title: Relative contributions of emphysema and airway remodelling to airflow limitation in COPD: Consistent results from two cohorts.
abstract: OBJECTIVE
  The relative contributions of emphysema and airway remodelling to airflow limitation remain unclear in chronic obstructive pulmonary disease (COPD). We aimed to evaluate the relative contributions of emphysema and airway wall thickness measured by quantitative computed tomography (CT) to the prediction of airflow limitation in two separate COPD cohorts.
  
  
  METHODS
  Pulmonary function tests and whole-lung CT were performed in 250 male smokers with COPD, including 167 from University Medical Center at Ho Chi Minh City, Vietnam, and 83 from Shiga University of Medical Science Hospital, Japan. The same CT analysis software was used to measure the percentage of low attenuation volume (%LAV) at the threshold of -950 Hounsfield units and the square root of wall area of a hypothetical airway with an internal perimeter of 10 mm (Pi10). The standardized coefficients in multiple linear regressions were used to evaluate the relative contributions of %LAV and Pi10 to predictions of FEV1 /FVC and FEV1 % predicted.
  
  
  RESULTS
  Both %LAV and Pi10 independently predicted either forced expiratory volume in 1 s/forced vital capacity (FEV1 /FVC) or FEV1 % predicted (P ≤ 0.001 for all standardized coefficients). However, the absolute values of the standardized coefficients were 2-3 times higher for %LAV than for Pi10 in all prediction models. The results were consistent in the two COPD cohorts.
  
  
  CONCLUSIONS
  %LAV predicts both FEV1 /FVC and FEV1 better than Pi10 in patients with COPD. Thus, emphysema may make a greater contribution to airflow limitation than airway remodelling in COPD.
authors: Division of Respiratory Medicine, Department of Medicine, Shiga University of Medical Science, Shiga, Japan; Respiratory Care Center, University Medical Center, Ho Chi Minh City, Vietnam.
authors: Nguyen Van
authors: NV
authors: Tho
authors: Yasushi
authors: Y
authors: Ryujin
authors: Emiko
authors: E
authors: Ogawa
authors: Le Thi Huyen
authors: le TH
authors: Trang
authors: Rie
authors: R
authors: Kanda
authors: Kenichi
authors: K
authors: Goto
authors: Masafumi
authors: M
authors: Yamaguchi
authors: Taishi
authors: T
authors: Nagao
authors: Le Thi Tuyet
authors: le TT
authors: Lan
authors: Yasutaka
authors: Y
authors: Nakano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D056151:Airway Remodeling; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005541:Forced Expiratory Volume; D006801:Humans; D007564:Japan; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012129:Respiratory Function Tests; D012907:Smoking / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D014744:Vietnam; D014797:Vital Capacity
keywords: airway remodelling; chronic obstructive pulmonary disease; computed tomography; emphysema; quantitative imaging