Incidental findings on chest CT imaging are associated with increased COPD exacerbations and mortality

Abstract

Background: This study aimed to evaluate whether incidental CT findings of emphysema, airway thickening and bronchiectasis, as seen on CT scans performed for other non-pulmonary clinical indications, are associated with future acute exacerbations of COPD resulting in hospitalisation or death.

Methods: This multicentre prospective case-cohort study comprised 6406 subjects who underwent routine diagnostic chest CT for non-pulmonary indications. Using a case-cohort approach, we visually graded CT scans from cases and a random sample of ∼10% of the baseline cohort (n=704) for emphysema severity (range 0-20), airway thickening (range 0-5) and bronchiectasis (range 0-5). We used weighted Cox proportional hazards analysis to assess the independent association between CT findings and hospitalisation or death due to COPD exacerbation.

Results: During a median follow-up of 4.4 years (maximum 5.2 years), 338 COPD events were identified. The risk of experiencing a future acute exacerbation of COPD resulting in hospitalisation or death was significantly increased in subjects with severe emphysema (score ≥7) and severe airway thickening (score ≥3). The respective HRs were 4.6 (95% CI 3.0 to 7.1) and 5.9 (95% CI 3.4 to 10.5). Severe bronchiectasis (score ≥3) was not significantly associated with increased risk of adverse events (HR 1.5; 95% CI 0.9 to 2.5).

Conclusions: Morphological correlates of COPD such as emphysema and airway thickening detected on CT scans obtained for other non-pulmonary indications are strong independent predictors of subsequent development of acute exacerbations of COPD resulting in hospitalisation or death.

Keywords: Bronchiectasis; COPD Exacerbations; COPD epidemiology; Clinical Epidemiology; Emphysema; Imaging/CT MRI etc.