BACKGROUND: Aquaporin-4 neuromyelitis optica spectrum disorder (AQP4-NMOSD) often coexists with other autoimmune diseases (AIDs), whereas such comorbidities are less common in myelin oligodendrocyte glycoprotein antibody disease (MOGAD). This study investigates the impact of additional AIDs on early relapse recovery and disability in patients with AQP4-NMOSD and MOGAD. METHODS: This retrospective study included patients aged > 16 years with AQP4-NMOSD (n = 175) or MOGAD (n = 221), who were followed at a nationally commissioned Oxford service and categorized based on the presence of at least one AID. Outcomes included recovery from the onset attack, visual recovery after the first optic neuritis (ON) attack (≥ 6 months post attack), time to first relapse and time to death. Incomplete visual recovery was defined as visual acuity worse than LogMAR 0.1. Optical coherence tomography (OCT) assessed retinal nerve fiber layer thickness and ganglion cell-inner plexiform layer volume in a subset. RESULTS: In the AQP4-NMOSD cohort, 28% (n = 49) had at least one AID, compared to 11.3% (n = 25) in the MOGAD cohort (p