The COPD Assessment Test (CAT) was validated in English showing good psychometric properties. The objective of this study is to assess the capacity of the CAT to detect changes in health status in patients experiencing COPD exacerbations (ECOPD) and to further explore the validity of the Spanish version. An observational study was conducted in 49 Spanish centres. Patients hospitalised because of ECOPD (n = 224) completed the CAT, the St. George's Respiratory Questionnaire-adapted for COPD (SGRQ-C) and the London Chest Activities of Daily Living (LCADL) questionnaire during the first 48 hours of admission and 4 ± 1 weeks after discharge. Stable patients (n = 153) also completed these at recruitment and 4 ± 1 weeks later. Over 90% of patients were male. The CAT discriminated between stable and ECOPD patients (15.8 vs 22.4, p < 0.01), as well as between patients with different levels of airflow limitation and dyspnea (MRC scale). The CAT proved sensitive to change; change in mean score was 8.9 points (effect size (ES), 0.90) in ECOPD patients reporting their health state as "much better" after discharge, 4.8 points in those reporting "quite a lot better" (ES = 0.63), and 4.6 points in those reporting "slightly better" (ES = 0.59). Cronbach's alpha and Intraclass Correlation Coefficient were 0.86 and 0.83, respectively. It correlated with both the SGRQ (r = 0.82; p < 0.01) and the LCADL (r = 0.63; p < 0.01). Change in CAT correlated well with Δ SGRQ (r = 0.63; p < 0.01). The CAT showed to be sensitive to the change in health status associated with ECOPD. We also provide evidence of the validity of the Spanish version.
