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Table 3 Comparison of CT variables between ever-smokers with normal FEV1 and FEV1/FVC > LLN but < 0.70 (“discordant” group), ever-smokers with normal FEV1 and FEV1/FVC > 0.70, and never-smokers with normal FEV1 and FEV1/FVC > 0.70

From: Heterogeneous burden of lung disease in smokers with borderline airflow obstruction

Variable

Group 1

Ever-smokers, Normal FEV1,

\( \frac{\mathrm{FEV}1}{\mathrm{FVC}} \) < 0.7 and > LLN

(Discordant Group) (n = 161)

Group 2

Ever-smokers, Normal FEV1,

\( \frac{\mathrm{FEV}1}{\mathrm{FVC}} \)>  0.7

(n = 940)

Group 3

Never-smokers, Normal FEV1,

\( \frac{\mathrm{FEV}1}{\mathrm{FVC}} \)>  0.7

(n = 190)

Overall p-value* from likelihood ratio test comparing association with group status

Unadjusted

(Adjusted)

P-values for pairwise comparisons (Unadjusted)

Group 1 vs. 2

Group 1 vs. 3

Group 2 vs. 3

Emphysema (%)

2.1 ± 2.9

0.7 ± 2.6

0.3 ± 0.9

< 0.001

(<  0.001)

<  0.001

<  0.001

<  0.001**

Functional small airways disease (%)

18.0 ± 10.6

9.1 ± 10.0

7.1 ± 8.3

< 0.001

(<  0.001)

<  0.001

<  0.001

<  0.001**

Airway wall thickening (Pi10)

3.70 ± 0.01

3.71 ± 0.00

3.69 ± 0.01

< 0.001

(0.17)

0.41

0.01

< 0.001**

Emphysema present > ULN

38.7%

17.4%

8.2%

< 0.001

(< 0.001)

< 0.001

< 0.001

0.004†

CT-defined functional small airway abnormality (fSAD) present > ULN

15.3%

7.8%

2.9%

< 0.001

(0.03)

0.003

< 0.001

0.03†

Either emphysema or fSAD present

44%

20.7%

9.4%

< 0.001 (< 0.001)

< 0.001

< 0.001

< 0.001†

Both emphysema and fSAD present

10%

4.5%

1.8%

0.002 (0.23)

0.007

0.005

0.11†

  1. Presence of emphysema = ≥ upper limit of normal (ULN); Presence of fSAD = ≥ upper limit of normal (ULN). Emphysema = % of voxels with CT attenuation <− 950 Hounsfield Units (HU) on full inspiration. Functional small airways disease = % of voxels with CT attenuation > − 950 HU on the inspiratory exam and < − 856 HU on the expiratory scan, as determined via dynamic image registration (Parametric Response Mapping, PRM)
  2. *From likelihood ratio test comparing means of 3 groups from multivariable model with outcomes (rows) and group status as predictors adjusted for age, sex, race, smoking history (pack-years) and current smoking
  3. **P-value from 2 sample t test
  4. Pairwise p-value form Wald test comparing means of 2 groups