Recruitment experience in the Aspirin Myocardial Infarction Study.

The Aspirin Myocardial Infarction Study (AMIS) was a randomized double-masked trial of the efficacy of aspirin in the secondary prevention of coronary heart disease. Thirty clinics randomized 4524 post-myocardial infarction patients to aspirin or placebo treatment. Recruitment was achieved in 14 months as planned, but nearly half of the patients were not randomized until the last 5 months of the recruitment period. Direct public appeal, self-referral, and review of hospital records provided 75% of the participants. Physician referral accounted for only 15%. The demographic characteristics of the sample revealed two thirds to be 50 years of age or older, 90% to be male, and 90% to be white.