Sample size
6MWT is the most commonly used outcome indicator in pulmonary rehabilitation (PR) and can be used for sample size estimation. In 6MWT, the minimum difference (miniDIFF) between different groups is 54 m, and the baseline standard deviation (SD) is 57 m. Given a two-tailed 0.05 and a power of 80%, the minimal sample size for each group is 19. To compensate for the expected loss of participants, an adjusted sample size of 27 could be acquired for each group, and 140 patients could be recruited, assuming a roll-out rate of 30%.