Fig. 3

ROC curve analysis of sensitivity and specificity of the composite score of combing Aβ seeding activity and APOE ε4 status. To evaluate the performance of the composite score to distinguish AD patients from non-AD individuals, we plotted the true positive rate (sensitivity) in function of the false positive rate (specificity) for different cut-off points. The performance of the test, estimated as the area under the curve was 0.86 (95% confidence interval [CI]: 0.80–0.92; sensitivity: 81.2%, specificity: 80.0%, positive predictive value: 78.9%, negative predictive value:82.2%) and 0.85 (95% CI: 0.78–0.92; sensitivity: 81.2%, specificity: 75.8%, positive predictive value: 78.9%, negative predictive value:78.3%) when AD compared with NC or NADD, respectively. AD, Alzheimer’s disease; Aβ, β-amyloid; ROC, receiver operating characteristic; NADD, non-AD dementia; NC, cognitively normal