Fig. 4

ROC curves indicating the discriminating ability of sAPPα (a), sAPPβ (b), and p-tau (c) in MCI-AD versus other groups (AD, MCI-O, non-AD, and disease control). For sAPPα, area under the curve (AUC) = 0.729 [Asymptotic 95% Confidence Interval: 0.584–0.873] and the appropriate cut off value is sAPPα = 250, with sensitivity = 0.765 and specificity = 0.544. For sAPPβ, AUC = 0.730 [0.589–0.872] and the appropriate cut off value is sAPPβ = 586, with sensitivity = 0.824 and specificity = 0.595. For p-tau, AUC = 0.745 [0.631–0.858] and the appropriate cut off value is p-tau = 66, with sensitivity = 0.824 and specificity = 0.641. (d) ROC curve for the combination of sAPPβ and sAPPα. AUC = 0.747 [0.605–0.889]