Longitudinal airway remodeling in active and past smokers in a lung cancer screening population

ObjectivesTo longitudinally investigate smoking cessation-related changes of quantitative computed tomography (QCT)-based airway metrics in a group of heavy smokers.MethodsCT scans were acquired in a lung cancer screening population over 4years at 12-month intervals in 284 long-term ex-smokers (ES), 405 continuously active smokers (CS), and 31 subjects who quitted smoking within 2years after baseline CT (recent quitters, RQ). Total diameter (TD), lumen area (LA), and wall percentage (WP) of 1st-8th generation airways were computed using airway analysis software. Inter-group comparison was performed using Mann-Whitney U test or Student's t test (two groups), and ANOVA or ANOVA on ranks with Dunn's multiple comparison test (more than two groups), while Fisher's exact test or chi-squared test was used for categorical data. Multiple linear regression was used for multivariable analysis.ResultsAt any time, TD and LA were significantly higher in ES than CS, for example, in 5th-8th generation airways at baseline with 6.24mm vs. 5.93mm (p<0.001) and 15.23mm(2) vs. 13.51mm(2) (p<0.001), respectively. RQ showed higher TD (6.15mm vs. 5.93mm, n.s.) and significantly higher LA (14.77mm(2) vs. 13.51mm(2), p<0.001) than CS after 3years, and after 4years. In multivariate analyses, smoking status independently predicted TD, LA, and WP at baseline, at 3years and 4years (p<0.01-0.001), with stronger impact than pack years.ConclusionsBronchial dimensions depend on the smoking status. Smoking-induced airway remodeling can be partially reversible after smoking cessation even in long-term heavy smokers. Therefore, QCT-based airway metrics in clinical trials should consider the current smoking status besides pack years.Key Points center dot Airway lumen and diameter are decreased in active smokers compared to ex-smokers, and there is a trend towards increased airway wall thickness in active smokers.center dot Smoking-related airway changes improve within 2years after smoking cessation.center dot Smoking status is an independent predictor of airway dimensions.