Chronic cough as a novel phenotype of chronic obstructive pulmonary disease

• Published in: International journal of chronic obstructive pulmonary disease Vol. 13; pp. 1793 - 1801
• Main Authors: Koo, Hyeon-Kyoung, Park, Sung-Woo, Park, Jeong-Woong, Choi, Hye Sook, Kim, Tae-Hyung, Yoon, Hyoung Kyu, Yoo, Kwang Ha, Jung, Ki-Suck, Kim, Deog Kyeom
• Format: Journal Article
• Language: English
• Published: New Zealand Dove Medical Press Limited 01.01.2018; Dove Medical Press Ltd; Dove Medical Press
• Subjects: Abbreviations; Aged; Body mass index; Bronchitis; Bronchitis, Chronic - complications; Bronchitis, Chronic - physiopathology; Carbon monoxide; Chronic Disease; chronic obstructive; Chronic obstructive lung disease; Chronic obstructive pulmonary disease; Cohort Studies; Comparative analysis; cough; Cough - complications; Cough - physiopathology; Councils; Disease Progression; Dyspnea; Dyspnea - complications; Dyspnea - physiopathology; exacerbation; Forced Expiratory Volume; Genetic aspects; Genotype & phenotype; Hemoglobin; Humans; Lung diseases; Lungs; Male; Medical research; Multivariate Analysis; Original Research; Patients; Phenotype; pulmonary disease; Pulmonary Disease, Chronic Obstructive - complications; Pulmonary Disease, Chronic Obstructive - physiopathology; Quality of Life; Questionnaires; Republic of Korea; Respiratory tract diseases; Risk factors; severity; Spirometry; Sputum; Republic of Korea; severity; chronic obstructive; pulmonary disease; cough; exacerbation
• ISSN: 1178-2005; 1176-9106; 1178-2005
• DOI: 10.2147/COPD.S153821

Chronic cough can be a dominant symptom of chronic obstructive pulmonary disease (COPD), although its clinical impact remains unclear. The aim of our study was to identify phenotypic differences according to the presence of chronic cough or sputum and evaluate the impact of chronic cough on the risk of acute exacerbation of COPD (AECOPD). In a nationwide COPD cohort including 1,613 COPD patients, patients with chronic cough only, those with sputum only, those with chronic bronchitis (CB), and those without cough and sputum were compared with regard to dyspnea, lung function, quality of life (QoL), and risk of AECOPD. The rates of chronic cough, chronic sputum, and both were 23.4%, 32.4%, and 18.2%, respectively. Compared with patients without chronic cough, those with chronic cough exhibited a lower forced expiratory volume in 1 second (% predicted) and diffusing capacity of the lungs for carbon monoxide (% predicted), more frequent AECOPD, more severe dyspnea, and worse QoL. Pulmonary function, dyspnea severity, and QoL worsened in the following order: without cough or sputum, with sputum only, with cough only, and with CB. Multivariate analyses revealed chronic cough as an independent risk factor for a lower lung function, more severe dyspnea, and a poor QoL. Moreover, the risk of future AECOPD was significantly associated with chronic cough (odds ratio 1.56, 95% CI 1.08-2.24), but not with chronic sputum. Our results suggest that chronic cough should be considered as an important phenotype during the determination of high-risk groups of COPD patients.