Longitudinal study of airway dimensions in chronic obstructive pulmonary disease using computed tomography

Background and objective: Chest CT has been widely used for the evaluation of structural changes in lung parenchyma and airways in cross‐sectional studies. There has been no report on the annual changes in airway dimensions as assessed by CT in COPD patients. The objective of this study was to investigate the annual changes in airway dimensions and lung attenuation using CT in patients with COPD and to evaluate the correlations among annual changes in CT measurements and pulmonary function. Methods: Eighty‐three men with COPD had completed five annual assessments of CT scans and pulmonary function tests over 4 years. Airway dimensions of the basal segment bronchi and lung attenuation on CT images were analysed in 38 subjects in whom the same airway could be measured at least three times, including at entry and at the end of the study. Results: Mean annual decline in FEV 1 was 21 mL/year. Annual changes in the percentage of low attenuation areas were not significantly correlated with decline in FEV 1 . On the other hand, annual changes in the percentage of wall area (WA%/year) were significantly inversely correlated with annual changes in FEV 1 ( r = −0.363, P = 0.025), whereas WA%/year did not differ among severity stages at entry and did not correlate with baseline FEV 1 . Conclusions: The results showing that annual changes in airway thickening correlated with annual decline in air flow limitation suggests the importance of treatment of airway inflammation in COPD. CT is a useful tool for quantitative estimation not only of emphysema but also of airway lesions in longitudinal studies.