Patients' self-reports of dyspnea: An important and independent outcome in chronic obstructive pulmonary disease.

Patients'' self-reports of dyspnea are an important clinical outcome in evaluating treatments in chronic obstructive pulmonary disease (COPD). This study evaluated the dimensions underlying self-reported dyspnea ratings, lung function, and respiratory muscle pressures in 143 patients with COPD. The validity of dyspnea ratings and lung function parameters to predict the variance of a common functional measure, the six-minute walk test, was also assessed. Results of a factor analysis confirmed previous work demonstrating the independence of dyspnea ratings from pulmonary function parameters. Dyspnea ratings also explained a greater proportion of the variance in the six-minute walk test than did lung function. Results of this study provide further evidence for the importance and independence of self-reported dyspnea ratings in evaluating outcomes in COPD.