Minimum important difference of the incremental shuttle walk test distance in patients with COPD.

We aimed to describe the minimum important difference (MID) of the ISWT in patients with COPD using both distribution- and anchor-based methods. Two cohorts were used (n=613) with eligibility criteria of a clinical diagnosis of COPD, an FEV1/FVC<70%, and an ISWT (after familiarisation) before and after a seven week course of pulmonary rehabilitation (PR). The MID of the ISWT using the distribution method was 36.1m. The area under the curve to discriminate between perceived ‘improvement’ or ‘no improvement’ post-PR for a change in ISWT of 35m was 0.66 [0.58–0.73]. The MID of the ISWT is therefore between 35.0-36.1m.