COPD exacerbations and patient-reported outcomes according to post-bronchodilator FEV1 – a post-hoc analysis of pooled data

Abstract

Abstract Background Management strategies of chronic obstructive pulmonary disease (COPD) need to be tailored to the forced expiratory volume in one second (FEV1), exacerbations, and patient-reported outcomes (PROs) of individual patients. In this study, we analyzed the association and correlation between the FEV1, exacerbations, and PROs of patients with stable COPD. Methods This was a post-hoc analysis of pooled data from two cross-sectional studies that were previously conducted in Malaysia from 2017 to 2019, the results of which had been published separately. The parameters measured included post-bronchodilator FEV1 (PB-FEV1), exacerbations, and scores of modified Medical Research Council (mMRC), COPD Assessment Test (CAT), and St George’s Respiratory Questionnaire for COPD (SGRQ-c). Descriptive, association, and correlation statistics were used. Results Three hundred seventy-four patients were included in the analysis. The PB-FEV1 predicted was < 30% in 85 (22.7%), 30–49% in 142 (38.0%), 50–79% in 111 (29.7%), and ≥ 80% in 36 (9.6%) patients. Patients with PB-FEV1 < 30% predicted had significantly more COPD exacerbations than those with PB-FEV1 30–49% predicted (p < 0.001), 50–79% predicted (p < 0.001), and ≥ 80% predicted (p = 0.002). The scores of mMRC, CAT, and SGRQ-c were not significantly higher in patients with more severe airflow limitation based on PB-FEV1 (p = 0.121–0.271). The PB-FEV1 predicted had significant weak negative correlations with exacerbations (r = − 0.182, p < 0.001), mMRC (r = − 0.121, p = 0.020), and SGRQ-c scores (r = − 0.114, p = 0.028). There was a moderate positive correlation between COPD exacerbations and scores of mMRC, CAT, and SGRQ-c (r = 0.407–0.482, all p < 0.001). There were significant strong positive correlations between mMRC score with CAT (r = 0.727) and SGRQ-c scores (r = 0.847), and CAT score with SGRQ-c score (r = 0.851) (all p < 0.001). Conclusions In COPD patients, different severity of airflow limitation was not associated with significant differences in the mMRC, CAT, and SGRQ-c scores. Exacerbations were significantly more frequent in patients with very severe airflow limitation only. The correlation between airflow limitation with exacerbations, mMRC, and SGRQ-c was weak.