Frequency of Red Cell Alloimmunization in Patients with β-Major Thalassemia in an Iranian Referral Hospital

Objective: Frequency of red cell alloimmunization in patients with β-major-thalassemia in Mofid children's hospital. Tehran. Iran Material & Methods: This is a cross-sectional descriptive study conducted in Mofid children's hospital, March 2007. A total of 121 major thalassemia patients on regular blood transfusion were included in this study. Clinical and laboratory data were collected and analyzed to find out the frequency, pattern and factors influencing red cell immunization secondary to multiple blood transfusions in these patients. Findings: Mean age of patients was 13 (6.19) from 2-26 years.They had received regular blood transfusions during periods ranging from 1 to 25.5 years. Red cell alloimmunization was found in 9 patients (7.4%). In female group, 5 out of 66 (7.6%) patients and in male group 4 out of 55 (7.3%) patients had evidence of alloimmunization.The mean age of patients with alloimmunization was 9.6 (6.5) years (range 3.7-20). Four patients (44.4%) with alloimmunization were more than 3 years old at the time of first blood transfusion. The mean age at first blood transfusion in patients with alloimmunization and without alloimmunization was 2.8 (2.4) and 1.7 (2.0) years (P=0.1). The differential rate of splenectomy as a risk factor between patients with and without alloimmunization (11.1% and8% respectively) was not statistically significant (P=0.5). Direct or indirect antiglobulin tests were positive in 5 (62.5%) patients. The blood alloantibodies by a panel of antibodies using standardized blood bank methods were detected in 4 patients, which were of anti-K and anti-D types. Conclusion: The rate of red blood cell alloimmunization is relatively low in our patients. The age at first blood transfusion and splenectomy were not statistically significant as risk factors for alloimmunization in this study