Table 1. Patient Characteristics and CT Parameters.
| Parameter | GOLD | P | |||
|---|---|---|---|---|---|
| I (n = 117) | II (n = 139) | III (n = 98) | IV (n = 16) | ||
| Age, year | 66.9 ± 8.4 | 66.2 ± 7.2 | 67.9 ± 6.8 | 65.4 ± 7.9 | 0.32 |
| BMI, kg/m2 | 23.7 ± 4.3 | 23.0 ± 3.6 | 22.1 ± 3.1 | 19.4 ± 3.8 | < 0.001 |
| Current:ex-smoker | 41:76 | 57:82 | 26:72 | 6:10 | 0.77 |
| Pack-year | 46.7 ± 26.1 | 45.3 ± 25.7 | 44.7 ± 26.2 | 55.7 ± 36.6 | 0.46 |
| FVC, % | 103.5 ± 16.4 | 90.4 ± 13.9 | 80.6 ± 16.2 | 67.8 ± 13.8 | < 0.001 |
| FEV1, % | 81.7 ± 10.7 | 59.8 ± 5.4 | 42.0 ± 5.5 | 26.3 ± 2.4 | < 0.001 |
| FEV1/FVC, % | 56.3 ± 8.1 | 47.5 ± 8.4 | 38.3 ± 8.3 | 28.8 ± 7.2 | < 0.001 |
| DLCO, % | 44.6 ± 47.5 | 58.2 ± 42.3 | 46.2 ± 36.4 | 43.4 ± 27.3 | 0.04 |
| RV, % | 107.1 ± 43.9 | 128.4 ± 49.6 | 162.4 ± 59.5 | 223.7 ± 41.1 | < 0.001 |
| TLC, % | 109.4 ± 20.4 | 108.8 ± 22.0 | 116.9 ± 24.3 | 135.1 ± 17.1 | < 0.001 |
| VC, % | 103.5 ± 22.2 | 91.0 ± 15.9 | 81.9 ± 17.3 | 70.1 ± 15.5 | < 0.001 |
| IC, % | 89.0 ± 18.8 | 76.8 ± 17.1 | 68.4 ± 18.1 | 52.9 ± 14.5 | < 0.001 |
| FRC, % | 117.2 ± 28.2 | 126.2 ± 31.5 | 144.5 ± 37.3 | 179.1 ± 21.7 | < 0.001 |
| 6-min walk test, m | 441.7 ± 89.5 | 441.2 ± 75.2 | 405.4 ± 86.4 | 346.1 ± 88.4 | < 0.001 |
| Initial SpO2 | 96.5 ± 1.9 | 96.7 ± 1.7 | 96.2 ± 1.9 | 95.0 ± 2.8 | 0.004 |
| Post SpO2 after 6-min walk test | 95.1 ± 4.8 | 95.2 ± 3.9 | 93.7 ± 5.0 | 89.2 ± 9.2 | < 0.001 |
| Parenchymal attenuation parameters on CT | |||||
| ATI | 0.92 ± 0.04 | 0.95 ± 0.03 | 0.97 ± 0.02 | 0.98 ± 0.01 | < 0.001 |
| Inspiratory MLD, HU* | -875.6 ± 23.5 | -878.5 ± 26.4 | -888.7 ± 26.8 | -910.4 ± 15.6 | < 0.001 |
| EI, % | 15.5 ± 12.7 | 18.9 ± 13.6 | 27.2 ± 16.0 | 43.3 ± 11.4 | < 0.001 |
| Airway parameters on CT, integral-based half-band method | |||||
| No. of segmented bronchi | 99.2 ± 49.9 | 91.1 ± 42.9 | 79.0 ± 46.2 | 95.6 ± 58.1 | 0.02 |
| Lumen diameter, mm | 3.20 ± 0.41 | 3.08 ± 0.39 | 3.11 ± 0.41 | 3.18 ± 0.37 | 0.09 |
| Wall thickness, mm | 1.17 ± 0.34 | 1.23 ± 0.32 | 1.36 ± 0.42 | 1.26 ± 0.32 | 0.001 |
| WA% | 63.6 ± 9.4 | 66.7 ± 8.1 | 68.9 ± 8.7 | 66.4 ± 6.2 | < 0.001 |
| Pi10, mm | 3.94 ± 0.83 | 4.16 ± 0.78 | 4.41 ± 0.94 | 4.12 ± 0.66 | 0.001 |
*Values were obtained using inspiration CT images. ATI = air-trapping index, BMI = body mass index, CT = computed tomography, DLCO = percentage of predicted diffusing capacity of the lungs for carbon monoxide, EI = emphysema index, FEV1 = percentage predicted forced expiratory volume in one second, FEV1/FVC = ratio of forced expiratory volume in one second to forced vital capacity, FRC = functional residual capacity, FVC = percentage of predicted forced vital capacity, GOLD = Global Initiative for Chronic Obstructive Lung Disease, HU = Hounsfield unit, IC = inspiratory capacity, MLD = mean lung density, Pi10 = square root of wall area of hypothetical airway with internal perimeter of 10 mm, RV = percentage of predicted residual volume, SpO2 = blood oxygen saturation, TLC = total lung capacity, VC = vital capacity, WA% = wall area percentage