Blood Donation and Monetary Incentives: A Meta-Analysis of Cost-Effectiveness

The effectiveness of monetary incentives to increase altruistic behavior is in dispute. Paying blood donors might be ineffective, as it could decrease altruistic motivations of voluntary donors (motivational crowding-out) or decrease blood quality (increase transmittable infectious disease risks). In a meta-analysis, including observational studies, natural experiments and field experiments, the cost-effectiveness of monetary incentives (cash payments and quasi-cash material rewards) for blood donation is estimated. The search strategy identified 17 studies as eligible. After screening for relevance and quality, 8 studies were retained and GRADE-rated for quality of evidence, offering 12 estimates of the marginal donation rate. The combined, random-effects estimate of the marginal donation rate of monetary incentives is 0,4 extra blood units collected per 1000 inhabitants per year per dollar incentive, but with large variation due to large heterogeneity of the studies (explained by different contexts and differences in perceived costs for donors). A higher estimate of 1,0 extra blood units per 1000 inhabitants per year per dollar incentive, is obtained with a restricted meta-analysis that only includes the most reliable and more homogeneous studies. With donor payments, it costs an additional $22 to $121 to increase the blood supply with one unit of whole blood, but this strongly varies with context and local conditions. The positive marginal donation rate of donor payments is inconsistent with a crowding-out effect (a reduction in total blood supply caused by a decrease in altruistic motivations when donors are paid), at least in the short-run. The available studies are not suitable to estimate possible long-term crowding-out effects, negative spillover effects (eg, a decrease in other prosocial behavior or altruistic norms) or transmittable infectious disease risks. Whether monetary incentives are the most cost-effective and ethical strategy to increase blood and plasma supply, remains an open question.