Abstract
BACKGROUND: Social media platforms have shown considerable potential in shaping behaviors and have become a central component of public health and organizational outreach efforts. Blood collection agencies increasingly rely on social media not only for donor recruitment and retention but also for promoting donation-related behaviors. Regular, day-to-day status updates form a significant part of the communication strategies implemented by blood banks. OBJECTIVE: Despite social media's promise as a tool for behavior change, evidence supporting the persuasive effects of routine day-to-day status updates remains limited-not only within the context of blood donation but also across broader health domains. To address this gap, we examine long-term attitudinal and behavioral outcomes to understand better the impact of an organization's social media efforts on health-related behaviors. METHODS: We conducted a randomized controlled field trial to investigate the effects of a blood bank's Facebook page on donation attitudes and behavior. All newly registered blood donors were invited to participate, and a total of 1891 participants were randomly assigned to either the experimental or control group. Participants were randomly assigned to either follow a blood bank's Facebook page or not. The study used a 2 (new Facebook followers vs non-Facebook followers) × 2 (premeasure vs postmeasure) mixed design, with an additional observational arm consisting of current Facebook followers (n=415). Outcomes were measured at 2 and 12 months following participation, incorporating both between- and within-participant comparisons. RESULTS: After 1 year, no significant interaction effects (group × time) were found for any of the attitudinal variables, including attitudes toward blood donation, intention to donate, attitudes toward the blood bank, perceived warmth and competence, contemplation of donorship, or contemplation of the blood bank. The experimental group was 32% more likely to have made a first donation (odds ratio [OR] 1.32, 95% CI 1.01-1.73) compared with the control group. Additionally, the experimental group made 12% more whole blood donations (incidence rate ratio [IRR] 1.12, 95% CI 1.01-1.24) and 17% more total donations (IRR 1.17, 95% CI 1.06-1.28) after 1 year than the control. No significant effects were observed for the observational group compared with the control group in terms of either whole blood donations or the total number of donations. Women were significantly more likely to donate more frequently (IRR 1.97, 95% CI 1.80-2.16) and less likely to discontinue their donor career (OR 0.52, 95% CI 0.37-0.72). Furthermore, older participants were slightly more likely to donate (OR 1.01, 95% CI 1.00-1.02). CONCLUSIONS: Our study provides initial evidence that regular engagement with a Facebook page can positively influence behavior in ways that offer meaningful benefits to organizations, including blood banks. While attitudinal effects appear limited, our findings demonstrate that social media efforts can nonetheless drive significant behavioral outcomes. Finally, we offer practical insights and actionable recommendations that blood banks and similar organizations can adopt to replicate these results and encourage prosocial behavior. TRIAL REGISTRATION: OSF Registries 10.17605/OSF.IO/2QGSU; https://osf.io/2qgsu.