Mailing strategies and costs of recruiting heavy smokers in CARET, a large chemoprevention trial

Recruitment costs represent a major portion of the budget for large clinical trials during the initial years of the study. Further, the rate of recruitment affects allocation of resources in future years. To learn about the costs and yields of recruiting from different populations and under different mailing strategies, we monitored recruitment yields of eligible heavy smokers for the Carotene and Retinol Efficacy Trial (CARET) at the Portland Study Center. Yields from the mailings, measured by response rate, percent of potential participants randomized, and related costs per randomization varied both by mailing strategy and by population targeted. Yield and cost varied significantly across population sources. Less variation was observed among various mailing strategies. Tracking the recruitment process yield provided useful information that allowed us to adjust recruitment approaches and achieve our randomization goals quickly and economically. (C) Elsevier Science Inc. 1998.