METHODS: This systematic review used a broad search strategy to identify randomized controlled trials comparing interventions for increasing blood donations. After full-text review, 28 trials from 25 published articles were included. Sufficient data for meta-analysis were available from 27 trials. Monetary incentives were assumed to be equivalent regardless of value, and non-monetary incentives were assumed to be equivalent regardless of type. Non-incentive-based interventions identified included existing practice, letters, telephone calls, questionnaires, and the combination of a letter & telephone call. A network meta-analysis was used to pool the results from identified trials. A subgroup analysis was performed in populations of donors and non-donors as sensitivity analyses.
RESULTS: The best performing interventions were letter & telephone call and telephone call-only with odds ratios of 3·08 (95% CI: 1·99, 4·75) and 1·99 (95% CI: 1·47, 2·69) compared to existing practice, respectively. With considerable uncertainty around the pooled effect, we found no evidence that monetary incentives were effective at increasing donations compared to existing practice. Non-monetary incentives were only effective in the donor subgroup.
CONCLUSIONS: When pooling across modes of interventions, letter & telephone call and telephone call-only are effective at increasing blood donations. The effectiveness of incentives remains unclear with limited, disparate evidence identified.