Is the COPD Assessment Test sensitive for differentiating COPD patients from active smokers and nonsmokers without lung function impairment? A population-based study

Objective: To assess COPD Assessment Test (CAT) scores in adults with and without COPD, as well as to compare the CAT scores for nonsmokers, former smokers, and smokers without COPD with those for patients with COPD. Methods: This was a cross-sectional population-based study (the Respira Floripa study). The study included adults >= 40 years of age residing in the city of Florianopolis, Brazil. A total of 846 households were surveyed. In addition to completing the Respira Floripa questionnaire and the CAT, participants underwent pulmonary function testing. Results: We analyzed data on 1,057 participants (88.1% of the predicted sample size). A functional diagnosis of COPD was made in 92 participants (8.7%). Of those, 72% were unaware that they had COPD. The mean CAT score was higher in the group of COPD patients than in that of individuals without COPD (10.6 [95% CI: 8.8-12.4] vs. 6.6 [95% CI: 6.1-7.0]; p < 0.01). Individual item scores were significantly higher in the patients with COPD than in the individuals without COPD (p < 0.001), the exception being the scores for the items related to sleep (p = 0.13) and energy (p = 0.08). The mean CAT score was higher in the group of COPD patients than in nonsmokers (5.8 [95% CI: 5.3-6.4]) and former smokers (6.4 [95% CI: 5.6-7.2]; p < 0.05). However, there were no significant differences in the mean CAT score between the group of COPD patients and smokers without COPD (9.5 [95% CI: 8.2-10.8]; p > 0.05), the exception being the mean scores for confidence leaving home (p = 0.02). Conclusions: CAT scores were higher in the group of patients with COPD than in nonsmokers and former smokers without COPD. However, there were no significant differences in CAT scores between COPD patients and smokers without COPD. Smokers with an FEV1/FVC ratio > 0.70 have impaired health status and respiratory symptoms similar to those observed in COPD patients.