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Table 2 Comparison of physiologic and clinical 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

Clinical Outcome 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* Unadjusted (Adjusted) P-values for pairwise comparisons (Unadjusted)
Group 1 vs. 2 Group 1 vs. 3 Group 2 vs. 3
FEV1% predicted 92.1 ± 12.0 97.5 ± 12.8 102.0 ± 11.5 <  0.001 (<  0.001) <  0.001 <  0.001 <  0.001**
FEF25–75% % predicted 61.2 ± 11.0 102.3 ± 33.4 121.3 ± 32.5 <  0.001 (<  0.001) <  0.001 <  0.001 <  0.001**
6MWD (m) 437.5 ± 109.6 437.2 ± 97.7 479.3 ± 103.4 <  0.001 (0.49) 0.97 <  0.001 < 0.001**
St George’s Respiratory Questionnaire Total Score 22.5 ± 17.4 24.2 ± 19.1 8.8 ± 10.0 <  0.001 (<  0.001) 0.28 <  0.001 <  0.001**
COPD Assessment Test (CAT) 10.7 ± 7.4 11.3 ± 8.1 4.7 ± 6.0 < 0.001 (<  0.001) 0.36 < 0.001 < 0.001**
Use of either inhaled corticosteroid or bronchodilator 34.4% 25.1% 3.9% < 0.001 (< 0.001) 0.01 < 0.001 < 0.001†
Chronic bronchitis 17.3% 17.8% 2.1% < 0.001 (< 0.001) 0.88 < 0.001 < 0.001†
mMRC Dyspnea score ≥ 2 13.8% 13.6% 2.7% < 0.001 (0.007) 0.95 < 0.001 < 0.001†
Change in FEV1 (ml/year) − 60.5 ± 120.5 −55.2 ± 127.5 −41.2 ± 99.7 0.32
(0.94)
0.64 0.17 0.19**
Exacerbation (#/year) 0.1 ± 0.4 0.1 ± 0.6 0.02 ± 0.1 0.02
(0.21)
0.50 0.13 0.006**
  1. 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). Airway thickening = square root of the wall area for a standardized airway with an internal perimeter of 10 mm (Pi10)
  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-values from 2 sample t-test
  4. Pairwise p-value form Wald test comparing means of 2 groups