HCT ‐ FS ‐Defined Frailty Is Associated With Lower Survival Across Diverse Hematologic Diagnoses After Allogeneic Transplantation

OBJECTIVES: To evaluate whether Hematopoietic Cell Transplantation Frailty Scale (HCT-FS)-defined frailty predicts overall survival (OS), nonrelapse mortality (NRM), and relapse across diverse hematologic diagnoses undergoing allogeneic hematopoietic cell transplantation (alloHCT), including nonmalignant disorders. METHODS: We conducted a multicenter retrospective cohort study of 992 adults undergoing alloHCT at 16 centers in Canada and Spain (2018-2023). Frailty was assessed at consultation using the HCT-FS (fit, prefrail, frail). OS was estimated by Kaplan-Meier, competing-risks methods by cumulative incidence. Multivariable models assessed associations with OS and NRM. RESULTS: Frailty was assessed across six diagnostic categories, including nonmalignant disorders (4.8%). At consultation, 32.1% were fit, 54.7% prefrail, and 13.2% frail. Increasing frailty was associated with progressively lower 2-year OS (78.9%, 66.0%, 51.7%; p < 0.001) and higher 2-year NRM (10.5%, 18.9%, 33.2%; p < 0.001; HR 1.77 [95% CI 1.21-2.60] prefrail and 3.65 [2.36-5.65] frail vs. fit), while 2-year relapse incidence did not differ (19.0%, 23.5%, 22.3%; p = 0.229). Disease-specific estimates were exploratory and limited by small subgroup sizes. CONCLUSIONS: HCT-FS-defined frailty is associated with OS and NRM but not relapse in this multicenter alloHCT cohort. Larger disease-specific studies are needed to establish its prognostic value in less represented indications.