Table 1.
Baseline demographic and clinical characteristics of the patients
| Variable | Training set, n = 1257 | Validation set, n = 173 | P value |
|---|---|---|---|
| Age (year) | |||
| Mean ± SD | 60.6 ± 9.7 | 61.3 ± 8.9 | 0.365 |
| Median (IQR) | 61 (55–68) | 62 (56.5–68) | |
| Gender | |||
| Female | 582 (46.3%) | 77 (44.5%) | |
| Male | 675 (53.7%) | 96 (55.5%) | 0.658 |
| Health insurance | |||
| Yes | 408 (32.5%) | 54 (31.2%) | |
| No | 849 (67.5%) | 119 (68.8%) | 0.743 |
| Smoking status | |||
| Never or ever | 986 (78.4%) | 126 (72.8%) | |
| Current | 271 (21.6%) | 47 (27.2%) | 0.096 |
| Respiratory symptoms | |||
| No | 784 (62.4%) | 114 (65.9%) | |
| Yes | 473 (37.6%) | 59 (34.1%) | 0.368 |
| FEV1 (L) | |||
| Mean ± SD | 2.34 ± 0.60 | 2.30 ± 0.66 | 0.458 |
| Median (IQR) | 2.29 (1.93–2.71) | 2.21 (1.79–2.70) | |
| FEV1 % predicted (%) | |||
| Mean ± SD | 89.1 ± 18.5 | 86.9 ± 17.9 | 0.143 |
| Median (IQR) | 89.4 (77.1–101.2) | 87.1 (74.6–101.3) | |
| FVC (L) | |||
| Mean ± SD | 3.04 ± 0.74 | 3.02 ± 0.83 | 0.764 |
| Median (IQR) | 2.94 (2.52–3.51) | 2.91 (2.38–3.59) | |
| FVC % predicted (%) | |||
| Mean ± SD | 91.1 ± 14.9 | 89.1 ± 15.6 | 0.108 |
| Median (IQR) | 90.7 (81.2–100.4) | 88.6 (78.3–100.3) | |
| FEV1/FVC < 70% (COPD) | |||
| No | 1026 (81.6%) | 138 (79.8%) | |
| Yes | 231 (18.4%) | 35 (20.2%) | 0.557 |
| RV/TLC (%) | |||
| Mean ± SD | 37.7 ± 7.8 | 38.1 ± 7.7 | 0.481 |
| Median (IQR) | 37.5 (33.3–42.6) | 38.5 (34.2–43.1) | |
| DLCO | |||
| Mean ± SD | 18.3 ± 5.3 | 18.0 ± 5.1 | 0.492 |
| Median (IQR) | 18.3 (15.2–21.6) | 17.8 (15.2–20.5) | |
| Surgical approach | |||
| VATS | 832 (66.2%) | 139 (80.3%) | |
| Open | 425 (33.8%) | 34 (19.7%) | < 0.001* |
| Surgical type | |||
| Sub-lobectomy | 147 (11.7%) | 30 (17.3%) | |
| Lobectomy | 1085 (86.3%) | 142 (82.1%) | |
| Pneumonectomy | 25 (2.0%) | 1 (0.6%) | 0.052 |
| p-LOS (day) | |||
| Mean ± SD | 6.8 ± 2.5 | 6.1 ± 2.8 | 0.002* |
| Median (IQR) | 6 (5–7) | 5 (5–7) | < 0.001* |
| Normal (≤ 7 days) | 947 (75.3%) | 146 (84.4%) | |
| Prolonged (> 7 days) | 310 (24.7%) | 27 (15.6%) | 0.009* |
SD standard deviation, IQR interquartile range, FEV1 forced expiratory volume in one second, FVC forced vital capacity, COPD chronic obstructive pulmonary disease, RV/TLC ratio of residual volume to total lung capacity, DLCO diffusion capacity for carbon monoxide, VATS video-assisted thoracic surgery, p-LOS postoperative length of stay
*Statistically significant