Comorbidity Index (CI) in Autologous Hematopoietic Cell Transplantation (HCT) for Malignant Diseases: Validation of the HCT-CI

Abstract ⁸¹⁴

Comorbid conditions measured by the HCT-CI are associated with higher transplant-related (TRM) and overall mortality among allogeneic HCT recipients. However, the HCT-CI has not been validated for recipients of autologous HCT, who are frequently older and whose TRM is much lower than allogeneic HCT. We analyzed the impact of the prospectively collected HCT-CI on post-transplant TRM and overall survival for 11,652 recipients of autologous HCT between December 2007 and December 2009 reported to the CIBMTR from 151 US centers. Patients' median age was 56 years, 62% had Karnofsky score (KPS) ≥90% and the median time from diagnosis to transplant was 11 months. Multiple myeloma (MM, 49%) and lymphoma (41%) were the most common diagnoses, and peripheral blood was the graft source for 99%. Comorbidities that compose the HCT-CI were present in 49% of patients and the most commonly reported were: pulmonary (moderate –13%, severe – 8%), psychiatric conditions (11%) and insulin dependent diabetes mellitus (8%). The HCT-CI score ranged from 0 to 15 and was classified into: 0 (n=5,851), 1–2 (n=3,089) and ≥3 (n=2,645).Overall, the cumulative incidence of TRM at 1 and 3 years was 3% (95% Confidence Interval [CI] 3–4%) and 6% (95% CI – 6–7%). Corresponding probabilities of overall survival (OS) were 89% (95% CI 89–90%) and 76% (95% CI 75–77%), respectively. Three-year cumulative incidence of TRM according to HCT-CI scores of 0, 1–2 and ≥3 were 5%, 6% and 9%, respectively, (p<0.001) while corresponding 3-year OS probabilities were 79%, 73% and 70% (p<0.001), respectively. Subgroup analysis in patients with MM and lymphoma demonstrated similar effect of HCT-CI on survival outcomes. Cox regression multivariate analysis for TRM and overall mortality adjusted for patient, transplant and disease characteristics are shown below. Additional factors associated with increased risk of TRM include: age, KPS, disease and disease status. Incremental greater HCT-CI scores were associated with increased risk of TRM and overall mortality after autologous transplantation. The effect on overall survival was more significant than in TRM, which is likely related to relatively lower number of TRM events after autologous HCT. The HCT-CI is a validated tool to predict survival outcomes after autologous HCT based upon patient comorbidities, and can be used to stratify risk when counseling patients about outcomes of HCT, adjusting statistical analyses of transplant outcomes and in clinical trial design.