Demographic and Clinical Characteristics of Aquaporin-4 Antibody-Positive Neuromyelitis Optica Spectrum Disorder in Canadian Adults

OBJECTIVE: Neuromyelitis optica spectrum disorder (NMOSD) is a rare and disabling neuroinflammatory disorder. Previous studies of aquaporin-4 IgG-positive (AQP4+) NMOSD in Canada have been limited by small sample sizes and regional focus. This study aimed to characterize the sociodemographic and clinical profile of individuals living with AQP4+ NMOSD and the treatment landscape in a multicenter study. METHODS: Data were collected from the CAnadian Neuromyelitis OPTIca Spectrum Disorder and other atypical demyelinating diseases Cohort Study (CANOPTICS), a prospective longitudinal study involving seven Canadian centers. Participants were diagnosed with AQP4+ NMOSD using the 2015 International Panel for NMO Diagnostic criteria. We analyzed sociodemographic and clinical characteristics in addition to treatment utilization over time. RESULTS: 133 participants with AQP4+ NMOSD were included, with a mean (SD) age of 52.0 (15.0) years at enrollment and 45.9 (15.5) years at index attack. Most were female (84.9%), ethnically and racially varied (33.3% North American or European White, 25.2% African/Caribbean Black, 22.7% East/Southeast Asian) and born abroad (63.3%). Two-thirds had moderate or mild disability, as measured by an Expanded Disability Status Scale of 3.5 or less. Azathioprine was the most used first-line therapy (59.3%), followed by mycophenolate mofetil (12.5%) and rituximab (10.5%). Use of novel monoclonal antibodies (MAbs) was least common (6.3%); however, first-line use of rituximab and novel MAbs increased in recent years (2018-2023). CONCLUSIONS: Canadians with AQP4+ NMOSD are predominantly female and ethnically and racially varied, with more favorable outcomes than in previous reports. Despite a trend toward increasing use of rituximab and novel MAbs, these higher-efficacy treatments remain underutilized for NMOSD in Canada.