Red cell alloimmunization and associated risk factors in multiply transfused thalassemia patients: A prospective cohort study conducted at a tertiary care center in Northern India.

Background: One of the complications of chronic transfusions in thalassemia is the development of red cell alloimmunization.

Aims: The aim of the study was to determine the frequency, specificity of red cell alloantibodies, and factors influencing alloimmunization in multiply transfused thalassemia patients.

Materials and methods: The study was carried out prospectively on beta-thalassemia patients over 10 months. Plasma samples were used for antibody screening and identification using the column agglutination technique. Patients' clinical, laboratory, and transfusion details were obtained from hospital information system and patient files.

Statistical analysis: Continuous variables were reported as median and quartile, whereas categorical variables were provided as numbers and proportions. P < 0.05 was considered statistically significant.

Results: Out of 255 patients, 17 (6.6%) patients developed alloantibodies. Alloimmunized patients had significantly higher median ages at their first transfusions (1 year vs. 0.5 years; P = 0.042) than nonalloimmunized patients. Alloimmunized patients had significantly higher conjugated bilirubin (P = 0.016) and serum ferritin (P = 0.007). The majority of alloantibodies had specificity toward K antigen, followed by E, C, D, JKa, and JKb antigens. Alloimmunized patients received more units per year than nonalloimmunized patients (median, 30 vs. 24 units; P < 0.001). The average transfusion interval time between two successive transfusions showed a significant difference (P < 0.001).

Conclusions: The prevalence of alloimmunization in thalassemia patients in North India is relatively low. Since most of the alloantibodies belong to Rh and Kell blood group system, extended phenotype-matched blood for Rh and Kell will be helpful in further preventing or decreasing the development of alloantibodies in multiply transfused thalassemia patients.