Table 3. Difference test of malignancy rates of the three subcategories.
| Group | ACR TIRADS (points) | Total (N) | Malignant, n (%) | χ² | P |
|---|---|---|---|---|---|
| Group 1 | 4–5 | 71 | 17 (23.9) | 2.292 | 0.13 |
| 6 | 40 | 15 (37.5) | |||
| Group 2 | 6 | 40 | 15 (37.5) | 7.521 | 0.006* |
| 7–8 | 68 | 44 (64.7) | |||
| Group 3 | 4–5 | 71 | 17 (23.9) | 24.141 | ＜0.001* |
| 6 | 40 | 15 (37.5) | |||
| 7–8 | 68 | 44 (64.7) | |||
| Group 4 | 7–8 | 68 | 44 (64.7) | 11.144 | 0.001* |
| ≥9 | 177 | 149 (84.2) |
P value reflects the differences of the three subcategories. *P<0.05 were considered as significant difference. ACR, American College of Radiology; TIRADS, Thyroid Imaging Reporting and Data System.