Relapse or no relapse in multiple sclerosis: Can disease activity biomarkers support the clinician?

Background: In relapsing-remitting multiple sclerosis (RRMS), the assessment of clinical disease activity can be challenging.

Objectives: To determine the diagnostic potential of serum neurofilament light (sNfL) and glial fibrillary acidic protein (sGFAP) to distinguish a relapse from other causes of deterioration.

Methods: In this multicenter, prospective study, RRMS patients with new neurological symptoms in the last 14 days were followed for 12 weeks. A diagnosis was established by the treating physician or, when in doubt, a panel of experienced neurologists. Blood samples were taken at baseline and week 12.

Results: A total of 65 patients were included. At baseline, patients with a clear relapse had a significantly higher median sNfL (14.6 pg/mL) than those with a clear other cause (9.5 pg/mL, p = 0.004). Although not significant after correction for multiple testing, median sGFAP was also higher in relapse patients (73.0 vs 64.6 pg/mL, p = 0.036). An sNfL value below 6.0 pg/mL had a high sensitivity (67% at baseline (CI 22.3-95.7%) and 100% at follow-up (CI 54.1-100%)) to rule out a relapse.

Conclusions: Analysis of sNfL level can be useful as an add-on investigation to determine whether disease activity is present in patients with RRMS presenting with new symptoms.