Neuromyelitis optica (NMO) is often associated with systemic autoimmune diseases or serological markers of non-organ-specific autoimmunity, and has been most frequently associated with Sjögren's syndrome and anti-Ro/SSA antibody (SSA-Ab) positivity in Asian populations.
We evaluated the clinical significance of anti-Ro/SSA antibody positivity in patients with NMO spectrum disorder (NMOSD).
We retrospectively collected data from 106 consecutive patients with NMOSD and reviewed clinical features and laboratory findings. All patients underwent tests for SSA-Ab and anti-aquaporin-4 antibody (AQP4-Ab) using cell-based indirect immunofluorescence assays.
Among 106 patients, 20 (18.9%) were positive for SSA-Ab. Of 48 AQP4-Ab-positive patients, 18 (37.5%) had SSA-Ab. AQP4-Ab seropositivity was 90.0% in patients positive for SSA-Ab, and 32.6% in patients without SSA-Ab (p<0.001). Presence of SSA-Ab was associated with systemic autoimmune diseases, including Sjögren's syndrome (p<0.001) and systemic lupus erythematosus (p=0.003), and with the presence of non-organ-specific autoantibodies such as anti-nuclear antibody and anti-dsDNA antibody in patients with NMOSD, but was not associated with annualized relapse rate or final Expanded Disability Status Scale score independent of AQP4-Ab positivity.
We found that the presence of SSA-Ab was highly associated with seropositivity for AQP4-Ab in patients with NMOSD.