart disease and cancer death rate differences between white and Black men were evaluated by social class. Studies were also conducted on the associations of cause- specific cancer mortality and serum cholesterol concentration, and on the association of serum cholesterol, diastolic blood pressure, and cigarettes smoked per day with mortality from coronary heart disease and cerebrovascular disease for Black and white men.