LATE-BREAKING ABSTRACT: A large airway phenotype among symptomatic smokers with preserved pulmonary function: The subpopulations and intermediate outcome measures in COPD study (SPIROMICS)

Background: Respiratory symptoms are common among smokers with preserved pulmonary function, but quantitative emphysema is lacking. Aim: To assess large airway morphometry by computed tomography (CT) among symptomatic smokers with preserved pulmonary function, and with COPD. Method: SPIROMICS recruited 2736 participants 40-80 years of age who were smokers with ≥20 pack-years, or non-smokers. Symptom status was defined by a COPD Assessment Test (CAT) score ≥10. Preserved pulmonary function was defined as a post-bronchodilator FEV1/FVC ratio≥0.70, and FVC above the lower limit of normal. COPD status and severity were defined according to guidelines. Airway wall and lumen areas were quantified from generation 0 (trachea) to 4 on full-lung CT (VIDA). Airway percent wall area (%WA) was calculated as wall area/(wall+lumen area)*100. The results include smokers with completed airway measures to date. Results: Among smokers with preserved pulmonary function (n=427), the presence of symptoms (47%) was associated with higher large airway %WA when compared to those without symptoms . Among smokers with mild-to-moderate COPD (n=536), %WA did not differ significantly by symptom status. Conclusion: Symptomatic smokers with preserved pulmonary function have thick large airway walls relative to total airway area, a distinct phenotype when compared to smokers with COPD.