The COPD Assessment Test (CAT): short- and medium-term response to pulmonary rehabilitation.

Background: The COPD Assessment Test (CAT) is a recently introduced instrument to assess health-related quality of life in COPD. We aimed to evaluate the longitudinal change in CAT following Pulmonary Rehabilitation (PR), and test the relationship between CAT and CRQ-Self Report (SR) over time. We hypothesised that the CAT would show similar responsiveness to PR as the CRQ-SR both in the short and medium-term.
Methods: 118 COPD patients completed an eight-week outpatient multidisciplinary PR programme. CAT, CRQ-SR and the incremental shuttle walk (ISW) were measured prior to starting PR (T1), completion of PR (T2) and 6 months after completion of PR (T3).
Results: There was a significant improvement in CAT, CRQ-SR and ISW immediately following PR (p < 0.001). Although there was decline between T2 and T3, CAT, CRQ-SR and ISW remained significantly better at T3 compared with T1 (ANOVA p < 0.001). Both between T1-T2 and between T2-T3, change in CAT correlated significantly with change in CRQ (both r = -0.44 and p < 0.001). The slope of the relationship between CAT change and CRQ-SR change at T1-T2 and T2-T3 was not significantly different (ANCOVA: intercept p = 0.79, interaction effect p = 0.95).
Conclusions: In COPD, the CAT score is immediately responsive to PR and remains improved at 6 months. There is no significant difference in the short and medium term changes in the CAT and CRQ-SR following PR. We propose that for most clinical indications for assessing health-related quality of life in COPD, the CAT is a robust and practical alternative to longer-established instruments such as the CRQ-SR.