Longitudinal follow-up of serum biomarkers in patients with neuromyelitis optica spectrum disorder

Background: Recently, several serum biomarkers have been proposed in Neuromyelitis Optica Spectrum Disorders (NMOSD) to monitor disease activity. Objective: The objective of the study is to evaluate the longitudinal clinical value of serum biomarkers in patients with NMOSD. Methods: We prospectively recruited consecutive NMOSD patients with anti-aquaporin-4 antibody and obtained serum samples at enrollment, after 6–12 months of follow-up (main period), and at attacks. Using single-molecule array assays, we evaluated longitudinal changes of serum neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and GFAP/NfL levels. Results: Overall, 64 patients (58 women) were enrolled (age: 51 years, disease duration: 6.7 years) and 133 samples were obtained. Among patients who did not develop new attacks during the main period (n = 62), serum levels of NfL, GFAP, and GFAP/NfL were significantly decreased over time in patients with attacks (