Age, GVHD prophylaxis, and timing matter in thrombotic microangiopathy after haematopoietic cell transplantation—A secondary CIBMTR analysis

Summary Most reports of risk factors (RF) for developing transplant‐associated thrombotic microangiopathy (TA‐TMA) and death are derived from paediatric and young adult cohorts, with minimal data on differences in RF and outcomes by age. In this secondary CIBMTR analysis, we used a previously prepared dataset that included all first allogenic haematopoietic cell transplantation (HCT) recipients with malignant or non‐malignant diseases between 2008 and 2016. The incidence of TA‐TMA 6 months post HCT was similar in children and adults 2.1% and 2.0% respectively. Grade 2–4 acute graft‐versus‐host disease (aGVHD) was a significant adjusted RF for developing TA‐TMA in both children and adults. In adults, additional adjusted RFs for TA‐TMA included female sex and black race, and in children an unrelated donor. Compared to a calcineurin inhibitor and sirolimus, other forms of GVHD prophylaxis had an adjusted decreased risk of developing TA‐TMA in adults. Adjusted RF for death in those with TA‐TMA ( n = 652) included age ≥18 years old, early onset of TA‐TMA diagnosis (<100 days post HCT), grade 3–4 aGVHD and a performance score of <90 prior to HCT. In this cohort, the incidence of TA‐TMA was similar in children and adults, and TA‐TMA timing was a newly identified RF for death.