Comparing Comorbidity Indices to Predict Survival After Pediatric Hematopoietic Stem Cell Transplantation for Nonmalignant Disease

BackgroundHematopoietic stem cell transplantation (HCT) is a potentially curative treatment for children with hematological or immunological disorders. However, treatment-related morbidity and mortality remain concerning. Various comorbidity indices are currently used to assess the risk of complications following pediatric HCT.ProcedureWe compared four comorbidity indices to determine which can most accurately estimate the risk of morbidity and mortality in pediatric nonmalignant HCT. We analyzed 308 pediatric allogeneic nonmalignant HCTs performed between January 2010 and December 2022. Four indices were evaluated: hematopoietic stem cell transplantation-specific comorbidity index (HCT-CI), youth nonmalignant hematopoietic stem cell transplantation comorbidity index (ynHCT-CI), simplified ynHCT-CI, and simplified comorbidity index (SCI). The primary outcome was overall survival (OS). The secondary outcome was graft-versus-host disease (GvHD)-free event-free survival (EFS), defined as acute GvHD Grade 3 or 4, extensive chronic GvHD, retransplantation, or death. The area under the receiver operator characteristic curve (AUC) was calculated per index and outcome at 100 days, 1 year, and 2 years post-HCT.ResultsFor OS, AUC values ranged from 0.611 to 0.755. The simplified ynHCT-CI and ynHCT-CI generally had superior discriminative abilities for OS, although no significant difference was found. For EFS, AUC values were between 0.539 and 0.632. The ynHCT-CI performed best for EFS, with AUC values of the simplified ynHCT-CI marginally lower. The ynHCT-CI significantly outperformed the HCT-CI at 100 days post transplantation (p = 0.045).ConclusionThe ynHCT-CI most accurately predicted outcomes after pediatric nonmalignant HCT. We propose the use of ynHCT-CI in future clinical management guidelines in this cohort.