Time to Treat First Acute Attack of Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

Importance A proportion of people with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) have a relapsing disease course and persistent anti–myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) seropositivity. Few studies have investigated whether treatment of the first MOGAD attack is associated with the long-term disease course and/or MOG-IgG seronegative conversion. Objective To investigate the association of time to treat the first acute MOGAD attack with relapse risk and MOG-IgG serostatus. Design, Setting, and Participants This was a retrospective, nationwide, multicenter cohort study involving 14 secondary or tertiary hospitals in South Korea between November 2009 and August 2023. People with adult-onset MOGAD, who either had a relapse or were followed up for more than 12 months after disease onset and had a detailed medical record of their first attack, were included. Individuals were excluded for adolescent-onset MOGAD or short disease duration. Exposures Patients were categorized based on the time to treat the first acute MOGAD attack: early (<5 days), intermediate (5-14 days), and late (not treated within 14 days). Main Outcomes and Measures A multivariable analysis for clinical and treatment factors associated with relapsing disease course and/or MOG-IgG seronegative conversion. Further subgroup analyses were conducted among those without long-term nonsteroidal immunosuppressant (NSIS) maintenance treatment. Results Among the 315 individuals screened, 75 were excluded. A total of 240 patients (median [IQR] age at onset, 40.4 [28.8-56.1] years; 125 female [52.1%]) with median (IQR) disease duration of 3.07 (1.95-6.15) years were included. A total of 110 of 240 patients (45.8%) relapsed after a median (IQR) of 0.45 (0.18-1.68) years, and 29 of 116 patients (25.0%) experienced a conversion to seronegative MOG-IgG. Both the time to treatment of the first MOGAD attack (late vs early: adjusted hazard ratio [aHR], 2.64; 95% CI, 1.43-4.84; P = .002; intermediate vs early: aHR, 2.02; 95% CI, 1.10-3.74; P = .02) and NSIS maintenance treatment (aHR, 0.24; 95% CI, 0.14-0.42; P < .001) were independently associated with the risk of relapse. In a subgroup without NSIS maintenance, the time to treat of the first MOGAD attack was still associated with higher risk of relapse (late vs early: aHR, 3.51; 95% CI, 1.64-7.50; P = .001; intermediate vs early: aHR, 2.68; 95% CI, 1.23-5.85; P = .01). Lastly, the time to treat of the first MOGAD attack was also associated with MOG-IgG seronegative conversion (early vs late: adjusted odds ratio, 7.04; 95% CI, 1.58-31.41; P = .01), whereas NSIS maintenance treatment was not. Conclusions and Relevance Results of this cohort study suggest that early treatment of the first acute MOGAD attack was associated with a reduction in the proportion of relapsing disease course and an increase in the likelihood of MOG-IgG seronegative conversion. These data suggest that timing of acute phase treatment for the first MOGAD attack can be associated with the long-term prognosis and autoimmune status of patients.