Risks of red blood cell alloimmunization in transfusion-dependent β-thalassemia in Oman: a 25-year experience of a university tertiary care reference center and a literature review

BACKGROUND: β-Thalassemia is a common hemoglobinopathy in the Arabian Peninsula. Red blood cell (RBC) transfusion is a cornerstone for its management, but can create significant challenges including RBC alloimmunization. Herein, we examine alloimmunization risk factors in Omani patients with transfusion-dependent β-thalassemia. Existing literature is summarized. STUDY DESIGN AND METHODS: A retrospective review of all patients attending our center over 25 years was performed. Clinical and transfusion records were examined. Chi-square test was used to assess the association between the categorical variables. Nonparametric Mann-Whitney test was used to assess the association between transfusion and risk of alloimmunization. RESULTS: A total of 268 patients were identified (168 adults and 100 pediatrics), of whom 226 are alive (84.3%). Males accounted for 53.4%. The cohort had a median age of 22 years (range, 2-43 years). The most common blood group was O+ (39%). The prevalence of alloimmunization was 9.3% with anti-E (24%) and anti-K (24%) being the commonest antibodies identified. There was a significant association between age and alloimmunization, with 68% of alloimmunized patients in the age group of 19 to 30 years (p < 0.01). Among adults, there was a significant association between alloimmunization and number of units transfused (p = 0.001). There was no association between alloimmunization and sex or history of splenectomy. CONCLUSION: Our study shows an association between alloimmunization and the age of the patients and number of units transfused. Transfusion support of this group of patients necessitates the availability of needed expertise and blood bank facilities.