The risk of transfusion transmissible infection in a civilian walking blood bank using rapid diagnostic tests: A modeling study

BACKGROUND: Civilian walking blood banks (WBBs) can transfuse fresh whole blood from mobilized donors who are screened using rapid diagnostic testing (RDT) for transfusion transmissible infections (TTIs) to preserve life when banked blood is unavailable. However, concerns regarding TTI risk using an RDT process instead of laboratory-based testing methods persist. We aimed to understand the additional risk of TTI using an RDT-based strategy compared to a laboratory-based strategy with a simulation model and accompanying online tool. STUDY DESIGN AND METHODS: We modeled expected TTIs per 100,000 donations from initial collection to transfusion and infection. Parameters included TTI prevalence, donor risk stratification, efficacy of stratification tools, TTI testing rates, platform test performance, and probability of infection. RESULTS: A baseline TTI prevalence of 1% (95% confidence interval [CI]: 0.25%, 1.75%) resulted in 56 TTIs (95% CI: 23, 91) when the RDT sensitivity was 90% (95% CI: 88%, 92%), 30 TTIs (95% CI: 12, 52) when the RDT sensitivity was 95% (95% CI: 93%, 97%), and 12 TTIs (95% CI: 4, 23) when the RDT sensitivity was 99% (95% CI: 97, 100%) per 100,000 donations. Compared to lab-based testing, 15,351 donations would need to be made under a high-sensitivity RDT testing strategy in order to incur one additional TTI. DISCUSSION: In a simulated WBB model, modern RDT platforms demonstrated favorable test characteristics, with low absolute rates of TTI, particularly when low-risk donors are selected. These findings support WBB implementation as an emergency transfusion strategy in settings lacking banked blood.