ABO Incompatibility and Hematopoietic Stem Cell Transplantation Outcomes.

The increased risk of hemolytic reactions and erythrocyte recovery delay in ABO incompatible hematopoietic stem cell transplantation (HSCT) are well established. Effects of ABO incompatibility on other transplantation outcomes are evaluated in this study. We prospectively followed 501 patients undergoing allogeneic stem cell transplantation regarding their ABO compatibility groups for a median time of 34.7 months. Patients were studied in minor, major and bidirectional mismatched and matched groups. Mean survival time (OS) was lower in minor mismatched group (p-value= 0.017). Minor and bidirectional mismatched groups received significantly more packed cell units than matched group (p-value < 0.0001 and p-value =0.002, respectively).Mean number of platelet unit infusion was significantly more in major mismatched recipients than matched group (p- value=0.031). Death rate was much more than expected in minor mismatched group. Two cases of PRCA (pure red cell aplasia) were found in major mismatched group. No statistically significant difference was found in the incidence of acute GVHD, chronic GVHD, time to neutrophil recovery, relapse- free survival, non-relapse mortality and relapse rate among groups. In order to prevent complications of ABO-incompatible SCT such as decrease in OS and the need for more transfusions, choosing ABO-compatible donors would improve transplantation outcomes.