title: Prevalence of Small-Airway Dysfunction among COPD Patients with Different GOLD Stages and Its Role in the Impact of Disease.
abstract: 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.
  
  
  OBJECTIVE
  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 (FRes) 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 FRes was reported with a decreasing 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Respiratory Disease and Lung Function Unit, Department of Clinical and Experimental Medicine, University of Parma, Parma, Italy.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Crisafulli
authors.forename: Roberta
authors.initials: R
authors.lastname: Pisi
authors.forename: Marina
authors.initials: M
authors.lastname: Aiello
authors.forename: Matteo
authors.initials: M
authors.lastname: Vigna
authors.forename: Panagiota
authors.initials: P
authors.lastname: Tzani
authors.forename: Anna
authors.initials: A
authors.lastname: Torres
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Bertorelli
authors.forename: Alfredo
authors.initials: A
authors.lastname: Chetta
mesh_terms: D000368:Aged; D055745:Bronchioles / Q000503:physiopathology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000503:physiopathology*; D012720:Severity of Illness Index