Oral Abstract - Transfusion Medicine Service Operations
OA4-AM24-MN-15 - Incidence and Prevalence of Red Blood Cell Antibodies and Their Clinical Implications in Allogeneic Hematopoietic Stem Cell Transplantation: A BEST Collaborative Study
Background/Case Studies: Red blood cell (RBC) antibodies to non-ABO RBC antigens in allogeneic hematopoietic stem cell transplantation (HSCT), and their clinical implications have not been characterized.
Study
Design/Methods: This is an international retrospective study on HSCT from 2010 to 2021 including adult and pediatric patients, at 10 academic centers (9 United States, 1 Brazil). Recipients’ demographic characteristics, diagnoses, immunohematology, transfusion, and transplant details were collected from electronic medical records, laboratory information systems, and information provided to international transplant registries, or other transplant database. Institutional Review Board approval was obtained from all institutions. Descriptive statistics and multivariate logistic regression analysis with heteroskedasticity-robust standard errors were used.
Results/Findings: There were 9,156 HSCT events; 91.5% patients had 1 HSCT event and 8.5% had more than one. HSCT indications included acute myeloid leukemia (37.0%), acute lymphoblastic leukemia (13.0%), myelodysplastic syndrome (MDS) (13.0%), non-Hodgkin’s Lymphoma (11.0%) and others including hemoglobinopathies (25.6%). Graft sources were peripheral blood (76.2%), bone marrow (17.8%) and umbilical cord (5.8%). Conditioning regimen was myeloablative (49.3%) or non-myeloablative (50.7%). Donors were HLA matched-unrelated (40.5%), HLA matched-related (35.0%), or HLA mismatched (24.6%). HSCT events were ABO-compatible (55.7%), ABOi major (17.6%), ABOi minor (19.8%) or ABOi bidirectional (4.9%). 378 out of 9,156 (4.1%) HSCT events had RBC antibodies, including warm/cold autoantibody, passive transfer of anti-D, and alloantibodies with the most frequent specificities for antigens in the Rh (47%), Kell (13%) and Kidd (10%) systems (Table 1). Sickle cell disease HSCT indication had the highest rate of antibodies 26/161 (16.1%), followed by thalassemia 4/39 (10.3%), myeloproliferative neoplasia 16/192 (8.3%), and MDS 91/1,187 (7.7%). At 100 days post-HSCT, 136 out of 9,156 (1.5%) HSCT events demonstrated RBC antibodies with similar distribution of specificities to pre-HSCT. Regression estimates suggest that the presence of RBC antibodies pre- and post-HSCT was associated with increased RBC transfusions by 1.7-fold (p=0.047) and 6.7-fold (p=0.001), respectively, but not associated with increased platelet transfusion or delayed neutrophil engraftment. Conclusions: The prevalence and incidence of non-ABO RBC antibodies in HSCT events is 4.1% and 1.5% pre- and post-HSCT, respectively, and their presence is associated with increased number of RBC transfusions. Further study is underway to assess other clinically relevant complications, including hemolysis risk and engraftment kinetics.
