Racial and Ethnic Disparities in the Incidence of Neuromyelitis Optica Spectrum Disorder
Angus Lee1, Jessica Smith2, Bonnie Li2, Radostina Iordanova1, Annette Langer-Gould1
1Kaiser Permanente Los Angeles Medical Center, 2Research & Evaluation, Southern California Permanente Medical Group
Objective:
To determine the incidence of Neuromyelitis Optica Spectrum Disorder (NMOSD) in a large, contemporary, multi-ethnic cohort.
Background:
Ecological comparisons have suggested that the NMOSD incidence may be higher in African and Asian countries, but no studies have examined racial/ethnic differences within the same population.
Design/Methods:
We conducted a retrospective cohort study among the multi-ethnic members of Kaiser Permanente Southern California, 2010-2021. The complete electronic health records of individuals with ≥1 NMOSD ICD code were reviewed to identify patients who met the 2015 NMOSD diagnostic criteria. Crude and age and sex-standardized incidences stratified by race and ethnicity were estimated according to the 2020 US Census population.
Results:
We identified 127 newly diagnosed NMOSD patients of whom 89.0% were aquaporin-4 antibody positive. The median age at diagnosis was 46.6 years (IQR 32.7-57.6, range 6.0-84.9) and 110 (86.6%) were females. The female preponderance was more pronounced in Asian (95.2%), Hispanic (90.5%) and Black persons (89.7%) than White individuals (68.0%) The age- and sex-standardized incidence of NMOSD per 1 million person-years was significantly higher in Black persons (9.21, 95%CI 6.27–12.15) compared to all other racial/ethnic groups. The incidence in Asian persons (3.77, 95%CI 2.15–5.40) was higher than Hispanic (2.02, 95%CI 1.41–2.63) or White, non-Hispanic persons (1.56, 95%CI 0.95–2.18) whose rates were similar. Black persons had a higher NMOSD incidence across all age strata compared to other groups except 65 and older where the incidence was similar across all racial and ethnic groups.
Conclusions:
In this large, contemporary cohort, we found that NMOSD is a female-predominant disease that disproportionately affects Black and, to a lesser extent, Asian persons. Although NMOSD incidence is much lower, its pattern is more like systemic lupus erythematosus than multiple sclerosis.