Age-Related Differences in Utilization of Allogeneic HCT for Acute Myeloid Leukemia in California: Results of a Population-Based, Novel Linked Dataset

Background Acute myeloid leukemia (AML) predominantly affects older adults, and often requires allogeneic hematopoietic cell transplantation (alloHCT) for cure. According to the Center for International Blood and Marrow Transplant Research (CIBMTR), beginning in 2001, the largest growth in alloHCT for malignant diseases occurred in patients ≥65y. However, whether this is due to expanded utilization of alloHCT for AML is unclear. Using a linked dataset, we examined patients with AML in California to assess population-based alloHCT utilization over time and factors associated with receipt of alloHCT across age groups. Methods Data obtained from a linkage between the CIBMTR database, California Cancer Registry and Patient Discharge Data (PDD) included adolescents and young adults (AYA, 15-39y), adults (40-64y) and older adults (65-79y) with AML diagnosed between 2001-2016. Multivariable Fine-Gray regression analyses accounting for the competing risk of death were modeled separately across age cohorts. Results 7,925 patients with newly diagnosed AML were included. Examination of alloHCT utilization over time demonstrated that the use of alloHCT has increased within each age cohort (Figure 1). Although utilization among patients 65+ increased from 2% to 13%, the change was lowest in this age group and remains lower than AYA and adult patients. Multivariable models (Figure 2) demonstrate that patient-level variables associated with alloHCT utilization vary by age group. For AYAs: utilization was lower for low/middle SES relative to high SES, uninsured, and those covered by Indian health services relative to private insurance whereas utilization was higher for males, and more recent year of diagnosis; Adults: utilization was lower for patients with increased age, male sex, non-Hispanic Black or Asian race/ethnicity relative to non-Hispanic White, unmarried status relative to married, low/middle SES relative to high, uninsured, Medicaid, Medicare, and Indian health services, and 1+ comorbidities compared to 0, whereas it was higher for more recent diagnosis year and patients living <50 miles distance from a transplant center relative to 100+ miles; and Older adults: utilization was lower for patients with increased age, Asian race/ethnicity, and unmarried status, whereas higher utilization was associated with more recent diagnosis year. Conclusions Using a novel population-based linked database of newly diagnosed AML patients in California, we found that alloHCT utilization increased in all age cohorts over time; however, fewer than 14% of older adults who received leukemia induction ultimately received alloHCT even in the most recent era studied. As potential patient-level barriers to alloHCT differ across age groups, studies should explore further modifiable age-related factors and develop age-specific interventions to mitigate barriers to alloHCT utilization.