LAUSR

High rates of alloimmunization have been observed among patients requiring chronic red blood cell (RBC) transfusions, especially those with sickle cell disease (SCD) and thalassemia. 1-3 Alloimmunization in SCD increases the risk of hemolytic transfusion reactions, complicates procurement of compatible RBCs, and is associated with worse clinical outcomes. 2,3 Beyond the SCD patient population, the economic and clinical impacts of alloimmunization are not as clear. Previous studies, largely focusing on the SCD population, have reported that transfusion of RBCs that are phenotypically matched to the transfusion recipient may reduce the incidence of alloimmunization. 4-10 Current RBC transfusion guidelines recommend Rh (D,C,c,E,e) and K antigen matching for patients with SCD and thalassemia who are regularly transfused. 11-13 Expert opinion suggests extended prophylactic antigen matching beyond Rhand K could provide additional protection against alloimmunization, but data to con fi rm this suggestion are limited. 4-10 The present study evaluates the association between alloimmunization and worsened economic and clinical outcomes in hospitalized patients with SCD and thalassemia, as well as anemia from other causes such as bleeding and bone marrow hypoplasia. This nested case-control study used the Premier chargemaster dataset,