Impact of Test Instructions on 6-min Walk Distance in Adults With Chronic Respiratory Disease

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Abstract
Purpose: The 6-min walk test (6MWT) is commonly used to assess functional exercise capacity in people with chronic respiratory disease in both clinical and research settings. However, two tests are required to achieve accurate results, due to a well-documented learning effect for the 6-min walk distance (6MWD). Whether it is possible to reduce or eliminate the learning effect by optimizing 6MWT instructions is not known. Methods: People with chronic respiratory disease referred to pulmonary rehabilitation undertook two 6MWT with random allocation to modified instructions (fast—walk as fast as possible; n = 46) or usual instructions (far—walk as far as possible; n = 49). The primary outcome was the learning effect, defined as the difference in the 6MWD between test one and test two. Subgroup analyses investigated whether effects varied in those who were naïve to the 6MWT or according to diagnosis (chronic obstructive pulmonary disease, interstitial lung disease, and bronchiectasis). Results: A learning effect was present in both groups, with a mean improvement in the 6MWD on the second test of 14 m in the fast (modified) group (95% CI, 6-22) and 11 m in the far (usual) group (95% CI, 4-19). There was no statistically or clinically significant difference between groups in the magnitude of the learning effect (between-group difference −3 m, 95% CI, −14 to 8). There was no significant effect of naivety to the 6MWT or diagnosis. Conclusion: The current recommended procedures for the 6MWT, including standardized instructions and performance of two tests on each occasion, should be retained.

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