Change in individual chronic obstructive pulmonary disease assessment test item scores after short-term bronchodilator therapy and its impact on exacerbation in treatment-naive patients with chronic obstructive pulmonary disease

Background: The chronic obstructive pulmonary disease (COPD) assessment test (CAT) measures the health status of patients with COPD. We aimed to investigate the change in individual CAT scores after short-term bronchodilator therapy among treatment-naive patients with COPD. Methods: Data from 148 patients newly diagnosed with COPD between January 2016 and April 2020 were retrospectively analyzed. We compared the CAT score, modified Medical Research Council (mMRC) dyspnea grade, and forced expiratory volume in 1 s (FEV1) before and after short-term (6 +/- 2 months) bronchodilator therapy. We analyzed the change trends using generalized estimating equations. Results: The mean patient age was 70.9 years, and 92.6% were male. The total CAT score did not significantly improve. However, among the CAT items, phlegm [adjusted difference: -0.22 (-0.48, -0.002)], chest tightness [-0.30 (-0.56, -0.05)], and breathlessness [-0.45 (-0.66, -0.23)] scores significantly improved after bronchodilator therapy. The patients were divided into two groups: CAT score improved (n = 69) and not improved group (n = 79). The development of moderate-to-severe exacerbations during follow-up was significantly lower (2.9% versus 17.7%, p = 0.004) in the CAT score improved group. Conclusion: The improvement in CAT items indicating respiratory symptoms was more evident than the CAT total score after short-term bronchodilator therapy. Despite the significant increase in FEV1 after bronchodilator therapy, fewer than half of the patients achieved meaningful improvement in CAT, and this group showed significantly lower development of exacerbation during follow-up.