Introduction: The 6-min-walk test is widely used for functional evaluation of patients with chronic obstructive pulmonary disease (COPD), but the test requires a 30-m unobstructed hallway, which is not available in all institutions. A treadmill 6-min walk test might be more practical.
Methods: In a crossover study, we compared the results from hallway and treadmill 6-min-walk tests by 19 patients with moderate to very severe COPD. Each patient did 3 hallway tests and 3 treadmill tests. The hallway tests were according to the American Thoracic Society guidelines.
Results: The mean hallway walk distance was significantly (102 m, 95% confidence interval 65-139 m) greater than the mean treadmill walk distance. Between the hallway and treadmill tests, agreement was very poor via Bland-Altman analysis, correlation was low (r = 0.48, P = .04), and those differences were not explained by differences in patient effort. The differences between the 3 treadmill tests were greater than those between the 3 hallway tests, and in both the hallway and treadmill tests patient effort progressively diminished, indicating a learning effect.
Conclusions: The hallway and treadmill walk tests are not interchangeable. We need further study and standardization of the treadmill 6-min walk test.