Alloimmunization Rates and Associated Factors in Transfusion-Dependent Patients: a Regional Study from Saudi Arabia

BACKGROUND: Blood transfusion is effective in treating and managing numerous medical conditions. However, repeated transfusions increase the risk of alloimmunization. This study aimed to determine the prevalence and risk factors associated with alloimmunization in transfusion-dependent patients in the Aseer province. METHODS: This study included 149 patients. Data were obtained retrospectively from medical records and include age, gender, diagnosis, blood group, Rh phenotype, presence of alloantibodies, and transfusion history. RESULTS: Out of the 149 patients, 78 (52.3%) were male and 71 (48.6%) were female, with a mean age of 24.58 ± 23.21 years (range 1 - 88 years). Alloimmunization was detected in 15 (10.2%) patients, predominantly in those with blood group O (8, 53%) and Rh-D positive status (12, 80%). A significant proportion (12, 80%) had received > 15 transfusion units per year. The most frequently identified alloantibodies were anti-E (4, 26%) and anti K (4, 26%). Alloimmunization was significantly associated with age, Rh-D blood group, and the number of transfusion units received (p ≤ 0.05). CONCLUSIONS: Transfusion-dependent patients are at increased risk of alloimmunization, particularly those with Rh-D positivity, older age, and a high transfusion burden. The risk of alloimmunization could be mitigated by implementing extended red cell phenotyping and matched transfusion strategies. These findings underscore the need for optimized transfusion policies to minimize alloimmunization-related complications in this vulnerable patient population.