STRATEGIES FOR RECRUITMENT TO A POPULATION-BASED LUNG-CANCER PREVENTION TRIAL - THE CARET EXPERIENCE WITH HEAVY SMOKERS

The Beta-Carotene and Retinol Efficacy Trial tested the effect of the combination of beta-carotene (30 mg) and retinyl palmitate (25,000 uni ts) daily on the incidence of lung cancer in high-risk individuals. In study centers located in Seattle, WA; Portland, OR; and Irvine, CA, w e recruited current and recent ex-cigarette smokers, aged 50-69 years. Our primary method of recruitment was by mailing study information an d eligibility questionnaires to age-selected health insurance subscrib ers. A total of 1,216,549 subscriber households were contacted, which resulted in 16,449 enrollments and 12,184 randomizations. Other method s of recruitment yielded 1421 enrollments and 1002 randomizations. Sev enty-four % of those participants who enrolled in the 3-month placebo run-in were randomized. The major reasons for nonrandomization once su bjects were enrolled were: becoming ineligible (13%), concern about or development of side effects attributed to the study vitamins (18%), l oss of interest or being too busy (23%), and not showing up at the app ointed time or not willing to come to the study center (23%). Here, we discuss the reasons for nonparticipation and for subjects leaving the trial prior to randomization and possible modifications of trial desi gn and procedures to address these problems. This recruitment approach provided a constant flow of potentially eligible participants, screen ed out many ineligible and uninterested persons prior to the schedulin g of a study center visit, and ensured randomization of committed part icipants. A major limitation of this study was that the pool of minori ties that was reached was small.