Tornado diagram shows the range of incremental cost-effectiveness ratios (ICERs) associated with variation in selected input variables. Ranges of input parameters are noted in parentheses. In the base case scenario, the ICER is calculated using a strategy of informed antigen-matching using a perfect assay (100% sensitivity, 100% specificity, and cost of $1000 per test), with history-based antigen-matching for C, E, and K as a reference strategy. Solid black line indicates the base-case ICER of $10,934 for each alloimmunization event averted. Variation in the ICER associated with varying a single input parameter is shown by each gray bar. Dashed black line reflects a threshold value of $50,000 per alloimmunization event averted. The extensive range of ICERs corresponding to variation in the assay specificity (40–100%) indicates that the cost-effectiveness of a potential assay is highly dependent on assay specificity.