bands; cerebrospinal-fluid analysis; criteria; csf; diagnosis; disease course; immunoglobulin-m; intrathecal IgM synthesis; multiple sclerosis; oligoclonal igm; onset; predicts; prognostic factor

Background: Intrathecal IgM synthesis has been identified as an adverse prognostic factor in patients with multiple sclerosis (MS); however, some studies have not confirmed this association. The objective of this study was to evaluate the clinical utility of intrathecal IgM synthesis for prediction of disease activity and disability in patients after the first demyelinating event of MS. Methods: We conducted a single-centre prospective observational cohort study at the Department of Neurology, University Hospital Ostrava, Czech Republic. Intrathecal IgM synthesis was demonstrated by the presence of cerebrospinal fluid-restricted oligoclonal IgM bands and calculated using the Reiber, Auer, and Ohman formula and IgM index. Results: A total of 61 patients with a clinically isolated syndrome or early relapsing-remitting MS were enrolled into the analysis of which 37 (61 %) were women. The median age at the disease onset was 32 years (inter-quartile range [IQR] 25 - 42), and the median disease duration was 2.8 years (IQR 2.4 - 3.5). Thirty-eight (62 %) patients experienced a second relapse of MS with a median of 312 days (IQR 192 - 424), and 29 (47.5 %) developed magnetic resonance imaging (MRI) activity during the follow-up. Intrathecal IgM synthesis did not affect the risk of a second relapse or evidence of MRI activity in univariate and multivariate Cox regression analysis. There was no significant difference in disability using the Expanded Disability Status Scale and progression index in patients with or without intrathecal IgM synthesis. Conclusion: This prospective cohort study did not demonstrate that intrathecal IgM synthesis is a risk factor for a second relapse or MRI activity. It was not associated with higher disability in patients after the first demyelinating event.