Impact of Extended Red Blood Cell Antigen Typing on Alloimmunization in Multi-Transfused Patients: A Retrospective Study

Background: Alloimmunization is a complication of blood transfusion in which the recipient forms antibodies against the foreign antigens on the donor’s red blood cells (RBC), and it poses great difficulty in subsequent transfusion needs. Multi-transfused patients have an increased risk of RBC alloimmunization. Its adverse effects have led to the consideration of more advanced antigen matching for patients with a chronic need for transfusions. Objective: To assess the effect of extended antigen typing on the extended prevalence of RBC alloimmunization among multi-transfused patients in Saudi Arabian tertiary care hospital.Methods: A retrospective cohort study was conducted between January 2021 to December 2022, which included 120 patients on chronic RBC transfusions for any reason. The transfusion records, antibody screening, antigen typing, and demographic details were collected. Standard ABO and RhD transfusion-matched patients were placed into one group, while extended-AJT patients were placed into another group for more detailed statistical analysis. Statistical analysis was performed to determine the degree of association between selected clinical variables and the incidence of alloimmunization. Results: Almost every sixth patient (approximately 18%) with the transfusion history developed antibodies against foreign blood group antigens. In this study, the most common antibodies developed were anti-E (36.4%) and anti-K (27.3%). Transfusion burden above 10 significantly predicted even further increased alloimmunization (p = 0.02). There was a statistically significant reduction in the risk for alloimmunization with extended antigen matching (7.1%) compared to standard matching (p = 0.003).Conclusion: Incorporating extended antigen typing into clinical practice lowers the rate of alloimmunization amongst multi-transfused patients. It is advisable to incorporate it into the protocols of high-risk patients. Enhanced alloantigen matching capabilities might increase the safety of transfusions and improve health outcomes.