Clinical and immunological differences between primary and autoimmune-associated neuromyelitis optica spectrum disorders: a retrospective study.

Introduction: Neuromyelitis optica spectrum disorder (NMOSD) is a rare immune-mediated disease affecting the spinal cord and optic nerves. While NMOSD has been widely studied, limited data exist on the subset associated with autoimmune diseases (AD-NMOSD), particularly in Taiwanese patients. Additionally, relapse and prognostic factors in AD-NMOSD remain unclear.

Methods: We retrospectively analysed 71 NMOSD cases diagnosed between 2008 and 2023 at Taipei Veterans General Hospital. Clinical features, laboratory findings, autoimmune comorbidities, imaging and treatments were examined. Patients were stratified by relapse status and the presence of severe sequelae.

Results: Among 71 NMOSD cases, 26 (37%) patients had AD-NMOSD. While no significant differences were observed in the number or severity of relapses and sequelae between AD-NMOSD and primary (p)-NMOSD, patients with AD-NMOSD exhibited lower white blood cell counts, haemoglobin, platelet counts, immunoglobulin G and C reactive protein levels. Specific risk factors for relapse in AD-NMOSD included onset age under 50 years, concurrent SLE and a longer duration of SLE before NMOSD presentation. In both AD-NMOSD and p-NMOSD, more relapses were associated with severe neurological sequelae. Although relapse-free survival did not differ significantly between the two groups, patients with AD-NMOSD tended to have a longer period without severe sequelae.

Discussion: Taiwanese patients with AD-NMOSD show distinct laboratory characteristics compared with those without autoimmune diseases. Younger age and longer disease duration are key risk factors for relapses, which are linked to more severe neurological sequelae. Despite various treatments, no significant differences were found in relapse rates or sequelae severity, highlighting the need for personalised management strategies.