However, the mean increase in 6MWD achieved by both groups was small and might be regarded as of borderline clinical significance. Although the direction of change is consistent with an updated systematic review 5 and other randomized controlled studies,8,9 it does not approach the previously reported MCID of 54 m (95% confidence interval [CI] 37–71 m). 32 On the other hand, our results do approach the more recently reported MCID of 25 m (95% CI 20–61 m),45 and others have also reported an MCID of 26±2 m in people with severe COPD following PR.46 Such small improvement may have particular relevance for severe COPD, and in our study, half of the participants were severely affected in this way. The 20 m change we observed is also within the lower limit of the CI observed by Holland et al. 45