Purpose: The 6-minute walk test (6MWT) is commonly used to measure exercise capacity in COPD, but it is unclear if this test is accurate when performed at home. This study aimed to determine whether exercise capacity can be accurately assessed at home using the 6MWT in COPD.
Methods: A total of 19 participants with stable COPD (mean [SD] FEV1/FVC 52) undertook the 6MWT at home and at the hospital, in random order, with two tests performed on each occasion. Hospital tests were conducted on a 30-metre walking track whilst home tests (indoor or outdoor) were conducted using the longest available track. Agreement for 6-minute walk distance (6MWD) was examined using the Bland and Altman method.
Results: The track length at home was mean [SD] of 17 m. The home 6MWD was shorter than the hospital 6MWD (mean 30 m shorter, limits of agreement -167 to 102 m). For the home tests, a shorter track length was associated with a greater reduction in 6MWD (rs = 0.59, p = 0.01), but not an increased number of turns (rs = -0.41, p = 0.08).
Conclusions: The 6MWD underestimates exercise capacity when conducted at home in COPD. Alternative tests suitable for the home environment should be considered if a comprehensive assessment is to be performed at home.
Implications for rehabilitation: The 6-minute walk test is commonly used to assess change in exercise capacity following pulmonary rehabilitation in patients with chronic obstructive pulmonary disease, and may be conducted on varying track lengths, indoors or outdoors. When conducted at home, the 6-minute walk test underestimates exercise capacity in chronic obstructive pulmonary disease, due to a shorter track length available in the home environment. This suggests that results from 6-minute walk tests performed at home environment cannot be directly compared to results from centre-based tests.
Keywords: 6MWT; COPD; rehabilitation.