Patients with neuromyelitis optica spectrum disorder (NMOSD) are commonly misdiagnosed, leading to delays in treatment initiation, according to an international study published in Neurology and Therapy.

The study, which analyzed clinical records from the United States, Germany, Italy, Brazil, South Korea, and China, found that roughly 25% of aquaporin-4 (AQP4) immunoglobulin G (IgG)-seropositive adults with NMOSD were initially misdiagnosed. Multiple sclerosis was the most common misdiagnosis (44%), followed by idiopathic myelitis (10%), optic neuritis (8%), and stroke/transient ischemic attack (7%).

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Patients who were initially misdiagnosed had a much longer delay from first symptoms to treatment initiation than those who were correctly diagnosed (21.2 vs 9.9 months; P <.05). These misdiagnosed patients also experienced more relapses (3.3 vs 2.8; P <.05) and had a higher proportion of severe attacks (23% vs 10%).

Slightly more than half of newly diagnosed patients with NMOSD (53%) initiated maintenance therapy within 2 months of diagnosis. The main reasons for not initiating maintenance therapy were “stable disease” (40%), patient refusal (32%), and cost or access restrictions (19%). The initial attack severity appeared to play a role in the timing of treatment initiation as well, with 13% of patients experiencing a severe attack receiving immediate treatment compared to only 5% of patients with severe attacks who had a delay in treatment initiation.

The most common first-line therapy was oral corticosteroids/immunosuppressive therapies (ISTs), with monoclonal antibody treatments also being used at lower percentages in most countries. Only the United States had a roughly equal distribution of treatment with oral corticosteroids/ISTs and monoclonal antibodies.

Lack of efficacy (54%) was the most common reason given for treatment changes. Other top reasons included lack of tolerability (19%), patient request (16%), and adverse events (15%). The severity of relapse seemed to be a factor for a change in therapy, with 19% of patients who were changed to monoclonal antibody treatment having a severe relapse. Only 8% of patients who changed to a different oral corticosteroid/IST had a severe relapse.

“Relapse severity was a factor that guided the neurologist’s decisions on treatment initiation/switch, and future studies using real-world evidence to assess relapse severity in treatment initiation/switch are required to improve understanding of this disease and revise NMOSD treatment recommendations,” the authors wrote.

During the study, 1185 NMOSD patient records were reviewed and analyzed. Following the review, 34 patients were interviewed, with 33 patients’ data being included in the study.


Min JH, Capobianco M, Welsh C, et al. Understanding treatment decisions in neuromyelitis optica spectrum disorder: a global clinical record review with patient interviews. Neurol Ther. Published online February 24, 2023. doi:10.1007/s40120-022-00431-y