Small Airways Disease and Emphysema (Assessed by High-Resolution CT) and Symptom Burden in COPD

Abstract

<b>Background:</b> Small airways disease (SAD) and emphysema contribute to symptom burden in COPD. In this study, we sought to examine the prevalence of SAD and emphysema in a cohort of COPD patients and to investigate associations with lower and upper airway symptoms. In asthma, SAD and upper airways symptoms are associated. <b>Methods:</b> We examined patients from the BREATHE cohort with High-Resolution CT (HRCT) and subsequent Parametric Response Mapping (PRM) analysis and recorded distribution of emphysema (Emp_PRM) and functional Small Airways Disease (fSAD_PRM). We evaluated upper and lower airway symptoms using the Upper Airway subdomain of the 22 items Sino Nasal Outcome Test (SNOT22_UAS, cut-off ≥ 6 points) and the COPD Assessment Test (CAT), respectively. Dynamic and static lung function tests were measured. <b>Findings:</b> Sixty patients were enrolled (female sex: 52%, age: 67 (±8.3) years, FEV1%predicted: 50.3% (±17.8%), GOLD stage: A: 16%, B: 53%, D: 30%). 22 patients (36%) reported significant upper airway symptoms. The mean levels of Emp_PRM and fSAD_PRM were 25.1% (±13.3%) and 39.5% (±5.2%) respectively. We found no significant association between HRCT scores (Emp_PRM or fSAD_PRM) and symptom burden (CAT score or SNOT22_UAS), despite both HRCT scores correlating significantly and positively with hyperinflation (Residual Volume and Total Lung Capacity) and negatively with FEV1 and diffusion capacity. <b>Conclusion:</b> Functional small airways disease and emphysema are widespread features of COPD, but in the current study not clearly associated with symptom burden.