Table 4

Anchor-based estimates of the MID and distribution-based estimates of the MDC for D-PPAC and C-PPAC amount, difficulty and total scores

D-PPACC-PPAC
AmountDifficultyTotalAmountDifficultyTotal
Anchor based
Change in CCQ total*5.72.55.53.3
Change in amount of physical activity†6.25.24.83.7
Change in difficulty with physical activity†5.46.05.75.95.0
Change in physical activity experience overall†4.84.85.84.1
Distribution based
0.5 of Cohen’s effect size6.77.25.37.67.26.0
1 SEM (of ICC)5.45.43.8
  • *Mean difference (final–baseline) in scores in patients who changed ≤−0.4 points in CCQ score.

  • †Mean difference (final–baseline) in scores in patients who rated their physical activity change as ‘better’ in amount, difficulty or overall.

  • CCQ, clinical COPD questionnaire; COPD, chronic obstructive pulmonary disease; C-PPAC, Clinical visit version of PROactive Physical Activity in COPD instrument; D-PPAC, Daily version of PROactive Physical Activity in COPD instrument; ICC, intraclass correlation coefficient ; MDC, minimal detectable change; MID, minimal important difference; SEM, standard error of measurement.