Optimal selection of screening assays for infectious agents in donated blood

Blood products are an essential component of any health system, and their safety, in terms of being free of "transfusion-transmitted infections" (TTIs), i.e., diseases that include Human Immunodeficiency Virus, Hepatitis Viruses, Human T-cell Lymphotropic Virus, Syphilis, West Nile Virus, and Chagas' Disease, is crucial. However, blood screening tests are imperfectly reliable, with the possibility of false-negatives and false-positives. The budget-constrained decision-maker needs to (i) select a set of screening tests to administer to each unit of donated blood, and (ii) construct a "decision rule" with which to classify each blood unit as infection-free versus infected. The objective is to minimize the TTI risk for blood classified as infection-free, which depends on the efficacies of the entire set of tests selected and the decision rule adopted. This risk structure leads to a nonlinear optimization problem. Our analysis provides efficient optimal algorithms for a special case where only mono-infections are possible, and an effective heuristic and lower bounds for the general case with co-infection possibility. Our case study for the sub-Saharan Africa, Ghana, Thailand, and the United States illustrates the value of our optimization-based approach, which generates region-specific test composition by explicitly considering the regional TTI prevalence rates, and provides insights.