Reduced Total Airway Count and Airway Wall Tapering after Three-Years in Ex-Smokers.

Computed tomography (CT) total-airway-count (TAC) and airway wall-thickness differ across chronic obstructive pulmonary disease (COPD) severities, but longitudinal insights are lacking. The aim of this study was to evaluate longitudinal CT airway measurements over three-years in ex-smokers. In this prospective convenience sample study, ex-smokers with ( n  = 50; 13 female; age = 70 ± 9 years; pack-years = 43 ± 26) and without ( n  = 40; 17 female; age = 69 ± 10 years; pack-years = 31 ± 17) COPD completed CT, ³ He magnetic resonance imaging (MRI), and pulmonary function tests at baseline and three-year follow-up. CT TAC, airway wall-area (WA), lumen-area (LA), and wall-area percent (WA%) were generated. Emphysema was quantified as the relative-area-of-the-lung with attenuation < -950 Hounsfield-units (RA ₉₅₀ ). MRI ventilation-defect-percent (VDP) was also quantified. Differences over time were evaluated using paired-samples t tests. Multivariable prediction models using the backwards approach were generated. After three-years, forced-expiratory-volume in 1-second (FEV ₁ ) was not different in ex-smokers with ( p  = 0.4) and without ( p  = 0.5) COPD, whereas RA ₉₅₀ was ( p  < 0.001, p  = 0.02, respectively). In ex-smokers without COPD, there was no change in TAC ( p  = 0.2); however, LA ( p  = 0.009) and WA% ( p  = 0.01) were significantly different. In ex-smokers with COPD, TAC ( p  < 0.001), WA ( p  = 0.04), LA ( p  < 0.001), and WA% ( p  < 0.001) were significantly different. In all ex-smokers, TAC was related to VDP (baseline: ρ = -0.30, p  = 0.005; follow-up: ρ = -0.33, p  = 0.002). In significant multivariable models, baseline airway wall-thickness was predictive of TAC worsening. After three-years, in the absence of FEV ₁ worsening, TAC diminished only in ex-smokers with COPD and airway walls were thinner in all ex-smokers. These longitudinal findings suggest that the evaluation of CT airway remodeling may be a useful clinical tool for predicting disease progression and managing COPD. Clinical trial registration: www.clinicaltrials.gov NCT02279329.