Background: The purpose of this study was to investigate the prognostic importance of functional capacity in patients undergoing allogeneic hematopoietic cell transplantation (HCT) for hematological malignancies.
Patients and methods: Using a retrospective design, 407 patients completed a 6-minute walk distance (6 MWD) test to assess functional capacity before HCT; 193 (47%) completed a 6 MWD test after hospital discharge. Cox proportional hazards regression was used to estimate the risk of nonrelapse mortality (NRM) and overall survival (OS) according to the 6 MWD category (<400 m vs. ≥ 400 m) and the change in 6 MWD (before HCT to discharge) with or without adjustment for Karnofsky performance status (KPS), age, and other prognostic markers.
Results: Compared with <400 m, the unadjusted hazard ratio for NRM was 0.65 (95% confidence interval, 0.44-0.96) for a 6 MWD ≥ 400 m. A 6 MWD of ≥ 400 m provided incremental information on the prediction of NRM with adjustment for age (p = .032) but not KPS alone (p = .062) or adjustment for other prognostic markers (p = .099). A significant association was found between the 6 MWD and OS (p = .027). A 6 MWD of ≥ 400 m provided incremental information on the prediction of OS with adjustment for age (p = .032) but not for other prognostic markers (p > .05 for all). Patients presenting with a pre-HCT 6 MWD of <400 m and experiencing a decline in 6 MWD had the highest risk of NRM.
Conclusion: The 6 MWD is a significant univariate predictor of clinical outcomes but did not provide prognostic information beyond that of traditional prognostic markers in HCT.
Implications for practice: The pretransplant 6-minute walk test is a significant univariate predictor of clinical outcomes in hematological patients beyond age but not beyond that of performance status. On this basis, 6-minute walk distance testing should not be considered part of the standard battery of assessments for risk stratification before hematopoietic cell transplantation.
Keywords: Cancer; Exercise; Functional capacity; Prognosis; Risk stratification; Survival.