Table 1. Differences of demographics and characteristics for M0 patients of PTMC in different data sets.
| Demographics and characteristics | Training data (n=15124) | Internal testing data (n=6482) | External testing data (n=1031) | Total (n=22637) |
| Age (year) | ||||
| <55 | 9388 (62.07) | 4081 (62.96) | 807 (78.27) | 14276 (63.06) |
| ≥55 | 5736 (37.93) | 2401 (37.04) | 224 (21.73) | 8361 (36.94) |
| Race | ||||
| Other1 | 1524 (10.08) | 655 (10.10) | 1031 | 3210 (14.18) |
| white | 12503 (82.67) | 5391 (83.17) | / | 17894 (79.05) |
| black | 1097 (7.25) | 436 (6.73) | / | 1533 (6.77) |
| Sex | ||||
| Male | 2666 (17.63) | 1145 (17.66) | 186 (18.04) | 3997 (17.66) |
| Female | 12458 (82.37) | 5337 (82.34) | 845 (81.96) | 18640 (82.34) |
| Tumor size (mm) | 5.51±2.94 | 5.51±2.97 | 5.50±2.41 | 5.51±2.93 |
| Extension | ||||
| intrathyroidal extension | 14194 (93.85) | 6081 (93.81) | 967 (93.80) | 21242 (93.84) |
| minimal extension | 868 (5.74) | 375 (5.79) | 52 (5.04) | 1295 (5.72) |
| gross extension | 62 (0.41) | 26 (0.40) | 12 (1.16) | 100 (0.44) |
| Multifocality | ||||
| Solitary tumor | 9684 (64.03) | 4173 (64.38) | 803 (77.89) | 14660 (64.76) |
| Multifocal tumor | 5440 (35.97) | 2309 (35.62) | 228 (22.11) | 7977 (35.24) |
| N status | ||||
| positive | 1812 (11.98) | 771 (11.89) | 367 (35.60) | 2950 (13.03) |
| negative | 13312 (88.02) | 5711 (88.11) | 664 (64.40) | 19687 (86.97) |
Notes: All data was presented as the number of cases and composition ratio (%) or mean ± standard deviation. 1Including American Indian/AK Native, Asian/Pacific Islander.
Abbreviations: M0 = no distant metastases; PTMC = papillary thyroid microcarcinoma.