Race May Affect Phenotype, Age of Onset, and Severity of Neuromyelitis Optica Spectrum Disorder
The study's findings indicate that race may affect the disease course of NMOSD.
Asian and black American/European patients seropositive for anti-aquaporin-4 antibody neuromyelitis optica spectrum disorder (NMOSD) are more likely to be younger at time of disease onset and have brainstem involvement during their disease course, according to retrospective review results published in Neurology.
Patients with anti-aquaporin-4 antibody-seropositive NMOSD who were followed at centers in Denmark, Germany, South Korea, the United Kingdom, the United States, and Thailand were included in the review. The demographics of the cohort included Asian (n=304), white (n=207), and black American/European (n=92) patients. At last follow-up, the median disease duration in the entire cohort was 8 (range, 0.3-38.4) years.
The primary event of interest was the occurrence of severe irreversible motor disability (Expanded Disability Status Scale score, ≥6.0) or visual disability (converted visual function scale score, ≥3). Age, sex, ethnicity, syndrome type (at onset, second attack, and third attack), number of attacks before and after immunosuppressive treatment, first attack severity, presence of longitudinally extensive transverse myelitis on magnetic resonance imaging at onset, brain magnetic resonance imaging abnormalities, presence of symptomatic brain attack, time and duration of treatment, treatment type, concurrent systemic or localized autoimmune disease, and cerebrospinal fluid-specific oligoclonal bands were assessed.
Compared with white patients, Asian and black American/European patients were significantly younger at time of disease onset (mean, 44 vs 36 and 33 years, respectively; P <.001). In addition, a significantly lower proportion of white patients had brainstem involvement during their disease course compared with Asian and black American/European patients (23% vs 42% and 38%, respectively; P <.001). Black American/European patients vs Asian and white patients were more likely to experience severe attacks, as defined by either a visual acuity of ≤0.1 in ≥1 eye or an EDSS score of ≥6.0 at nadir (58% vs 46% and 38%, respectively; P =.005).
Independent predictors of severe motor disabilities at last follow-up included older age at onset (odds ratio [OR] 1.05; 95% CI, 1.034-1.067) and having a higher number of attacks before (OR 1.133; 95% CI, 1.075-1.193) and after (OR 1.185; 95% CI, 1.076-1.306) immunosuppressive treatment, according to the multivariable analysis. Factors associated with severe residual visual disability included disease duration (OR 1.05; 95% CI, 1.011-1.09), higher number of attacks before therapy (OR 1.125; 95% CI, 1.059-1.194), and optic neuritis presentation at onset (OR 5.61; 95% CI, 3.746-8.394).
Limitations of this study included its lack of a population-based design and the reliance on self-reporting for identifying racial background.
Findings from this review may help improve understanding of racial differences in NMOSD that "may yield important insight into NMOSD pathogenesis, improve early diagnosis, and help in identifying the best treatment strategy, tailored to the needs of individual target populations."
Kim S-H, Mealy MA, Levy M, et al. Racial differences in neuromyelitis optica spectrum disorder. Neurology. 2018;91(22):e2089-e2099.