To evaluate the diagnostic performance of the κ-FLC index for MS in a real-world series, emphasizing its role in differentiating MS from other inflammatory and non-inflammatory neurological disorders.
Key Findings:
A total of 124 patients were included (49 MS/CIS, 48 OIND, 27 NIND). Median κ-FLC index values were significantly higher in MS/CIS compared with OIND and NIND (p < 0.001). The optimal κ-FLC index cut-off for MS/CIS vs OIND was 14.6, with sensitivity of 73.5% and specificity of 68.1%. A lower threshold of 6.1 showed higher sensitivity (85.7%) but limited specificity (35.4%). Reiber’s diagram for κ-FLC showed the highest sensitivity (91.8%) but lower specificity (45.8%).
Interpretation:
The κ-FLC index is a valuable quantitative biomarker of intrathecal immunoglobulin synthesis in MS, with higher thresholds improving diagnostic specificity, which could enhance clinical decision-making.
Limitations:
The study is based on a single-center population, which may limit generalizability and the applicability of findings to broader populations. Further validation of higher κ-FLC index thresholds in independent series is needed.
Conclusion:
Higher κ-FLC index thresholds may improve diagnostic specificity in real-world clinical settings and should be validated in independent series to confirm their utility.
