Characterization of pediatric transfusion-dependent thalassemia patients in a large academic center.

BACKGROUND: Transfusion-dependent thalassemia patients are at high risk of transfusion-related complications. Yet, there is scanty data on the frequency of transfusion reactions, particularity alloimmunization among pediatric transfusion-dependent thalassemia patients. In addition, there is no consensus on the prophylactic antigen matching for prevention of alloimmunization or the extent of antigen matching for alloimmunized thalassemia patients. METHODS: We conducted a retrospective study to assess the frequency and specificity of alloimmunization among pediatric transfusion-dependent thalassemia patients receiving ABO, RhD, and K-matched red blood cell units. In addition, we studied the association between patients' characteristics and alloimmunization. The clinical and transfusion records of transfusion-dependent thalassemia patients followed up at our institution between July 2018 and June 2022 were reviewed. RESULTS: Ninety-two transfusion-dependent thalassemia patients having mean age of 13.37 years (SD, 5.56) were included in our study. Eight patients (9%) had developed clinically significant alloantibodies; six patients (6%) developed alloantibody against E antigen while two patients (2%) developed more than one alloantibody. Of alloimmunized patients, five patients had received transfusion outside Canada. Patients' sex, age, having a genotype variant, total number, and duration of transfusion received were not associated with the risk of alloimmunization. The transfusion-recipient's diagnosis of ß-thalassemia, having developed autoantibody, and history of receiving transfusion outside Canada were associated with alloimmunization. CONCLUSION: Blood matching for ABO, RhD, and K antigens resulted in, although not eliminated, lower frequency of alloimmunization than that previously reported among pediatric thalassemia patients. Extending matching to include Rh antigens could further reduce the rate of alloimmunization.