Time to Disability Milestones and Annualized Relapse Rates in NMOSD and MOGAD

Objective To investigate accumulation of disability in neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein‐antibody‐associated disease (MOGAD) in a changing treatment landscape. We aimed to identify risk factors for the development of disability milestones in relation to disease duration, number of attacks, and age. Methods We analyzed data from individuals with NMOSD and MOGAD from the German Neuromyelitis Optica Study Group registry. Applying survival analyses, we estimated risk factors and computed time to disability milestones as defined by the Expanded Disability Status Score (EDSS). Results We included 483 patients: 298 AQP4‐IgG + NMOSD, 52 AQP4‐IgG − /MOG‐IgG − NMOSD patients, and 133 patients with MOGAD. Despite comparable annualized attack rates, disability milestones occurred earlier and after less attacks in NMOSD patients than MOGAD patients (median time to EDSS 3: AQP4‐IgG+ NMOSD 7.7 (95% CI 6.6–9.6) years, AQP4‐IgG − /MOG‐IgG − NMOSD 8.7 ) years, MOGAD 14.1 (95% CI 10.4–27.6) years; EDSS 4: 11.9 (95% CI 9.7–14.7), 11.6 (95% lower CI 7.6) and 20.4 (95% lower CI 14.1) years; EDSS 6: 20.1 (95% CI 16.5–32.1), 20.7 (95% lower CI 11.6), and 37.3 (95% lower CI 29.4) years; and EDSS 7: 34.2 (95% lower CI 31.1) for AQP4‐IgG + NMOSD). Higher age at onset increased the risk for all disability milestones, while risk of disability decreased over time. Interpretation AQP4‐IgG + NMOSD, AQP4‐IgG − /MOG‐IgG − NMOSD, and MOGAD patients show distinctive relapse‐associated disability progression, with MOGAD having a less severe disease course. Investigator‐initiated research has led to increasing awareness and improved treatment strategies appearing to ameliorate disease outcomes for NMOSD and MOGAD. ANN NEUROL 2024;95:720–732