When patients with COPD experience changes in health status while recovering from exacerbations or undergoing pulmonary rehabilitation, these changes are likely to be reflected by the COPD Assessment Test (CAT). Paul W. Jones, PhD, of St. George’s University, London, and colleagues reported this conclusion in the July Chest. They investigated the CAT’s responsiveness to health status changes in two studies with separate cohorts.
The CAT includes items related to coughing, mucus production, chest tightness, capacity for exercise and activities, confidence, sleep quality, and energy levels. Each item is scored from 0 (best) to 5 (worst), and the test’s overall scale ranges from 0 to 40.
Study 1 assessed the CAT’s responsiveness in a cohort of 67 COPD patients undergoing recovery from exacerbations. The patients completed the CAT and other tests at their baseline visit and at a second visit 14 days later. During the second visit, the clinician and patient independently completed ratings of change in COPD since baseline, with patients defined as responders when they had a global change rating of “better,” “much better,” or “completely resolved.”
Patient-rated global responses were significantly correlated with CAT score changes. The mean change in CAT score was -2.8 units in patient-judged responders and 0.0 in patient-judged nonresponders; this difference was statistically significant. Physician-judged responders and nonresponders had mean CAT changes of -2.6 units and -0.2 units, respectively, but this difference was not statistically significant.
Study 2 assessed the CAT’s responsiveness in a cohort of 64 patients with stable COPD who were referred for six weeks of pulmonary rehabilitation. In addition to the CAT, these patients completed the Chronic Respiratory Questionnaire—Self Administered Standardized (CRQ-SAS), the six-minute walk test, the Borg scale for breathlessness, and other tests at their baseline visit. The tests were repeated during their second visit, which took place a mean of 42 days later.
The patients’ mean improvement in CAT score was -2.2, and the effect size for the change was -0.33. There was a significant correlation between CAT score changes and changes in CRQ-SAS domain scores. Correlations between CAT score changes and changes in Borg scores and six-minute walk distance were nonsignificant, however.
“The CAT is a short, reliable, and valid tool for monitoring COPD health status over time,” the authors concluded. “It can quantify COPD health status gain with rehabilitation and is responsive to recovery from an exacerbation.”
Jones PW, Harding G, Wiklund I, et al. Tests of the responsiveness of the COPD Assessment Test following acute exacerbation and pulmonary rehabilitation. Chest. 2012,142(1):134-140.