Incidence, risk factors, and outcomes of transplant-associated thrombotic microangiopathy in pediatric patients after allogeneic hematopoietic cell transplantation: a single-institution prospective study.

Transplant-associated thrombotic microangiopathy (TA-TMA) is an increasingly recognized complication in hematopoietic cell transplantation (HCT). Given the rarity of prospective pediatric studies on TA-TMA, this study aimed to evaluate the incidence, survival outcomes, and risk factors for predicting early the development of TA-TMA in a pediatric population following allogeneic HCT. We conducted a prospective analysis of 173 pediatric patients to evaluate the incidence, survival outcome, and risk factors of TA-TMA. The cumulative incidence of TA-TMA at one-year post-HCT was 4.7% (95% CI, 2.2-8.6%). Patients with TA-TMA showed significantly poorer 1-year overall survival (OS) rate, 50.0% ± 17.7% compared to 85.4% ± 2.8% in those without TA-TMA (p = 0.008). Additionally, the non-relapse mortality (NRM) rate was higher in the TA-TMA group at 12.5% (95% CI, 3.7-55.8%) versus 7.0% (95% CI, 2.8-10.1%) (p = 0.598). A urine protein/creatinine ratio ≥ 1 mg/mg on day 30 post-HCT was significantly associated with TA-TMA occurrence (adjusted HR, 9.5; [95% CI], 1.28-70.39; p = 0.028). This study showed the significantly unfavorable clinical outcomes associated with TA-TMA in pediatric patients and emphasized the importance of early identification of patients at risk. Further research is needed to explore additional strategies for early detection and intervention to improve outcomes.