Table 1.
Characteristics of Study Subjects
| Variable | Nonsmokers | Smokers Without COPD | COPD Stages 1-2 |
COPD Stages 3-4 |
|---|---|---|---|---|
| No. (M/F) | 12 (3/9) | 19 (11/8) | 13 (10/3) | 13 (11/2) |
| Age, y | 65.3 ± 11.1 | 58.9 ± 12.3 | 64.6 ± 10.1 | 64.2 ± 11.1 |
| Pack-years | 0 | 38.9 ± 25.3 | 70.9 ± 27.2a | 68.1 ± 25.8a |
| Emphysema | 1 of 12 | 6 of 19 | 12 of 13 | 13 of 13 |
| Emphysema score | 0.29 ± 1.01 | 0.39 ± 0.74 | 1.33 ± 1.17 | 2.25 ± 1.20a,b |
| MRC dyspnea score | 0.33 ± 0.89 | 0.68 ± 0.95 | 1.46 ± 0.78c | 2.38 ± 1.12a,b |
| Charlson index | 0.58 ± 1.00 | 0.95 ± 1.08 | 1.54 ± 1.27 | 1.92 ± 1.12c |
| Pao2 (mm Hg) | 81.2 ± 7.2 | 77.7 ± 5.8 | 73.6 ± 6.9 | 66.7 ± 9.0a,b |
| Paco2 (mm Hg) | 38.3 ± 2.4 | 39.5 ± 1.7 | 39.6 ± 2.7 | 39.8 ± 7.4 |
| Pao2/Fio2 (mm Hg/%) | 386.7 ± 34.4 | 370.2 ± 27.8 | 350.5 ± 33.0 | 307.7 ± 55.5a,b |
| Aado2 | 20.6 ± 9.4 | 22.6 ± 6.3 | 25.4 ± 7.2 | 41.0 ± 23.1a,b |
| Pao2/Paco2 | 2.12 ± 0.15 | 1.97 ± 0.17 | 1.82 ± 0.19b | 1.72 ± 0.33b,d |
| BMI (kg/m2) | 25.8 ± 3.2 | 29.0 ± 7.5 | 24.8 ± 3.6 | 23.0 ± 3.5d |
| FEV1 % predicted (%) | 89.4 ± 12.6 | 89.7 ± 14.4 | 73.1 ± 14.6a,c | 32.2 ± 7.8a,b |
| FVC % predicted (%) | 84.2 ± 11.3 | 87.2 ± 14.9 | 90.3 ± 18.9 | 57.2 ± 11.7a,b |
| FEV1/FVC | 84.4 ± 5.6 | 81.8 ± 9.2 | 61.4 ± 7.2a,b | 45.9 ± 7.8a,b |
| Dlco % predicted (%) | 78.9 ± 19.7 | 77.3 ± 17.3 | 63.5 ± 20.8 | 43.0 ± 13.7a,b |
| KCO % predicted (%) | 85.1 ± 16.9 | 89.2 ± 10.9 | 67.8 ± 19.5a | 59.9 ± 14.0a,b |
| TLC % predicted (%) | 83.7 ± 9.4 | 86.0 ± 25.6 | 94.6 ± 13.4 | 102.7 ± 36.2 |
| FRC % predicted (%) | 81.7 ± 8.3 | 82.2 ± 24.6 | 106.0 ± 27.1 | 110.3 ± 25.6c,d |
| RV % predicted (%) | 82.8 ± 8.6 | 80.2 ± 20.7 | 107.9 ± 23.9a,c | 120.6 ± 18.5a,b |
| RV/TLC | 0.365 ± 0.062 | 0.324 ± 0.075 | 0.401 ± 0.085 | 0.473 ± 0.085a,b |
| IC % predicted (%) | 84.8 ± 10.1 | 86.6 ± 23.8 | 85.5 ± 16.3 | 56.7 ± 16.5a,b |
| 6MWD (m) | 480.2 ± 110.2 | 508.6 ± 108.5 | 439.2 ± 122.4 | 359.6 ± 147.4a |
| DBOrgDyspnea | 0.92 ± 2.27 | 0.68 ± 1.70 | 2.00 ± 1.73 | 3.15 ± 1.91a,c |
| DBorgFatigue | 0.92 ± 1.68 | 0.68 ± 1.11 | 1.23 ± 1.17 | 2.38 ± 1.66a |
| Dsat (%) | –1.2 ± 4.4 | –0.7 ± 3.2 | –2.5 ± 4.6 | –7.2 ± 4.7a,b |
| DHR | 30.6 ± 8.3 | 21.3 ± 9.5 | 32.5 ± 23.1 | 22.3 ± 15.4 |
| LABA/ LAMA/ ICS | 1/ 1/ 0 | 2/ 2/ 3 | 8/ 9/ 3 | 10/ 10/ 10 |
| CVD/ DM | 2/ 2 | 7/ 2 | 6/ 1 | 5/ 3 |
Data are expressed as mean values ± SD. Pack-year represents the number of cigarettes smoked per day/20 × duration of smoking in years. Patients with COPD were categorized by the Global Initiative for Chronic Obstructive Lung Disease definition guidelines.22 Emphysematous phenotype was characterized according to the presence of significant emphysematous lesions (> 15% of lung parenchyma) by high-resolution CT.31 Patients with COPD were characterized as having frequent exacerbations if there were two or more exacerbations in 1 year.33
6MWD = six-min walking distance; Aado2 = alveolar-arterial oxygen difference; CVD = cardiovascular disease; DHR = difference in heart rate during 6MWD; DBorgDyspnea = the difference in Dyspnea level according to Borg scale between the end and the beginning of the 6-min walk test; DBorgFatigue = the difference in Fatigue level according to Borg scale between the end and the beginning of the 6-min walk test; Dlco = diffusing capacity of lung for carbon monoxide; Dsat = Desaturation on movement; DM = diabetes mellitus; FRC = functional residual capacity; IC = inspiratory capacity; ICS = inhaled corticosteroids; KCO = the carbon monoxide transfer coefficient; LABA = long acting beta-agonists; LAMA = long-acting muscarinic antagonists; MRC = Medical Research Council; RV = residual volume; TLC = total lung capacity.
P < .01 vs smokers without COPD.
P < .01 vs nonsmokers.
P < .05 vs nonsmokers.
P < .05 vs smokers without COPD.