CONSORT diagram. A total of 506 patients underwent HCT during the study period. Allogeneic recipients were analyzed separately from autologous HCT recipients, and gene therapy recipients were excluded from the analysis. All patients who met criteria for TA-TMA were risk stratified into HR- TA-TMA or SR- TA-TMA. Patients were stratified as being at high risk if they had sC5b-9 level > the upper limit of normal and proteinuria > 2 mg/mg or either elevated sC5b-9 or proteinuria and multiorgan dysfunction. Among patients with HR-TA-TMA, patients were treated with either eculizumab or supportive care only.