Participation and adherence among older men and women recruited to the Beta-Carotene and Retinol Efficacy trial (CARET).

We evaluated as functions of age and gender participation and adherence rates in older adults recruited to pilot studies for CARET, a multicenter chemoprevention trial. Eligible were men and women aged 50-69 who were current or recent former smokers, and men aged 45-74 with occupational exposure to asbestos. We found negligible differences by age in response to recruitment mailings, drop out during the enrollment process and after randomization, and adherence to taking the study capsules. Men had numerically lower drop-out and higher adherence rates than women, but differences were not statistically significant. These results should encourage researchers to recruit older men and women (at least up to age 69) to clinical trials.