Relapse and Neurological Prognosis in Myelin Oligodendrocyte Glycoprotein Antibody‐Associated Disease: A Retrospective Secondary Analysis of a Japanese Nationwide Epidemiologic Survey

ABSTRACT Background Some patients with myelin oligodendrocyte glycoprotein antibody‐associated disease (MOGAD) experience multiple relapses and poor prognoses; however, the factors associated with these outcomes are unclear. This study aimed to identify factors associated with relapse and neurological prognosis in patients with MOGAD. Methods We retrospectively analyzed clinical data from a nationwide epidemiological survey of MOGAD conducted in Japan in 2021 to examine the associations of clinical characteristics with relapse and neurological prognosis. Prognosis was assessed using the Expanded Disability Status Scale (EDSS), comparing patients with EDSS scores ≤ 2 (good prognosis) to those with EDSS scores ≥ 4.5 (poor prognosis). In the multivariate analyses, clinical characteristics, phenotypes, cerebrospinal fluid data, acute‐phase treatments at disease onset, and maintenance treatments were analyzed. Outcomes were also compared between patients with oligoclonal IgG bands (OCB) positivity and negativity. Results Of the 679 patients with relapse information, 371 (54.6%) experienced relapse, whereas 308 (45.4%) did not. In the multivariate analysis, OCB positivity was associated with relapse, whereas plasma exchange (PE) administration at disease onset was associated with a monophasic course. Of the 637 patients with EDSS scores, 541 (84.9%) had a good prognosis, whereas 46 (7.2%) had a poor prognosis. In the multivariate analysis, PE administration at disease onset was associated with poor prognosis. The number of patients experiencing relapse was higher among those with OCB positivity, although no differences were observed in the median interval from onset to the first relapse. Conclusion In MOGAD, OCB positivity may predict relapse, and adequate acute‐phase treatment may reduce relapse risk.