Table 1. Summary of patient demographics.
| Variables | All | Benign nodule | Primary lung cancer | Metastatic lung cancer | ||||
|---|---|---|---|---|---|---|---|---|
| Mean | SD | Mean | SD | Mean | SD | Mean | SD | |
| N | 1236 | 412 | 571 | 253 | ||||
| Age (y) | 65.76 | 12.65 | 64.81 | 13.80 | 68.41 | 9.70 | 61.35 | 14.97 |
| Sex (number of men) | 709 | 237 | 331 | 141 | ||||
| Smoking history (Brinkman Index) | 605.1 | 774.2 | 543.8 | 747.7 | 756.4 | 841.1 | 354.0 | 543.3 |
| Smoking status | ||||||||
| Current smoker | 266 | 70 | 151 | 45 | ||||
| Ex-smoker | 456 | 161 | 219 | 76 | ||||
| Never smoker | 514 | 181 | 201 | 132 | ||||
| Previous history of malignant tumor | 545 | 148 | 144 | 253 | ||||
| Nodule size (mm) | 20.52 | 10.22 | 18.28 | 8.54 | 24.81 | 10.89 | 14.48 | 6.16 |
| Contrast-enhanced CT | 531 | 113 | 287 | 131 | ||||
Because Brinkman index was not clearly described in 20 patients, Mean and SD of brinkman index were calculated without these 20 patients. Abbreviation: SD, standard deviation; CT, computed tomography.