Abstract
INTRODUCTION: Noninvasive evaluation of airway conditions is considered useful in the management of COPD, although assessing airway remodeling remains difficult in routine clinical practice. The impulse oscillometry system used in this study allows separate analysis of inspiratory and expiratory phases, offering detailed insights into airway function. This study examined the effects of inhaled corticosteroids (ICSs) on airway remodeling and assessed the utility of this system in COPD management. METHODS: Stable COPD patients on LAMA/LABA for over a year were assessed by spirometry and impulse oscillometry at baseline and after 48 weeks of ICS/LAMA/LABA therapy. Symptoms, imaging, and blood tests were also evaluated. RESULTS: Among 52 patients (mean baseline %FEV1/predicted: 56.9% ± 22.1%), all had one to two moderate exacerbations in the past year despite LAMA/LABA therapy. Significant correlations were observed between spirometry and MostGraph (e.g., baseline FEV1 vs. R5: r = -0.54). Although spirometry showed no significant changes, Fres improved significantly (-2.11 ± 0.35, p < 0.0001), with reductions in both expiratory and inspiratory phases. CONCLUSIONS: Fres measured by MostGraph significantly improved after ICS addition, whereas no significant changes were observed in spirometry or resistance parameters. Fres also showed significant correlations with FEV1, suggesting that it may capture airway changes not detected by spirometry. These findings support further investigation into its role as a noninvasive marker in COPD. TRIAL REGISTRATION: UMIN-CTR Clinical Trial: UMIN000040764 (https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000042394).