Acute GVHD, BK hemorrhagic cystitis and age are risk factors for transplant-associated thrombotic microangiopathy in adults.

Hematopoietic cell transplantation associated thrombotic microangiopathy (TMA) is a complication associated with higher non-relapse mortality (NRM) in allogeneic transplant (HCT) patients. Current classification criteria are not generally agreed upon or validated, and presence of confounding factors post-transplant contribute to under-diagnosis or delayed diagnosis of TMA. We studied risk factors, incidence and biomarkers of TMA in 119 adult allogeneic HCT recipients. Twenty-seven patients developed clinically actionable phenotype of TMA (CA-TMA) and the incidence of CA-TMA was 22% by day 180. Among the 27 patients that developed CA-TMA, 10 patients developed CA-TMA prior to onset of acute graft-versus-host disease (aGVHD) and 17 patients developed CA-TMA after the onset of aGVHD. We report for the first time that age > 50, BK hemorrhagic cystitis) and other viral infections (CMV, HHV-6, Adenovirus) are risk factors for adult CA-TMA. Even after adjusting for aGVHD, CA-TMA was independently associated with significantly higher non-relapse mortality. These data illustrate relationships between CA-TMA and aGVHD, describe new risk factors for CA-TMA and emphasizes the need to develop validated set of criteria for timely diagnosis.