Patient Characteristics and Ultrasonographic Appearance of Thyroid Nodules at All Investigation Sites
| Characteristic | Total | Site 1 | Site 2 | Site 3 | Test | P |
| Patients | 582 (100) | 145 (24.9) | 300 (51.5) | 137 (23.6) | χ2 | 0.0002 |
| Female | 442 (75.9) | 115 (79.3) | 246 (82.0) | 81 (59.1) | ||
| Male | 140 (24.1) | 30 (20.7) | 54 (18.0) | 56 (40.9) | ||
| Mean age (y) | 58.3 ± 13.1 | 55.4 ± 13.4 | 57.5 ± 13.4 | 62.9 ± 10.8 | ANOVA | 0.0002 |
| Female | 57.7 ± 13.2 | 55.8 ± 13.7 | 57.1 ± 13.3 | 62.3 ± 11.0 | 0.0231 | |
| Male | 60.1 ± 12.7 | 54.1 ± 12.4 | 59.6 ± 13.7 | 63.7 ± 10.6 | 0.0426 | |
| Nodules | 615 (100) | 145 (23.6) | 317 (51.5) | 153 (24.9) | — | — |
| Median largest diameter (mm) | 23.2 ± 10.0 | 22.4 ± 8.7 | 21.8 ± 9.2 | 27.3 ± 11.6 | ANOVA | 0.0002 |
| Patients with hyperthyroidism | 117 (20.1) | 21 (14.5) | 56 (18.7) | 40 (29.2) | χ2 | 1.0000 |
| Resected nodules | 42 (6.8) | 30 (20.7) | 10 (3.2) | 2 (1.3) | χ2 | <0.0001 |
| Ultrasound features | ||||||
| Solid composition | 348 (56.6) | 77 (53.1) | 190 (59.9) | 81 (52.9) | χ2 | 1.0000 |
| Hypoechogenicity | 311 (50.6) | 67 (46.2) | 169 (53.3) | 75 (49.0) | χ2 | 1.0000 |
| Marked hypoechogenicity | 34 (5.5) | 9 (6.2) | 15 (4.7) | 10 (6.5) | χ2 | 1.0000 |
| Calcification | 263 (42.8) | 43 (29.7) | 151 (47.6) | 69 (45.1) | χ2 | 0.0168 |
| Microcalcification | 209 (34.0) | 31 (21.4) | 130 (41.0) | 48 (31.4) | χ2 | 0.0021 |
| Irregular margins | 117 (19.0) | 33 (22.8) | 58 (18.3) | 26 (17.0) | χ2 | 1.0000 |
| Lobulated margins | 62 (10.1) | 17 (11.7) | 31 (9.8) | 14 (9.2) | χ2 | 1.0000 |
| Ill-defined margins | 55 (8.9) | 16 (11.0) | 27 (8.5) | 12 (7.8) | χ2 | 1.0000 |
| Taller than wide shape | 66 (10.7) | 21 (14.5) | 35 (11.0) | 10 (6.5) | χ2 | 1.0000 |
Qualitative data are expressed as numbers followed by percentages in parentheses; continuous data are expressed as mean or median ± SD.