Functional exercise capacity
Twenty two trials including 890 participants (458 actively treated
and 432 controls) were available. Limiting the meta-analysis to
the 16 trials (346 actively treated, 323 controls) that used the sixminute
walk test as an outcome, the common effect (weighted
mean difference) was 48 metres (95% CI: 32 to 65); homogeneity:
P = 0.16. Our estimate of the MCID of the walk test, about 50
metres, comes from a study in which COPD participants rated
their walking ability through subjective comparisons with one another
(Redelmeier 1997). Since the inferior limit of the confidence
interval around the common effect (32 to 65 meters) lies beyond
the limit of the confidence interval around the estimate of the
MCID for the six-minute walk test (CI: 37 to 71 meters), the
clinical significance of the result obtained from the meta-analysis
remains uncertain