Recruitment of older adults for a randomized, controlled trial of exercise advice in a general practice setting

OBJECTIVES: The success of any clinical trial depends strongly on recruiting enough participants in a reasonable time period. This paper aims to identify the obstacles, as well as the successful aspects, of recruiting of older participants into an exercise study. DESIGN: This describes the recruitment of 299 older adults into a randomized, controlled trial of exercise advice in a general practice setting. Letters of invitation were sent from two general practices inviting the patients to attend a 15-minute screening appointment. Patients considered eligible for enrollment were then scheduled for a baseline appointment and randomized into the trial. SETTING: Two general practices in Adelaide, South Australia. PARTICIPANTS: Healthy, sedentary, community-dwelling patients aged 60 years or older. RESULTS: A total of 2878 letters of invitation were sent, and 913 patients attended a screening appointment. Of these, 351 (38.4%) were initially eligible, with one-third excluded because they were already too physically active. Two hundred ninety-nine participants, approximately 1 of every 10 patients sent letters, were enrolled in the project at the end of a 15-week period. DISCUSSION: A general practice approach was effective in recruiting 299 older adults to an exercise project within an acceptable time frame. Factors promoting the success of recruitment through general practice included choosing large, well established practices, computerized age-sex registers, and placing minimal demands on the general practitioners and practice staff. A continuing problem with recruiting participants for a project involving exercise is that the volunteer population tends to be healthy and interested in physical activity.