Recruitment experience in the African American Study of Kidney Disease and Hypertension (AASK) Pilot Study.

Several approaches for recruitment of African American adults with renal insufficiency due to hypertension (glomerular filtration rate between 25 and 70 ml/min/1.73 m2) were explored in the Pilot Study for the African American Study of Kidney Disease and Hypertension (AASK). Over a period of 42 weeks, prescreening information was obtained on 2880 individuals, of whom 498 (17%) were evaluated at a screening visit. Two hundred and twenty-five (8%) had an 125I-iothalamate assessment of glomerular filtration rate. Ninety-four of 97 participants who met all the study eligibility criteria were enrolled in the trial. The most common reasons for ineligibility during screening were absence of renal insufficiency or hypertension, presence of diabetes mellitus, and a body mass index above the acceptable level. Overall, an average of 31 prescreen contacts and 8 screening visits were conducted for every randomization (3.3% yield from prescreening to randomization). Screening in clinical practice was the most efficient method for recruitment (12.6% yield from prescreen contact to randomization compared to 1.1% from mass mailing campaigns, 1.3% from mass media campaigns, and 1.7% from referrals by patients with end-stage renal disease). Randomization yields increased with progressively higher age ranges (2.4%, 3.3%, and 6.0% prescreen to randomization yields for those aged < or = 50, 51-60, and 61-70, respectively). A slight majority (51%) of the prescreen contacts were women, but 75% of the randomized participants were men. Our results suggest that clinic-based screening is an effective approach for recruitment of African Americans with hypertension and renal insufficiency into clinical trials. They also suggest that enrollment of African American women in such studies is a special challenge.