Pediatric Transplant Associated Thrombotic Microangiopathy Healthcare Utilization and Implications of Eculizumab Therapy.

The healthcare utilization (HCU) burden of transplant associated thrombotic microangiopathy (TA-TMA) and its treatments are unknown. The objective of this study was to investigate inpatient costs associated with meeting criteria for transplant associated thrombotic microangiopathy (TA-TMA) in the first-year post-HCT. This IRB-approved retrospective multicenter study included serial children who underwent HCT from 1/1/2015 to 7/1/2019. A standardized unit cost (adjusted for geographic location, differences in cost of living, and inflation) for inpatient hospitalization was extracted from the Pediatric Health Information System data and linked to clinical data. Both total cost and cost-per-day from 15 days before stem cell infusion to 1-year post-HCT were calculated. Among children with neuroblastoma who underwent autologous HCT (n=60), 17 (28%) developed TA-TMA; there were no apparent differences in costs for TA-TMA versus no TA-TMA. Among allogeneic (allo) recipients, after adjusting for severe grade III/IV acute graft versus host disease (GVHD), infections, and HLA mismatch, costs were not different in TA-TMA (n=137) vs. no TA-TMA (n=238). Among allo HR-TMA-TMA, unadjusted costs were significantly higher in the eculizumab treated cohort (n=19, median $1,419,823, range $286,175 to $7,217,095) than supportive care (n=36, median $672,578 range $156,379 to $3,911,402, p=0.001). However, after adjusting for GI bleeding which occurred disproportionately in the eculizumab (n=6) versus supportive care (n=0) cohort, eculizumab treatment was not associated with increased total costs. More studies are needed to determine the etiology of increased HCU costs in those with HR-TA-TMA and to predict those more likely to benefit from eculizumab, reducing HCU and improving outcomes.