Economic evaluation of a hypothetical screening assay for alloimmunization risk among transfused patients with sickle cell disease

BACKGROUND: Prophylactic antigen-matching can reduce alloimmunization rates among chronically transfused patients with sickle cell disease (SCD), but this matching increases costs and may only benefit 30% of patients. We assessed the clinical and financial value of a potential assay for alloimmunization risk that would allow for targeted antigen-matching. STUDY DESIGN AND METHODS: A Markov-based model evaluated direct medical costs and alloimmunization events over 10 to 20 years among transfused (simple or exchange) patients with SCD. Four matching strategies were evaluated: prospective matching (for all patients), history-based matching (only for patients with prior alloimmunization), perfectly informed matching (assay with 100% sensitivity, 100% specificity), and imperfectly informed matching (reduced accuracy). Under all matching protocols, matching included C, E, K, and any additional alloantibodies present. A hospital perspective was adopted, with costs (2012US$) and events discounted (3%). RESULTS: Perfectly informed antigen-matching using a $1000 assay is expected to save $82,334 per patient over 10 years, compared to prospective matching. Perfectly informed antigen-matching is more costly than history-based matching, but reduces alloimmunization events by 45.6% over 10 years. Averting each alloimmunization event using this strategy would cost an additional $10,934 per patient. Imperfectly informed antigen-matching using an assay with 75% specificity and 75% sensitivity is less costly than prospective matching, but increases alloimmunization events. Compared to history-based matching, imperfectly informed matching would decrease alloimmunization events by 32.61%, at an additional cost of $147,915 per patient over 10 years. Cost-effectiveness of informed antigen-matching is largely driven by assay specificity. CONCLUSIONS: A sufficiently specific assay to inform antigen-matching may be cost-effective in reducing alloimmunization among transfused patients with SCD.