Table 2. Diagnostic performance of the 2020 C-TIRADS, the 2017 ACR-TIRADS and the 2015 ATA guidelines.

Parameter	C-TIRADS	ACR-TIRADS	ATA guidelines	P value
				C-TIRADS vs. ACR-TIRADS	ACR-TIRADS vs. ATA guidelines	C-TIRADS vs. ATA guidelines
AUROC (95% CI)	0.933 (0.916, 0.949)	0.938 (0.921, 0.955)	0.928 (0.911, 0.945)	0.24	0.02	0.32
Sensitivity (%)	89.38	91.10	88.01	0.49	0.22	0.60
Specificity (%)	89.42	88.68	93.38	0.60	<0.001	0.002
PPV (%)	72.50	71.51	80.56	0.76	0.006	0.01
NPV (%)	96.43	96.96	96.15	0.54	0.35	0.76
Accuracy (%)	89.41	89.25	92.10	0.90	0.02	0.02

The AUROC: χ²=6.02, P=0.0492; the cutoff value of C-TIRADS =1.5 points; the cutoff value of ACR-TIRADS =5.5 points; the cutoff value of ATA =4.5 points. C-TIRADS, Chinese Thyroid Imaging Reporting and Data System; ACR-TIRADS, Thyroid Imaging Reporting and Data System of the American College of Radiology; ATA guidelines, American Thyroid Association guidelines; AUROC, area under the receiver operating characteristic curve; PPV, positive predictive value; NPV, negative predictive value; CI, confidence interval.