Figure 5.

Estimation of intrathecal synthesis. (A) ROC curve for various amounts of ITS and different Q_{A lb} indicating sensitivity (Se) and specificity to discriminate ITS from normal Q_{I gG}. Points from left to right give Se and Sp of IgG index, Q_{L im}(3SD), Q_{L im}(2SD), Q_{L im}(1SD), and Q _mean. All AUC except one (ITS +1 mg/L at Q_{A lb} 10) are significantly different from 0.5. Low amounts of ITS are poorly discriminated by Reibergram except at very low values of Q_{A lb}. For example, AUC of ITS +5 mg/L decreases from 0.954 (0.941–0.966) at Q_{A lb}=2 to 0.667 (0.624–0.710) at Q_{A lb}=10. (B) At single patient level, calculation of IgG_{L oc} remains unreliable, especially based on Q_{L im}. (C) Convergence of the error range (in absolute value) of IgG_{L oc} calculation at a cohort level. Convergence toward the exact ITS value is independent from amount of ITS, but strongly depends from Q_{A lb}. Fewer than 10 patients are required to compensate extreme outliers. Formula is: |mean(IgG_{L oc}_true) – mean(IgG_{L oc} calculated)|. For each condition (Q_{A lb}; ITS), up to 60 subjects are included in 12 independent simulated assays.