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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