Prevalence of Small-Airway Dysfunction among COPD Patients with Different GOLD Stages and Its Role in the Impact of Disease

Background: In chronic obstructive pulmonary disease (COPD) patients, small-airway dysfunction (SAD) is considered a functional hallmark of disease. However, the exact role of SAD in the clinical presentation of COPD is not yet completely understood; moreover, it is not known whether SAD may have a relationship with the impact of disease. Objectives: To evaluate the prevalence of SAD among COPD patients categorized by the old and the new GOLD classification and to ascertain whether there is a relationship between SAD and impact of disease measured by the COPD Assessment Test (CAT) questionnaire. Methods: We prospectively enrolled COPD outpatients from the University Hospital of Parma. Using the impulse oscillometry system (IOS), we assessed the fall in resistance from 5 to 20 Hz (R5-R20), reactance at 5 Hz (X5), and resonant frequency (F-Res) as markers of peripheral airway dysfunction. According to R5-R20 >= 0.07 or <0.07, the cohort was also categorized in patients with and without SAD, respectively. Results: We studied 202 patients. In both GOLD classifications, a progressive increasing distribution of R5-R20 and F-Res was reported with a decreas-ing of X5. Moreover, there was a significant correlation between R5-R20 and CAT (r = 0.527, p < 0.001). Finally, the presence of SAD (OR 11.96; 95% CI 4.53-31.58; p < 0.001) and use of ICS + LABA + LAMA (OR 5.31; 95% CI 1.88-15.02; p = 0.002) were independent predictors of higher impact (CAT score = 10). Conclusion: In COPD patients, the presence of SAD, as assessed by IOS, progressively increases with GOLD classifications and it is closely related to the high impact of disease on health status. (C) 2016 S. Karger AG, Basel