Structural features in chronic cough assessed by computed tomography (CT)

Rationale: Features of airway remodelling in terms of bronchial airway wall thickening as well as emphysema have been reported in individuals with chronic cough. The aims of this study were to evaluate chronic cough prevalence and CT-assessed structural features of chronic cough within a general population. Methods: From CanCOLD, a Canadian multi-center, population-based study, 1183 participants aged ≥40 years were included: 286 never-smokers with normal lung function, 297 ever-smokers with normal lung function at risk for COPD, and 600 with moderate to severe COPD (n = 361 GOLD I, n = 239 GOLD II-IV). All performed thoracic CT scans. Imaging parameters analysed comprised of total airway count (TAC), airway wall thickness (WT), emphysema (LAA950= percentage of the lung with low attenuation areas below -950 Hounsfield units) as well as parameters for functional small airway disease (SAD) quantification (PRM=parametric response mapping and DPM=disease probability measure). Chronic cough was defined as cough on most days for at least 3 months in two consecutive years. Results: The prevalence of chronic cough was 7.6% in never smokers and significantly higher in up to 27% in the moderate-severe COPD group (II-IV). In individuals with chronic cough, independently of the presence of COPD, there were no significant differences in CT structural airway (TAC, WT, SAD) or emphysema measurements (LAA950) compared to the no chronic cough control group. Conclusion: Our data indicate that individuals with chronic cough seem to have no specific structural CT features.