Impact of chronic cough in individuals with COPD: a population-based cohort study

The role and impact of chronic cough in individuals with chronic obstructive pulmonary disease (COPD) has not been described in the general population. We hypothesised that comorbid chronic cough is a marker of disease severity in individuals with COPD. We identified individuals with COPD and chronic cough among 14,740 adults from the Copenhagen General Population Study and recorded respiratory symptoms, healthcare utilisations, lung function, and systemic and allergic inflammatory biomarkers in blood as outcomes. Among 14,740 individuals, 2296 (16%) suffered from COPD, of whom 141 (6%) had chronic cough. Individuals with COPD and chronic cough had a Leicester Cough Questionnaire median total score of 17.7 (25th and 75th percentiles:16.1-19.0), corresponding to 5.9 (5.3-6.3) for physical domain, 5.6 (4.9-6.3) for psychological domain, and 6.3 (5.8-6.8) for social domain. In individuals with COPD, those with chronic cough versus those without had more often sputum production (53% versus 9%), wheezing (49% versus 16%), dyspnoea (61% versus 36%), night-time dyspnoea (6% versus 2%), acute bronchitis/pneumonia, and general practitioner visits. Furthermore, these individuals had lower FEV1 predicted (80% versus 87%) and FEV1/FVC (0.63 versus 0.66), and had higher levels of high-sensitive C-reactive protein, fibrinogen, leukocytes, neutrophils, and eosinophils in blood. Comorbid chronic cough in individuals with COPD is associated with a more severe disease in terms of more accompanying respiratory symptoms and healthcare utilisations, lower lung function, and increased inflammation in blood.