RESUMO
BACKGROUND: Blood transfusion is the first-line treatment for patients with thalassemia and many sickle cell patients. However, cases of unregulated blood transfusion are shown to carry a high risk of alloimmunization to red blood cells (RBCs), which can lead to a hemolytic transfusion reaction and be fatal to patients. Screening and identification of alloantibodies are, therefore, essential practice in blood transfusion services. Transfusion of phenotyped blood can minimize these risks to patients. STUDY DESIGN AND METHODS: A prospective study was carried out on 1015 donors, and a prospective and retrospective study was carried out on 208 multiple transfused patients with ß-thalassemia and sickle cell anemia. Donor and patient samples were subjected to Rh & K typing, and patient samples were also subjected to screening & identification of RBC antibodies. We aimed to determine the prevalence of RBC antigens in thalassemia and sickle cell patients, as well as blood donors, at King Abdulaziz University Hospital and the frequency of alloimmunization in the selected patients. RESULTS: The most commonly detected Rh-phenotype in donors was R1r (32.02%), followed by R1R1 (23.25%). Only 9.16% of donors were positive for the K antigen. The prevalence of Rh and K blood group antigens was also reported: the highest detected Rh-phenotype was R1r (40.86%) followed by R1R2 (24.04%) with only (6.25%) positive patients for K antigen. The rate of alloimmunization among sickle cell anemia and thalassemia patients was 39.42% and 35.57%, respectively. The highest specificity rates of the alloantibodies were recorded for anti-E and anti-K in both patient groups. CONCLUSION: The rate of alloimmunization in transfused patients was high and particularly observed against the Rh and K antigens. This study emphasizes the clinical need for typing patient RBCs prior to transfusion so as to provide phenotyped matched blood units and minimize the risks and associated morbidities of alloimmunization. Keeping a database of phenotyped blood donors is essential for the clinically effective and safe management of transfusion patients.
