Hematopoietic Cell Transplant Comorbidity Index Is Predictive of Survival after Autologous Hematopoietic Cell Transplantation in Multiple Myeloma

Abstract

Autologous hematopoietic stem cell transplantation (AHCT) improves survival in patients with multiple myeloma (MM) but is associated with morbidity and nonrelapse mortality (NRM). Hematopoietic cell transplant comorbidity index (HCT-CI) was shown to predict risk of NRM and survival after allogeneic transplantation. We tested the utility of HCT-CI as a predictor of NRM and survival in patients with MM undergoing AHCT. We analyzed outcomes of 1156 patients of AHCT after high-dose melphalan reported to the Center for International Blood and Marrow Transplant Research. Individual comorbidities were prospectively collected at the time of AHCT. The impact of HCT-CI and other potential prognostic factors, including Karnofsky performance score (KPS), on NRM and survival were studied in multivariate Cox regression models. HCT-CI score was 0, 1, 2, 3, and >3 in 42%, 18%, 13%, 13%, and 14% of the study cohort, respectively. Subjects were stratified into 3 risk groups: HCT-CI score of 0 (42%) versus HCT-CI score of 1 to 2 (32%) versus HCT-CI score > 2 (26%). Higher HCT-CI was associated with lower KPS < 90 (33% of subjects score of 0 versus 50% in HCT-CI score > 2). HCT-CI score > 2 was associated with melphalan dose reduction (22% versus 10% in score 0 cohort). One-year NRM was low at 2% (95% confidence interval, 1% to 4%) and did not correlate with HCT-CI score (P = .9). On multivariate analysis, overall survival was inferior in groups with HCT-CI score of 1 to 2 (relative risk, 1.37, [95% confidence interval, 1.01 to 1.87], P = .04) and HCT-CI score > 2 (relative risk, 1.5 [95% confidence interval, 1.09 to 2.08], P = .01). Overall survival was also inferior with KPS < 90 (P < .001), IgA subtype (P ≤ .001), those receiving >1 pretransplant induction regimen (P = .007), and those with resistant disease at the time of AHCT (P < .001). AHCT for MM is associated with low NRM, and death is predominantly related to disease progression. Although a higher HCT-CI score did not predict NRM, it was associated with inferior survival.