Neuromyelitis Optica Spectrum Disorders Differ By Autoantibody Type, but Not Clinical Course, between Racial Groups

Background: Neuromyelitis Optica Spectrum Disorder (NMOSD) is a rare, frequently disabling constellation of inflammatory CNS syndromes which may be grouped by pathogenic autoantibodies to aquaporin-4 (AQP4-IgG), myelin oligodendrocyte glycoprotein (MOG-IgG), or seronegativity to both antibodies. Previous analysis of NMOSD in the University of Alabama at Birmingham (UAB) neurology clinics found overrepresentation of NMOSD among Black patients, driven mainly by AQP4-IgG seropositivity, consistent with other published cohorts. However, reports on racial differences in NMOSD-related disability have been inconsistent, possibly due to small cohort sizes and regional differences in patient populations.

Objectives: To examine differences in disability accrual among patients with NMOSD by racial group in a large academic neurology clinic in the southern United States.

Methods: The i2b2 search engine was used to search all electronic health records at UAB for NMOSD diagnostic codes. A retrospective chart review was conducted to abstract demographics, antibody status, and clinical disease course for all available records. Chi-square or Fisher’s Exact tests were used for comparisons, with p<0.05 considered meaningful. Analysis was completed using SPSS.

Results: Among 121 total patients with NMOSD, 73 (60.3%) identified as Black, 31 (25.6%) as White, 8 as Asian (6.6%), and 9 as other (7.5%). AQP4-IgG positive status comprised the majority of patients among Blacks (79.5%) and Asians (87.5%), but only a plurality among Whites (41.9%, p=0.01), who were more likely than other groups to be categorized as MOG-IgG positive (35.5%) or seronegative (22.6%).

Considering all NMOSD subtypes together, no significant differences between racial groups were seen for presenting symptoms of transverse myelitis, optic neuritis, or area postrema syndrome, or in likelihood of acquiring fixed disability from visual or ambulatory impairment. However, when limiting dataset to AQP4-IgG seropositive Blacks and Whites, residual change in visual acuity was somewhat more common among Whites (46.2%) than Blacks (34.5%), although the result was non-significant. Isolated ambulatory disability affected 29.6% of patients, while combined visual and ambulatory disability affected 8.5%; proportions did not differ by racial group.

Conclusions: Although prevalence of NMOSD-associated antibodies differ by race, clinical presentation and disability outcomes do not vary by race in this large, single center cohort.