Transfusion Requirements in Allogeneic Hematopoietic Cell Transplantation (HCT) Recipients Given Either Myeloablative or Nonmyeloablative Conditioning, and Effect of ABO Incompatibility on HCT Outcomes.
Authors: Wang Zejing , Sorror Mohamed L. , Leisenring Wendy , Schoch Gary , Malonely David G. , Sandmaier Brenda M. , Storb Rainer F. 
Published: October 2019

Abstract
We retrospectively assessed 1) overall platelet (PLT) and red blood cell (RBC) transfusion requirements within the first 100 days after allogeneic among HCT recipients given either nonmyeloablative (n=365) or myeloablative conditioning (n=1430); 2) transfusion requirements among nonmyeloablative recipients given grafts from related (n=187) vs. unrelated donors (n=178), and grafts from ABO matched (n=203) vs. ABO mismatched donors (n=159); and 3) the impact of ABO incompatibility on HCT outcomes among nonmyeloablative recipients. Table 1 summarizes results. We confirmed that myeloablative recipients were more likely to receive both PLT and RBC transfusions than nonmyeloablative recipients (both p<0.0001). Subsequent analyses were restricted to nonmyeloablative recipients. Both PLT and RBC transfusion requirements were increased among recipients of unrelated grafts (both p<0.0001) and those with major or bi-directional ABO mismatched grafts (p = 0.019 and p=0.003, respectively). No statistically significant differences were observed in cumulative incidences of graft rejection/failure, grades II-IV acute GVHD and in 3-year survivals between ABO-matched, minor-mismatched, and major/bidirectional mismatched pts (p=0.89, 0.48, and 0.49, respectively). Times to disappearance of anti-donor IgM and IgG isohemagglutinins were not statistically significantly different among major or bi-directional ABO mismatched related (43 days for both) vs. unrelated recipients (58 and 57 days, p=0.20 and 0.27, respectively). Major/bidirectional ABO-mismatched recipients with grades II-IV vs. 0–I acute GVHD had comparable likelihoods of reaching IgM (p=0.20) and IgG (p=0.63) titer endpoints. In conclusion, nonmyeloablative pts had reduced PLT and RBC transfusion requirements compared to myeloablative pts. Among nonmyeloablative pts, unrelated (vs. related) grafts and ABO-incompatibility (vs. ABO compatibility) between donors and recipients led to increased PLT and RBC transfusion requirements. ABO incompatibility did not increase graft rejection nor GVHD or adversely affect survival after non-myeloablative HCT. The tempo of disappearance of anti-donor isohemagglutinin titers was not influenced by donor type or occurrence of GVHD.
Table 1. Percentage of patients requiring at least one PLT or RBC transfusion.
% of Patients Requiring Transfusions N PLT p-value† RBC p-value† † p-value from Chi-square test. * Reference group for comparisons. £ Information were missing from 3 patients. Non-myeloablative 365 36% * 76% * Myeloablative 1430 99% <0.0001 96% <0.0001 Non-myeloablative Related grafts 187 25% * 67% * Unrelated grafts 178 47% <0.0001 86% <0.0001 Non-myeloablative£ ABO-matched 203 33% * 70% * ABO minor mismatched 79 33% 0.95 80% 0.11 Major bi-directional ABO-mismatched 80 48% 0.019 88% 0.003 Non-myeloablative ABO-mismatched Related grafts 66 32% * 77% * Unrelated grafts 93 46% 0.068 88% 0.067