Relapse and disability outcomes in incident MOGAD patients undergoing watchful waiting after onset

Background: Observation off chronic steroids-sparing immunotherapy (watchful waiting) is often recommended after the onset attack of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) given the variable relapse risk, but the outcomes of this approach are unexplored. Objectives: To determine the risk of relapse and unfavorable disability outcomes in MOGAD patients who underwent watchful waiting approach after the onset attack. Methods: In this international, multicenter, retrospective case series in four tertiary-care centers in Canada, Israel, Thailand, and the United States, patients who fulfilled the 2023 MOGAD diagnostic criteria, presented to the participating institutions with the first clinical attack (incident cases), and had at least 3 years of follow-up were identified (n = 81). Only incident cases were included to avoid referral bias. Results: The median age was 31 (IQR 18–47) years, 57 % were female, and the median follow-up was 6.3 (IQR 4.5–10.1) years. After onset, 65 (80 %) underwent watchful waiting. Forty-one (63 %) had relapses with annualized relapse rate of 0.27 (IQR 0.15–0.44). Unfavorable disability outcomes (Expanded Disability Status Scale score ≥2.0) were observed in 12/64 (19 %) watchful-waiting patients (7 from the onset attack; 4 from relapses; 1 unclear). Conclusions: Given that one-third of watchful waiting patients remained monophasic and unfavorable disability outcomes from relapses were uncommon, a continued observation off chronic steroids-sparing immunotherapy could be an option for a subset of MOGAD patients.