Airway resistance correlates with the frequency of exacerbation in patient with COPD

Background: Many studies have reported that increasing rate of airflow limitation is correlated with frequency of exacerbation. Whereas the relationship between peripheral airway resistance and frequency of exacerbation in COPD has not yet been investigated. Aim: The aim of this study was to evaluate the airway resistance and reactance measured by forced oscillometry, and to correlate these with frequency of exacerbation in COPD patients. Methods: 310 patients with COPD (GOLD stage I to IV) who attended our outpatient clinic from September 2014 through January 2015 were selected. 110 patients fulfilled our criteria. We divided the patients into two groups. The 1st group was exacerbator group and the 2nd group was non-exacerbator group. The frequency of exacerbations, airway resistance and reactance were evaluated retrospectively on the basis of our database. Results: There were significant differences in expiratory and inspiratory resistance between the exacerbator group and non-exacerbator group. Differences in both expiratory and inspiratory were found at 20 Hz (R20), reactance at 5 Hz (X5), resonant frequency (Fres) and low-frequency reactance area (ALX). Difference in only inspiratory resistance was found in differences between R5 and R20 (R5-R20). Conclusion: Airway resistance and reactance shown by X5, Fres and ALX may be useful to predict the risk of exacerbation in COPD patients.