Transplant-associated Thrombotic Microangiopathy: Incidence, Prognostic Factors, Morbidity, and Mortality in Allogeneic Hematopoietic Cell Transplantation

Renewed interest has emerged in transplant-associated thrombotic microangiopathy (TA-TMA) with novel prognostic, diagnostic, and treatment algorithms. We aimed to investigate the incidence, prognostic factors, morbidity, and mortality of TA-TMA in allogeneic hematopoietic cell transplantation (HCT) recipients. We enrolled consecutive HCT recipients (1990-2017). Among 758 patients, 116 (15.5%) were diagnosed with TA-TMA. In the multivariate analysis, TBI-based conditioning, viral infections, acute and chronic GVHD remained independent predictors of TA-TMA. With a median follow-up of 23 (range 0.1-329) months, TA-TMA resulted in significantly lower overall survival (OS). In the multivariate analysis, TA-TMA remained an independent predictor of OS, along with relapse, acute, and chronic GVHD. Among 116 TA-TMA patients, 70 developed renal (56) and/or neurologic (26) dysfunction that would be necessary for TA-TMA diagnosis according to the Bone Marrow Transplant Clinical Trials Network criteria. TA-TMA patients with renal dysfunction showed increased rates of acute GVHD, but no difference in OS compared to patients without renal dysfunction. However, neurologic dysfunction resulted in significantly lower OS. In conclusion, TA-TMA is associated with increased morbidity and mortality in allogeneic transplant recipients. Successful prevention and treatment strategies of infections and GVHD need to be timely employed to improve survival in this complex setting.