Impact of ABO‐mismatch on outcome in bone marrow transplantation

Background ABO‐mismatch between donor and recipient of bone marrow transplantation (BMT) can impact clinical outcome. This is a retrospective single‐centre study that aimed to compare overall survival, transfusion requirements, time of neutrophil engraftment and the incidence of veno‐occlusive disease (VOD) and graft‐vs‐host disease (GVHD) in recipients of BMT with ABO‐match and mismatch. Methods We reviewed the charts of 140 recipients of related HLA full‐match BMT, between 1998 and 2014. We found 39 cases of ABO‐mismatch (27·9%), of which 21 (53·8%) with major, 14 (35·9%) with minor and 4 (10·3%) with bidirectional mismatch. Results ABO‐mismatch had no impact on survival, neutrophil engraftment and the incidence of VOD and acute GVHD. Minor mismatch patients had higher risk for chronic GVHD than major mismatch (P = 0·02). Median transfusions of red blood cell (RBC) units were 5 (0–57) and 10 (1–47) for match and mismatch groups (P = 0·004), and 12 (2–47) for major mismatch (P = 0·005). Median transfusions of platelet units were 46 (0–756) and 73 (0–429) for match and mismatch groups (P = 0·06). Conclusion ABO‐mismatch seems to be less frequent in Brazil. ABO‐mismatch had no significant impact on survival, neutrophil engraftment and VOD, but resulted in increased transfusion of RBC.