Retention of first-time blood donors is a major challenge for blood supply sustainability, as many do not return after their initial donation. Barriers include fear of adverse events, lack of confidence and uncertainty about the impact of their donation. Active contact interventions, such as personalized messages or phone calls, have been proposed to improve donor engagement and encourage repeat donations, but their effectiveness remains uncertain across different settings and intervention types.

To evaluate the effectiveness of active contact strategies compared to no contact in increasing return donation rates among first-time blood donors.

A systematic review and meta-analysis were conducted following PRISMA guidelines. Eligibility criteria included randomized controlled trials (RCTs) enrolling first-time blood donors, comparing any active contact intervention (e.g., SMS, telephone, letters) versus no contact, reporting return rates for subsequent donations. Study selection and data extraction were performed independently in duplicate. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Searches were performed in PubMed, Embase, and the Cochrane Library up to February 2025. Meta-analyses were conducted in R software (v.4.3.3) using fixed- or random-effects models based on heterogeneity (I²). Effect sizes were expressed as risk ratios (RRs) with 95% confidence intervals (CIs). Funnel plots assessed publication bias, and leave-one-out sensitivity analyses were performed. The protocol was registered in PROSPERO (CRD420251085364).

Seven RCTs including 11,029 first-time donors were analyzed. Active contact strategies significantly increased return donation rates compared to no contact (RR = 1.25; 95% CI: 1.18–1.31; I² = 0%). Subgroup analyses demonstrated significant effects for SMS (RR = 1.26; 95% CI: 1.17–1.35; I² = 37,8%) and telephone calls (RR = 1.25; 95% CI: 1.15–1.36; I² = 0%). When categorized by content, emotional messages (RR = 1.27; 95% CI: 1.18–1.36) and reminders (RR = 1.25; 95% CI: 1.14–1.37) were effective, while educational messages had inconclusive effects (RR = 1.10; 95% CI: 0.95–1.27). In analyses by timing, both short-term interventions (≤ 2 months) (RR = 1.23; 95% CI: 1.13–1.34; I² = 18%) and long-term interventions (> 2 months) (RR = 1.26; 95% CI: 1.15–1.38; I² = 0%) significantly increased donor return. Leave-one-out sensitivity analyses confirmed stability of findings, with RR values ranging from 1.23 to 1.27. Funnel plots indicated minimal publication bias. Active contact strategies, particularly SMS and telephone calls, consistently enhance donor return rates among first-time blood donors. Although the overall meta-analysis showed no heterogeneity, the moderate heterogeneity observed in SMS interventions (I² = 37.8%) suggests that factors such as content, personalization, and timing may influence effectiveness. These interventions represent practical, scalable, and low-cost tools for donor retention programs, supporting their broader implementation and highlighting the need for further research to optimize their impact.