Chronic Cough in Individuals With COPD: A Population-Based Cohort Study

Abstract

Background: The role and impact of chronic cough in individuals with COPD have not been described in the general population. This study hypothesized that comorbid chronic cough is a marker of disease severity in individuals with COPD. Methods: This study identified individuals with COPD and chronic cough, and recorded respiratory symptoms, health-care utilizations, lung function, and inflammatory biomarkers in blood in a nested cohort of 43,271 adults from the Copenhagen General Population Study (CGPS). Results: Among 43,271 individuals from the general population, 8,181 (19%) experienced COPD, of whom 796 (10%) had chronic cough. Individuals with COPD and chronic cough had a Leicester Cough Questionnaire median (25th-75th percentiles) total score of 17.7 (16.0-18.9), corresponding to 5.9 (5.3-6.3) for the physical domain, 5.6 (4.9-6.3) for the psychological domain, and 6.3 (5.8-6.8) for the social domain. Among individuals with COPD, those with chronic cough vs those without chronic cough more often experienced sputum production (60% vs 8%), wheezing (46% vs 14%), dyspnea (66% vs 38%), chest pain/tightness (9% vs 4%), nighttime dyspnea (8% vs 3%), episodes of acute bronchitis/pneumonias in the last 10 years (45% vs 25%), and ≥ 3 general practitioner visits in the past 12 months (53% vs 37%). Furthermore, these individuals had lower FEV1 % predicted (81% vs 89%) and FEV1/FVC (0.64 vs 0.66), as well as higher levels of high-sensitivity C-reactive protein, fibrinogen, leukocytes, neutrophils, eosinophils, and IgE in blood. Conclusions: Comorbid chronic cough in individuals with COPD is associated with a more severe disease in terms of more respiratory symptoms and health-care utilizations, lower lung function, and increased inflammation in blood.