Increased blood transfusion after outpatient autologous transplantation with reduced intensity conditioning for hematological malignancies predicts worse outcomes.

Transfusion has a recognized immunomodulatory effect, and its role on the outcomes after an ambulatory autologous hematopoietic stem cell transplantation (auto-HSCT) following reduced intensity conditioning (RIC) has not been documented. A study to assess factors associated with the number of packed red blood cells (PRBCs) and platelet units transfused and their impact on survival rates of auto-HSCT recipients after RIC was conducted between 2013 and 2019. Transfusions were recorded from days 0 to 100. Of the 130 patients studied, seventy (53.9%) required transfusion support. The median number of PRBC transfused was 2 (range 1-20), and for platelets, it was also 2 units (range 1-19). Infused CD34 + cells/kg, pre-transplant CMV status, and relapse/progression were significantly associated with the number of PRBC units transfused and sex, infused CD34 + cells/kg, and pre-transplant CMV status with the number of platelet units transfused. In multivariate analysis, a high/very high Disease Risk Index (P = .001) (P = .001) and transfusion of ≥ 5 total blood products (P = .001) (P = .010) were associated with decreased disease-free and overall survival. Two-year cumulative incidence of relapse was 50% for transfused patients vs. 34% for those not transfused (P = .009). These data suggest that the transfusion burden and its interplay with other patient and transplant-related factors could be associated with inferior auto-HSCT outcomes.