Toward extended phenotype matching: a new operational paradigm for the transfusion service.

Background: Conventional pretransfusion testing uses hemagglutination to ensure donor-recipient compatibility for ABO/D status and recipient alloantibodies. While screening large numbers of donor units for multiple antigens by hemagglutination is impractical, novel methods of DNA analysis permit the rapid determination of an extended human erythrocyte antigen (xHEA) phenotype. A prospective observational study was conducted at four hospital transfusion services to test an alternative paradigm of identifying xHEA-typed units for patients in three cohorts by utilizing DNA analysis and a novel inventory management model.

Study Design And Methods: xHEA typing of recipient samples and donor units of known ABO/D status was performed by HEA analysis (BeadChip, BioArray Solutions). xHEA-typed units were assigned to pending transfusion requests using an inventory management system designed to simulate blood order processing. The fraction of requests fulfilled, or "fill fraction" (FF) was determined at four levels of matching stringency.

Results: For alloimmunized patients, all but one participating site observed an FF of more than 95% when matching for ABO, D, and known alloantibodies and an FF of more than 90% when additionally matching for C, c, E, e, and K; the site handling the most challenging requests still observed FFs of 62 and 51%, respectively. FF was found to correlate positively with the ratio of available donor units to units requested and negatively with the degree of recipient alloimmunization.

Conclusion: This study demonstrates that substantial fill fractions can be achieved by selecting existing donor units for xHEA analysis and operating an inventory management system for efficient allocation of units to recipients.