Safety of ABO-incompatible Platelet Transfusions: A Multicenter Retrospective Cohort Study

Objectives: It is not always possible to access ABO-compatible platelet concentrates (PCs) for reasons such as short shelf life and not always being readily available. Therefore, blood centers have to develop strategies for the use of ABO-incompatible PCs. However, there are conflicting data regarding the safety of using ABO-incompatible platelet transfusions, especially concerning transfusion reactions. Methods: This multicenter, retrospective cohort study analyzed platelet transfusion records from 3 tertiary-level hospitals over a 9-year period (2016-2024). Data were extracted from institutional hemovigilance systems and electronic transfusion records. The transfusion outcomes were compared between ABO-compatible and ABO-incompatible PCs, focusing on the incidence of transfusion reactions (TRs). Results: A total of 21,470 PCs were transfused to 12,305 patients. TRs occurred in 17 cases, with an incidence of 0.79 per 1000 PCs. Of these reactions, 7 were febrile nonhemolytic transfusion reactions and 10 were allergic reactions. During the study period, 2791 ABO-incompatible PCs (12.9%) were transfused to 1248 patients. No significant difference was determined in the transfusion reaction rate between the ABO-compatible and incompatible groups (0.80 per 1000 vs. 0.71 per 1000, P =0.88). The distribution of TR types was similar in both groups ( P =0.787). No hemolytic reaction was observed. Conclusion: Although no significant difference in TR incidence was detected between ABO-compatible and incompatible PCs, this retrospective study—limited by low event frequency, and potential under-reporting—was not able to establish the safety of ABO‑incompatible transfusions. However, ABO-incompatible PCs may still be an option in resource-limited settings. Larger-scale prospective studies are necessary to further evaluate safety with standardized hemovigilance reporting.