Emerging concepts in outcome assessment for COPD clinical trials.

The selection of appropriate, clinically meaningful outcome measures for chronic obstructive pulmonary disease (COPD) clinical trials is a complex issue. Functional exercise measures are more likely to adequately reflect the effect of novel and emerging interventions than traditional physiological measures such as forced expiratory volume in 1 second (FEV (1)). Nonetheless, among several exercise measures commonly used, the choice is not a simple issue and should be based upon rational as well as pragmatic issues. This is because important measurement properties (validity and responsiveness) can differ among exercise measures, among different interventions, and across degrees of disability. Furthermore, "free-living" daily activity measures may be more meaningful measures than these "in-lab" exercise measures for future clinical trials of COPD, although their reproducibility, validity, and responsiveness have not yet been adequately studied. Application of these and other emerging concepts in outcome assessment for COPD clinical trials will be examined.