Cost-effectiveness of health research study participant recruitment strategies: a systematic review

A large fraction of the cost of conducting clinical trials is allocated to recruitment of participants. A synthesis of findings from studies that evaluate the cost and effectiveness of different recruitment strategies will inform investigators in designing cost-efficient clinical trials.

To systematically identify, assess, and synthesize evidence from published comparisons of the cost and yield of strategies for recruitment of participants to health research studies.

We included randomized studies in which two or more strategies for recruitment of participants had been compared. We focused our economic evaluation on studies that randomized participants to different recruitment strategies.

We identified 10 randomized studies that compared recruitment strategies, including monetary incentives (cash or prize), direct contact (letters or telephone call), and medical referral strategies. Only two of the 10 studies compared strategies for recruiting participants to clinical trials. We found that allocating additional resources to recruit participants using monetary incentives or direct contact yielded between 4% and 23% additional participants compared to using neither strategy. For medical referral, recruitment of prostate cancer patients by nurses was cost-saving compared to recruitment by consultant urologists. For all underlying study designs, monetary incentives cost more than direct contact with potential participants, with a median incremental cost per recruitment ratio of Int$72 (Int$-International dollar, a theoretical unit of currency) for monetary incentive strategy compared to Int$28 for direct contact strategy. Only monetary incentives and source of referral were evaluated for recruiting participants into clinical trials.

We did not review studies that presented non-monetary cost or lost opportunity cost. We did not adjust for the number of study recruitment sites or the study duration in our economic evaluation analysis.

Systematic and explicit reporting of cost and effectiveness of recruitment strategies from randomized comparisons is required to aid investigators to select cost-efficient strategies for recruiting participants to health research studies including clinical trials.