To investigate whether -free light chain (-FLC) index predicts multiple sclerosis (MS) disease activity independent of demographics, clinical characteristics, and MRI findings.
Patients with early MS who had CSF and serum sampling at disease onset were followed for 4 years. At baseline, age, sex, type of symptoms, corticosteroid treatment, and number of T2 hyperintense (T2L) and contrast-enhancing T1 lesions (CELs) on MRI were determined. During follow-up, the occurrence of a second clinical attack and start of disease-modifying therapy (DMT) were registered. -FLCs were measured by nephelometry, and -FLC index calculated as [CSF -FLC/serum -FLC]/albumin quotient.
A total of 88 patients at a mean age of 33 ± 10 years and female predominance of 68% were included; 38 (43%) patients experienced a second clinical attack during follow-up. In multivariate Cox regression analysis adjusting for age, sex, T2L, CEL, disease and follow-up duration, administration of corticosteroids at baseline and DMT during follow-up revealed that -FLC index predicts time to second clinical attack. Patients with -FLC index >100 (median value 147) at baseline had a twice as high probability for a second clinical attack within 12 months than patients with low -FLC index (median 28); within 24 months, the chance in patients with high -FLC index was 4 times as high as in patients with low -FLC index. The median time to second attack was 11 months in patients with high -FLC index whereas 36 months in those with low -FLC index.
High -FLC index predicts early MS disease activity.
Classification of Evidence
This study provides Class II evidence that in patients with early MS, high -FLC index is an independent risk factor for early second clinical attack.