The randomized controlled trial (RCT) is the most definitive tool for evaluating an intervention. However, methodological deficiencies may limit the internal or external validity of the RCT.
Our aim was to describe the tactics used and the resources required randomly to select and recruit family physicians (FPs) and their patients aged 65 and older (seniors) for a community-based cluster RCT in primary care.
We randomly selected 48 FPs in 24 urban and rural sites in Southern Ontario, and 889 of their community-dwelling seniors (approximately 20 per FP) taking five or more medications daily. To accomplish this, the principal investigator (an FP) contacted the eligible FPs. The participating FPs' office staff then generated and contacted the roster of eligible seniors, with support provided by the research staff.
Of the 163 randomly selected FPs telephoned, 94 were ineligible and 48 (69.6%) of the remaining 69 participated. The rosters were generated with the assistance of the research staff (taking 1.5-8.0 hours) in each of the 48 practices, using electronic appointment records (n = 26), electronic billing records (n = 17), electronic medical records (n = 2) or written charts or file cards (n = 3). Of the 2078 seniors approached, 799 were ineligible and 889 (69.5%) of the remaining 1279 participated. Seniors' refusal rates among practices ranged from 4.8 to 62.3%.
Recruitment of a representative sample and generalizability of results are possible in RCTs in primary care. Involvement of an FP in physician recruitment and clinical research nurses who provided assistance to office staff were keys to success.