Pre-transplant Clostridioides difficile infection predicts subsequent gastrointestinal GVHD and non-relapse mortality after allogeneic hematopoietic stem cell transplantation.

This study aimed to define the incidence of Clostridioides difficile infection (CDI), identify its risk factors, and evaluate its association with early post-transplant complications and overall clinical outcomes. To characterize CDI in the allogeneic hematopoietic stem cell transplantation (allo-HSCT) setting, we retrospectively analyzed a cohort of 539 recipients who experienced diarrhea in the peri-transplant period (from conditioning to discharge from laminar flow). Among these diarrheic recipients, 64 patients developed CDI, the cumulative incidence of CDI was 12.1%, with a median onset of day -1 (range, -7 to +26) relative to HSCT. In a multivariate analysis, older age was independently associated with a lower risk of CDI (HR, 0.97; P = 0.008) among diarrheic recipients. The incidence of CDI stratified by the median onset time revealed that pre-transplant CDI was an independent risk factor for grade 1-4 lower gastrointestinal acute graft-versus-host disease (lower-GI aGVHD) (HR, 2.43; P=0.024). Furthermore, pre-transplant CDI was associated with a markedly increased risk of severe fungal infection (HR,6.97; P=0.026) and 100-day non-relapse mortality (NRM) (HR, 3.13; P=0.046). In conclusion, this study highlights a critical, timing-dependent distinction in CDI-associated severe complications and mortality in allo-HSCT recipients with diarrhea.