Hematopoietic cell transplantation specific comorbidity index as an outcome predictor for patients with acute myeloid leukemia in first remission: combined FHCRC and MDACC experiences

Abstract

A new hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was effective in predicting outcomes among patients with hematologic malignancies who underwent HCT at Fred Hutchinson Cancer Research Center (FHCRC). Here, we compared the performance of the HCT-CI to 2 other indices and then tested its capacity to predict outcomes among 2 cohorts of patients diagnosed with a single disease entity, acute myeloid leukemia in first complete remission, who underwent transplantation at either FHCRC or M. D. Anderson Cancer Center (MDACC). FHCRC patients less frequently had unfavorable cytogenetics (15% versus 36%) and HCT-CI scores of 3 or more (21% versus 58%) compared with MDACC patients. We found that the HCT-CI had higher sensitivity and outcome predictability compared with the other indices among both cohorts. HCT-CI scores of 0, 1 to 2, and 3 or more predicted comparable nonrelapse mortality (NRM) among FHCRC and MDACC patients. In multivariate models, HCT-CI scores were associated with the highest hazard ratios (HRS) for NRM and survival among each cohort. The 2-year survival rates among FHCRC and MDACC patients were 71% versus 56%, respectively. After adjustment for risk factors, including HCT-CI scores, no difference in survival was detected (HR: 0.98, P = .94). The HCT-CI is a sensitive and informative tool for comparing trial results at different institutions. Inclusion of comorbidity data in HCT trials provides valuable, independent information.

Figure 1

The distribution of individual comorbidities. Individual comorbidities among (A) FHCRC and (B) MDACC patients as captured by each of the 3 indices, the HCT-CI, the ACE-27, and the CCI.

Figure 2

Cumulative incidences of NRM. Comparison of NRM among FHCRC and MDACC patients as stratified by HCT-CI scores of (A) 0, (B) 1 to 2, and (C) 3 or more. Solid lines represent FHCRC patients; dashed lines represent MDACC patients.

Figure 3

Kaplan-Meier curves for overall survival. OS as stratified by HCT-CI scores of 0, 1 to 2, and more than or equal to 3 among patients transplanted in (A) FHCRC and (B) MDACC.

Figure 4

Correlation between HCT-CI scores and age. Distribution of HCT-CI scores of 0, 1 to 2, and 3 or more among 4 age categories; less than 40, 40 to 49, 50 to 59, and more than 59 years of all patients (n = 224) with AML in first CR transplanted at FHCRC and MDACC. HCT-CI score 0, white area; HCT-CI scores 1 to 2, gray area; HCT-CI scores more than or equal to 3, black area.