Inter-assay diagnostic accuracy of cerebrospinal fluid kappa free light chains for the diagnosis of multiple sclerosis

• DOI: 10.3389/fimmu.2024.1385231
• Publication Date: 2024-04-30T05:07:26Z
• Authors: Cathérine Dekeyser; Pieter De Kesel; Melissa Cambron; Ludo Vanopdenbosch; Liesbeth Van Hijfte; Martine Vercammen; Guy Laureys
• Keywords: Cut-off; Kappa; Roche Diagnostics

Background Cerebrospinal fluid (CSF) kappa free light chain (κFLC) measures gained increasing interest as diagnostic markers in multiple sclerosis (MS). However, the lack of studies comparing assay-dependent cutoff values hinders their use clinical practice. Additionally, optimal κFLC parameter for identifying MS remains a subject ongoing debate. Objectives The aim this study was to compare same-sample accuracies index, κIgG CSF κFLC/IgG ratio, and isolated (iCSF-κFLC) between two reference centers using different methods. Methods Paired serum samples were analyzed albumin concentrations by Freelite ® -Optilite (Sint-Jan Bruges hospital) N Latex -BNII (Ghent University hospital). Diagnostic performance differentiate from controls assessed ROC curve analysis. Results A total 263 participants included (MS, n = 80). Optimal index (Freelite -Optilite: 7.7; -BNII: 4.71), 14.15, 12.19), ratio 2.27; 1.44) differed Sensitivities related 89.9% -Optilite) versus 94.6% (N -BNII) 91% 92.2% 81.3% 91.4% ratio. iCSF-κFLC, (0.36 mg/L) specificities (81.8%) identical with sensitivity 90.5% -BNII. [area under (AUC) 0.924; 0.962] (AUC 0.929; 0.961) superior compared oligoclonal bands (AUC: 0.898, sensitivity: 83.8%, specificity: 95.9%). Conclusions seem be excellent MS, irrespective method used quantification. Based on AUC, they appear choice. For all measures, methods except iCSF-κFLC. iCSF-κFLC might therefore serve method-independent, more cost-efficient, initial screening measure MS. These findings are particularly relevant practice given potential future implementation intrathecal synthesis criteria multicentre pooling data measures.