The relationship between airway thickness and persistent eosinophilia in COPD

<bold>Background:</bold> Chronic obstructive pulmonary disease (COPD) is characterized by irreversible airflow obstruction. Blood eosinophil count (BEC) has been associated with responsiveness to inhaled corticosteroids. We hypothesised that persistent eosinophilia is associated with radiological evidence of airway thickness. <bold>Methods:</bold> Participants were recruited from the London COPD Exacerbation Cohort. BEC was assessed yearly in stable conditions for 4 years (4 visits). Exacerbation data was collected before oral corticosteroid treatment. Patients were classified by eosinophilic status (Fig 1). All participants underwent inspiratory and expiratory quantitative Computed Tomography analysed for an index of airway lumen to wall thickness (Pi10), degree of emphysema, air trapping and Ground Glass using VIDA software. <bold>Results:</bold> 100 patients were included in our analysis. Pi10 was significantly higher in the Persistent Eosinophilic group compared to the Never and Intermittent groups (Fig 1), while no differences were identified in terms of air trapping, emphysema and Ground Glass. Pi10 in the Eosinophilic Exacerbators was not different from the Non Eosinophilic Exacerbators (Fig 1). <bold>Conclusion:</bold> Persistent eosinophilia is associated with an increased wall thickness to lumen relationship. Further studies are needed to establish whether targeting eosinophilic airway inflammation can modify airway thickness, with clinical implications for COPD patients. <fig><object-id>erj;64/suppl_68/PA3965/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>