Table 8.

AUC, sensitivity, specificity, and Youden’s index for five scales.

Name	WOMAC	Pain	Stiffness	Functionality	QOLS
AUC	0.71	0.75	0.68	0.69	0.68
Sensitivity	0.83	0.57	0.89	0.83	0.47
Specificity	0.70	0.80	0.50	0.60	0.86
Youden’s Index	0.53	0.37	0.39	0.43	0.32

If the AUC > 0.7, the estimation is useful.