Objective: To describe recruitment and enrollment experiences of 2 low back pain (LBP) randomized controlled trials (RCTs).
Design: Descriptive report.
Setting: Chiropractic research center in the midwest United States that is not a fee-for-service clinic.
Participants: Both trials enrolled participants with subacute or chronic LBP without neurologic signs who had not received spinal manipulative care during the previous month. For study 1 we screened 1940 potential participants to enroll 192 participants (89 women and 103 men), mean age 40.0 +/- 9.4 years (range, 21-54 years). For study 2 we screened 1849 potential participants to enroll 240 participants (105 women and 135 men) at least 55 years old (mean, 63.1 +/- 6.7 years).
Interventions: Study 1 randomly assigned participants to 2 weeks of 2 different chiropractic techniques or a wait list control group. Study 2 randomly assigned participants to 6 weeks of 2 different chiropractic techniques or medical care consisting of 3 provider visits for medications.
Outcome measures: Recruitment source costs and yield, and baseline characteristics of enrolled versus nonparticipants were recorded.
Results: We conducted 3789 telephone screens for both trials to enroll 432 (11%) participants, at a cost in excess of $156,000 for recruitment efforts. The cost per call for all callers averaged $41, ranging from $4 to $300 based on recruitment method; for enrolled participants, the cost per call was $361, ranging from $33 to $750. Direct mail efforts accounted for 62% of all callers, 57% for enrolled participants, and had the second lowest cost per call for recruitment efforts.
Conclusions: It is important that complementary and alternative medicine (CAM) research can be successfully conducted at CAM institutions. However, the costs associated with recruitment efforts for studies conducted at CAM institutions may be higher than expected and many self-identified participants are users of the CAM therapy. Therefore, strategies for efficient recruitment methods and targeting nonusers of CAM therapies should be developed early for CAM trials.