Screening red cell alloantibodies in SCA patients seen at MNH SCD clinics Dar es salaam, Tanzania

Abstract

Background: Red blood cell transfusion in sickle cell patients is a major form of supportive care and long term transfusion is recommended for patients with a risk of stroke. Many patients with SCA attend at MNH but no data are available on the frequency and pattern of alloantibodies among those frequently transfused. Objective: This study aimed at determining the frequency and pattern of red blood cell alloantibodies in sickle cell patients attending at MNH. Materials and Methods This was a descriptive cross -sectional study that was conducted at Muhimbili National Hospital between August and November 2009. Informed consent was obtained from the patients, their parents or guardians for those less than 18 years. Information on social demographic and clinical characteristics was collected from the medical files and interview from the parents or guardians. After physical examination, laboratory tests on blood were done for each study subject. ABO and Rhesus blood group and alloantibody screening were performed on every patient's sample and alloantibody identification on those found with positive screening test. The overall prevalence of RBC alloantibodies was determined and expressed as a percentage of all recruited patients during the time of data collection. All information was recorded using questionnaires and analysis was done using SPSS version 15. Results The study involved a total of 471 SCA patients aged 6 months and above attending paediatric and general haematology SCD clinic. Of these, 365 (77.5%) had of received a blood transfusion with 1184 total life time episodes transfusion (median, 2; range, 1-40).No records of transfusion documented in 106 (25.4%).The alloimmunization rate was 3.2% (15/471) among the SCA patients and 4.1% (15/365) of those who had been transfused. Anti-Kell was the most prevalent 20.7% and Rhesus blood group constituted 13.8% of total alloantibodies. The risk of alloimmunization was found to increase with episodes of RBC transfusion. Rather unusual that sickle and pregnancy did not elicit antibody development. Life threatening anaemia and splenomegaly were encountered in alloimmunized individuals.

V111 Conclusion The alloimmunization was evident among the transfused SCA patients. The presence of clinically significant alloantibody in transfused SCA patients shows the relevant role of RBC transfusion in the risk of alloimmunization Recommendations It is recommended that blood transfusion guideline be observed so that transfusion is appropriately used in management of SCA patients. This should involve an adequate pre- transfusion antibody screen and lA T cross-match. Policy of perfection would incorporate limited/partial phenotype matching of donor RBC for Kell, D, E and C prior to commencing chronic transfusion in order to minimize the risk of alloimmunization. Finally, further prospective studies are required to track the formation, clearance and features associated with alloimmunization in SCA patients.