Risk of alloimmunization and delayed hemolytic transfusion reactions in patients with sickle cell disease.

Blood transfusion is an integral part of the supportive care of patients with sickle cell diseases. The hazards of red blood cell alloimmunization and delayed hemolytic transfusion reactions (DHTRs) complicate the treatment of patients with sickle cell diseases, particularly since such reactions may be misinterpreted as a pain crisis, and, as a result, specific transfusion serologic studies may not be performed. The frequency of alloimmunization in this population has been the subject of several reports; however, the frequency of DHTRs is unknown. To determine the frequency of this event, we retrospectively reviewed the medical and transfusion service records of all adult patients with sickle cell diseases transfused during the six-year period from January 1980 to December 1985. Seventy-three adult patients with sickle cell diseases received transfusions. The prevalence of recognized DHTR was three (4%) of 73. Red blood cell alloimmunization was seen in 22 (30%) of 73 of the patients. The calculated risk of alloimmunization was 3.1% per unit of blood. These observations suggest that alloimmunization and clinically apparent DHTRs occur more frequently in patients with sickle cell diseases and support pretransfusion testing for at least Rh and Kell red blood cell antigens in patients who are at high risk of such events (patients who have formed an alloantibody or who are being enrolled in a transfusion program).