HCT Frailty Scale (HCT-FS) for Assessing Frailty in Allogeneic Hematopoietic Cell Transplant Patients. Results from a Canadian and Spanish Initiative

INTRODUCTION : This collaborative study aims to present the results obtained from the implementation of the Hematopoietic Cell Transplantation Frailty Scale (HCT-FS) for the assessment of frailty in adult candidates for allogeneic hematopoietic cell transplantation (allo-HCT) at 16 independent HCT Units. METHODS : Sixteen allo-HCT programs (1 in Canada, 15 in Spain) participated. Frailty was systematically assessed at the first allo-HCT consultation using the HCT-FS (https://hctfrailtyscale.com) and incorporated into routine clinical practice at each center without external funding. RESULT S: A total of 1,077 consecutive adult allo-HCT candidates (median age: 56 years) were evaluated. Based on the HCT-FS, 33.4% were classified as fit, 53.7% as pre-frail, and 12.8% as frail. Frailty was associated with longer hospital stays during allo-HCT (28 days vs. 23 and 25; P = 0.003) and higher ICU admission rates by day + 180 (20.3% vs. 7.0% and 10.8%; P = 0.002). Two-year OS decreased progressively with increasing frailty: 77.2% in fit, 65.7% in pre-frail, and 52.8% in frail patients (P < 0.001). Corresponding non-relapse mortality (NRM) rates were 11.7%, 19.5%, and 32.2%, respectively (P = 0.001). Multivariable analysis confirmed frailty as an independent predictor of inferior OS and increased NRM, even when adjusting for age, comorbidities, performance status, disease risk, and donor type.The HCT-FS maintained robust prognostic accuracy across subgroups stratified by age and comorbidity burden, supporting its broad applicability in clinical practice regardless of patients’ baseline characteristics. CONCLUSION : The HCT-FS provides reliable measures of the frailty status of allo-HCT candidates that are informative in anticipating transplant outcomes, particularly risk of OS. Its use is recommended in clinical practice for pre-transplant assessments.