A comparative analysis of recruitment methods used in a randomized trial of diabetes education interventions

Recruitment methods heavily impact budget and outcomes in clinical trials. We conducted a post-hoc examination of the efficiency and cost of three different recruitment methods used in Journey for Control of Diabetes: the IDEA Study, a randomized controlled trial evaluating outcomes of group and individual diabetes education in New Mexico and Minnesota. Electronic databases were used to identify health plan members with diabetes and then one of the following three methods was used to recruit study participants: 1. Minnesota Method 1--Mail only (first half of recruitment period). Mailed invitations with return-response forms. 2. Minnesota Method 2--Mail and selective phone calls (second half of recruitment period). Mailed invitations with return-response forms and subsequent phone calls to nonresponders. 3. New Mexico Method 3--Mail and non-selective phone calls (full recruitment period): Mailed invitations with subsequent phone calls to all. The combined methods succeeded in meeting the recruitment goal of 623 subjects. There were 147 subjects recruited using Minnesota's Method 1, 190 using Minnesota's Method 2, and 286 using New Mexico's Method 3. Efficiency rates (percentage of invited patients who enrolled) were 4.2% for Method 1, 8.4% for Method 2, and 7.9% for Method 3. Calculated costs per enrolled subject were $71.58 (Method 1), $85.47 (Method 2), and $92.09 (Method 3). A mail-only method to assess study interest was relatively inexpensive but not efficient enough to sustain recruitment targets. Phone call follow-up after mailed invitations added to recruitment efficiency. Use of return-response forms with selective phone follow-up to non-responders was cost effective.