Longitudinal Computed Tomography Airway Measurements in Ex-Smokers with and without Chronic Obstructive Pulmonary Disease
Abstract
Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease characterized by chronic airflow obstruction, emphysematous destruction, and airway remodeling. Thoracic CT has previously revealed abnormalities in the small airways, where disease onset is believed to initiate. In previous COPD cohort studies, airway wall thinning and diminished total airway count (TAC) were observed with increasing disease severity. However, longitudinal insights are lacking. Accordingly, the objective of this thesis was to evaluate longitudinal CT airway measurements at baseline and after three-years in ex-smokers. I observed that CT TAC was decreased only in ex-smokers with COPD, whilst airway walls were thinner in both ex-smokers with and without COPD. To my knowledge, this is the first study to show TAC worsening over time in COPD, which suggests airway narrowing, obstruction, and/or obliteration. These longitudinal three-year findings in ex-smokers, in whom forced expiratory volume in 1-second did not change, provide insights into mechanisms of COPD progression.