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

Structured AbstractO_ST_ABSBackgroundC_ST_ABSCivilian walking blood banks (WBBs) transfuse fresh whole blood from mobilized donors, 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 a RDT process instead of a more traditional, laboratory-based test persist. We aimed to understand the marginal risk of TTI using an RDT-based strategy compared to a laboratory-based test through development of a simulation model and accompanying online tool. Study Design and MethodsWe modeled expected TTIs per 100,000 donations from initial collection to transfusion and seroconversion. Parameters included TTI prevalence, donor risk-stratification, efficacy of stratification tools, TTI testing rates, platform test performance, and probability of seroconversion. ResultsA baseline TTI prevalence of 1% (95% 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. DiscussionIn 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.