Correlation of Luminal Mucus Score in Large Airways with Lung Function and Quality of Life in Severe Acute Exacerbation of COPD: A Cross-Sectional Study

Background and Objective: Luminal mucus plugging in small airways is associated with lung function decline and death of patients with chronic obstructive pulmonary disease (COPD). However, little attention has been paid to the possible role of mucus in large airways in acute exacerbation of COPD (AECOPD). Therefore, this study aimed to explore the relationship between the luminal mucus score of large airways and other physiological parameters of severe AECOPD. Subjects and Methods: A total of 74 AECOPD inpatients were enrolled in this cross-sectional study. All patients underwent lung function tests and bronchoscopy, and their luminal mucus was observed and scored through bronchoscopy. Four questionnaires, including the St. George Respiratory Questionnaire (SGRQ), modified Medical Research Council dyspnea scale (mMRC), COPD Assessment Test (CAT) and Exacerbation of Chronic pulmonary disease Tool (EXACT), were used to assess health-related quality of life (HRQoL). Results: The luminal mucus score of large airways was significantly correlated with spirometry parameters and HRQoL score. Both mMRC grade and SGRQ score were significantly positively correlated with luminal mucus score (rho=0.527, P<0.001; rho=0.441, P<0.001, respectively). Forced expiratory flow at 25% to 75% of the FVC (FEF25%-75%) and FEV1% predicted, as functional measures reflecting small airway disease, were significantly negatively correlated with luminal mucus score (rho=-0.518, P<0.001; rho=-0.498, P<0.001, respectively). The stepwise multiple linear regression model suggested that mMRC grade and FEV1% predicted could predict luminal mucus score (R-2=0.348, F=18.960, P<0.001). Conclusion: For severe acute exacerbation of COPD, bronchoscopy-identified luminal mucus in large airways is associated with reduced lung function and worse health-related quality of life.