S100B and Creutzfeldt Jacob disease: Se, Sp, and positive and negative likelihood ratios (LR+, LR-) were estimated for 14-3-3, tau and S100B (Table 1), applying either our estimated optimal thresholds or, for the ELISA assays, consensus thresholds (T1300, S4.2) widely applied by other CJD reference laboratories using the same reagent kits [13].