Recruitment for phase I of the trials of hypertension prevention.

Phase I of the Trials of Hypertension Prevention was a multicenter, randomized, controlled trial designed to determine the efficacy of seven nonpharmacologic interventions in reducing blood pressure among persons with high-normal diastolic blood pressure. The initial goal for recruitment was to enroll 2,100 participants over a nine-month period. The two major strategies for reaching potential participants were direct mailings and work site screenings. The yield from the first screening visit to randomization was 13% overall, with clinic-specific yields ranging from 4.5% to 31.7%. After five months of recruitment, approximately 60% of the goal for that point in the recruitment timetable had been randomized. Clinical centers falling short of their goals at that time altered their recruitment strategies and intensified their efforts, and centers that had exceeded their goals recruited additional participants. As a result, 2,182 participants, or 104% of the goal for recruitment, were randomized over a 13-month period. Those clinics using a cohort, or wave, type of enrollment were most successful in achieving their recruitment goals within the prescribed timetable.