Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Babesiosis is the most common transfusion-transmitted infection in the US and frequently results in severe or fatal illness in immunocompromised blood recipients. Blood donor screening assays are currently investigational and not widely employed in endemic areas. We evaluated the cost-effectiveness of 4 screening strategies for prevention of transfusion-transmitted babesiosis.
Methods: A decision analytic model compared the cost-effectiveness of screening using (1) questionnaire (status quo) (2) universal immunofluorescence antibody (IFA) assay (3) universal IFA and polymerase chain reaction (PCR) and (4) recipient risk-based targeting whereby a proportion of blood is IFA/PCR screened and reserved for immunocompromised recipients. Data were from published sources, including the recently published 1 year experience of risk-based targeting at the Rhode Island Blood Center. A societal perspective with a time horizon of 1 year was adopted. Outcomes included screening and treatment costs, quality-adjusted life years (QALYs), and incremental cost-effectiveness (CE) ratios ($/QALY). Uncertainty was evaluated through 1-way, 2-way and probabilistic sensitivity analysis.
Results: In the base case, IFA screening had a CE ratio of $12,400 compared to status quo, IFA and PCR had an incremental CE ratio of $103,700 and the targeted strategy was excluded due to extended dominance. In 1-way sensitivity analyses the optimal screening strategy was sensitive to prevalence, testing costs, and the likelihood of donor window period infection. In probabilistic sensitivity analysis at a threshold of $100,000/QALY, IFA/PCR screening had a 55.7% probability of being the optimal strategy at 0.58% base case prevalence versus 2.1% at 0.1% prevalence and 91.5% at 1.4% prevalence.
Conclusions: Where babesia prevalence exceeds 0.1%, the CE ratio for IFA screening provides significantly better value for money than questionnaire and at prevalence exceeding 0.6% the incremental CE ratio for IFA/PCR screening is more attractive than many currently adopted blood safety interventions (Figure). More information on epidemiology and the accuracy of screening assays is needed to inform the optimal strategy for a national policy, but our results demonstrate a cost-effective means to improve blood safety in endemic areas. 