Abstract
Blood transfusion in patients with sickle cell disease (SCD) is limited by the development of alloantibodies to erythrocytes. In the present study, the frequency and risk factors for alloimmunization were determined. Transfusion records and medical charts of 828 SCD patients who had been transfused and followed at the Belo Horizonte Blood Center, Belo Horizonte, MG, Brazil, were retrospectively reviewed. Alloimmunization frequency was 9.9% (95% CI: 7.9 to 11.9%) and 125 alloantibodies were detected, 79% of which belonged to the Rhesus and Kell systems. Female patients developed alloimmunization more frequently (P = 0.03). The median age of the alloimmunized group was 23.3 years, compared to 14.6 years for the non-alloimmunized group (P < 0.0001). Multivariate analyses were applied to the data for 608 hemoglobin (Hb) SS or SC patients whose number of transfusions was recorded accurately. Number of transfusions (P = 0.00006), older age (P = 0.056) and Hb SC (P = 0.02) showed independent statistical associations with alloimmunization. Hb SC patients older than 14 years faced a 2.8-fold higher (95% CI: 1.3 to 6.0) risk of alloimmunization than Hb SS patients. Female Hb SC patients had the highest risk of developing alloantibodies. In patients younger than 14 years, only the number of transfusions was significant. We conclude that an increased risk of alloimmunization was associated with older patients with Hb SC, specially females, even after adjustments were made for the number of transfusions received, the most significant variable.
Highlights
Sickle cell anemia is one of the most common hereditary diseases in Brazil [1]
For those below 14 years, only the number of transfusions remained statistically significant in multivariate analysis (P = 0.0001). For those above 14 years, number of transfusions (P = 0.04) and type of sickle cell disease (SCD) (P = 0.008) remained significant in multivariate analysis. These Hb SC patients were at a 2.8fold higher risk of alloimmunization than SS patients
The objective of the present study was to determine the frequency of alloimmunization to red blood cell (RBC) antigens in patients with SCD who had been transfused at a large Brazilian Blood Center located in Belo Horizonte, MG, Brazil, and the possible association between alloimmunization and the number of transfusions, age, gender, and Hb phenotype
Summary
Sickle cell anemia is one of the most common hereditary diseases in Brazil [1]. Its true incidence is unknown, it is estimated that 2 to 8% of the Brazilian population harbor the sickle cell trait, according to the intensity of the migratory flow of the black population in each region. It is estimated that more than two million Brazilians carry the sickle cell trait and more than 8,000 present the homozygous hemoglobin (Hb) SS disease [1]. Due to the high morbidity of sickle cell disease (SCD) and limitations of the therapeutic options, many patients receive transfusions for the various complications that ensue.
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