Exercise Duration during a Brief Step Test Independently Predicts Outcomes after Hematopoietic Cell Transplantation

Area of Science:

• Hematopoietic Cell Transplantation (HCT)
• Pulmonary Medicine
• Exercise Physiology

Background:

• Pre-transplant pulmonary function testing (PFT) is standard for hematopoietic cell transplantation (HCT) recipients.
• Objective functional capacity assessment is not routinely performed alongside PFTs.
• A 3-minute step exercise test provides measures of exercise duration and oxygen desaturation.

Purpose of the Study:

• To determine if step test variables (exercise duration, oxygen desaturation) add prognostic value to a baseline model for HCT outcomes.
• To evaluate the predictive ability of step test variables for overall survival, ICU admission, and invasive mechanical ventilation within 120 days post-HCT.

Main Methods:

• Retrospective cohort study of 3,458 adult HCT recipients undergoing a 3-minute step test.
• Analysis included Cox regression for overall survival and logistic regression for ICU admission and mechanical ventilation.
• Additive value of exercise variables was assessed against a baseline model including age, sex, transplant type, FEV1 z-score, DLCO z-score, and hemoglobin.

Main Results:

• Exercise duration independently predicted overall survival, ICU admission, and invasive mechanical ventilation.
• Each additional minute of exercise was associated with significantly lower mortality, ICU admission, and mechanical ventilation odds.
• Oxygen desaturation did not predict any outcome after adjustment for hemoglobin, indicating confounding.

Conclusions:

• Exercise duration from a brief pre-transplant step test is a valuable independent predictor of HCT outcomes.
• This measure captures pre-transplant fitness beyond traditional PFTs and hemoglobin levels.
• Routine assessment of exercise capacity before HCT is recommended.