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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.