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Table 5 Regression models for lung function, exercise capacity and symptoms in all subjects

From: Paired inspiratory-expiratory chest CT scans to assess for small airways disease in COPD

A. Linear regression for FEV1 (L)
  Exp−856 E/I MLA RVC856-950
Independent variables β* p-value β* p-value β* p-value
% emphysema (Insp−950) −0.11 < 0.0001 −0.31 < 0.0001 −0.29 < 0.0001
Gas Trapping variable† −0.45 < 0.0001 −0.30 < 0.0001 −0.30 < 0.0001
Model fit statistics
R2 0.67 0.68 0.68
B. Linear regression for FEV1/FVC
  Exp−856 E/I MLA RVC856-950
Independent variables β* p-value β* p-value β* p-value
% emphysema (Insp−950) −0.03 < 0.0001 −0.09 < 0.0001 −0.10 < 0.0001
Gas Trapping variable† −0.10 < 0.0001 −0.06 < 0.0001 −0.03 < 0.0001
Model fit statistics
R2 0.73 0.70 0.64
C. Linear regression for FEF25-75
  Exp−856 E/I MLA RVC856-950
Independent variables β* p-value β* p-value β* p-value
% emphysema (Insp−950) 0.0002 0.99 −0.29 < 0.0001 −0.38 < 0.0001
Gas Trapping variable† −0.68 < 0.0001 −0.51 < 0.0001 −0.24 < 0.0001
Model fit statistics
R2 0.50 0.52 0.45
D. Linear regression for 6-minute walk distance (ft).
  Exp−856 E/I MLA RVC856-950
Independent variables β* p-value β* p-value β* p-value
% emphysema (Insp−950) −47.8 < 0.0001 −46.3 < 0.0001 −37.3 < 0.0001
Gas Trapping variable† −3.7 0.6 −22.0 < 0.0001 −51.8 < 0.0001
Model fit statistics
R2 0.44 0.44 0.45
E. Linear regression for SGRQ Total score.
  Exp−856 E/I MLA RVC856-950
Independent variables β* p-value β* p-value β* p-value
% emphysema (Insp−950) 1.3 0.0004 2.8 < 0.0001 2.7 < 0.0001
Gas Trapping variable† 3.2 < 0.0001 1.9 < 0.0001 1.7 < 0.0001
Model fit statistics
R2 0.42 0.42 0.42
  1. All models are adjusted for age, sex, race, clinical center, current smoking status, pack-years of smoking, height, weight, Siemens 64 scanner. Models for 6-minute walk distance (D) and SGRQ score (E) were additionally adjusted for FEV1% predicted.
  2. *Independent variables standardized to mean = 0 and SD = 1. β = change in dependent variable, e.g. FEV1 (L), for each SD change in independent variable.
  3. †Either Exp−856, E/I mean lung attenuation ratio, or RVC856-950.