The 4-metre gait speed in COPD: responsiveness and minimal clinically important difference

Area of Science:

• Pulmonary Medicine
• Geriatrics
• Rehabilitation Science

Background:

• Usual gait speed predicts adverse outcomes in older adults.
• Four-meter gait speed (4MGS) is validated in chronic obstructive pulmonary disease (COPD).
• Responsiveness and minimal clinically important difference (MCID) of 4MGS in COPD require assessment.

Purpose of the Study:

• Assess the responsiveness of 4MGS in COPD patients.
• Estimate the MCID for 4MGS in COPD.
• Evaluate 4MGS as a functional assessment tool in COPD.

Main Methods:

• 301 COPD patients: 4MGS and incremental shuttle walk (ISW) measured pre/post pulmonary rehabilitation.
• 162 COPD patients: 4MGS and ISW measured at baseline and 1-year follow-up.
• MCID estimated using distribution and anchor-based methods (ISW, self-reported improvement).

Main Results:

• 4MGS significantly improved post-pulmonary rehabilitation (mean change 0.08 m·s⁻¹, p<0.001).
• MCID estimates for 4MGS ranged from 0.08 to 0.11 m·s⁻¹.
• 4MGS showed greater effect size in frail individuals and declined over 12 months (-0.04 m·s⁻¹).

Conclusions:

• 4MGS is responsive to pulmonary rehabilitation and longitudinal changes in COPD.
• 4MGS demonstrates potential as a simple functional assessment tool for COPD.
• 4MGS may be particularly valuable for assessing frail individuals with COPD.