A comparative study of airway Optical coherence tomography to assess airway morphology in patients with asthma, COPD, and ACO

<bold>Title:</bold> A comparative study of airway Optical coherence tomography to assess airway morphology in patients with asthma, COPD, and ACO <bold>Objective:</bold> To compare the difference of airway structure in asthma, COPD and ACO. <bold>Methods:</bold> Airway wall thickness (Aw%) and lumen area (Ai/BSA, corrected by BSA) were measured by endobronchial optical coherence tomography (EB-OCT) in 86 asthmatic, 122 COPD, and 36 asthma-COPD overlap (ACO) patients, respectively. The clinical features, chest CT and lung function examination data of enrolled patients were collected and analyzed. <bold>Results:</bold> There was no statistically significant difference in gender, BMI and BSA among all groups (P>0.05). Clinically, most patients with COPD are elderly, while asthmatic patients have an earlier onset age. The degree of large airway stenosis in ACO group was significantly higher than that in COPD group (Ai/BSA3-6: 5.59±2.26 v.s. 8.39±2.90, P<0.001) and asthma group (Ai/BSA7-9: 5.59±2.26 v.s. 7.08±2.68, P=0.048). The remodeling degree of large airway in ACO group was higher than that in COPD group (Aw% 3-6:41.22±11.93v.s. 33.29±7.30, P=0.021; Aw%7-9: 53.92±2.78 v.s.47.19±8.34, P>0.05) and asthma group (Aw%3-6: 41.22±11.93v.s. 34.27±9.55, P>0.05; Aw%7-9: 53.92±2.78 v.s.51.32±9.37, P>0.05). <bold>Conclusion:</bold> The remodeling degree of ACO is significantly higher than that of simple asthma and COPD, which is manifested by airway stenosis and wall thickening. EB-OCT imaging may be useful for disease differentiation and early diagnosis.