Low prevalence of inflammatory bowel disease among patients with seropositive neuromyelitis optica spectrum disorder in two large referral centers.

Patients with Neuromyelitis Optica Spectrum Disorders (NMOSD) have a well-recognized predilection to autoimmune comorbidities, of which systemic lupus erythematosus (SLE), Sjögren's syndrome (SjS), and autoimmune thyroid diseases are the most common. The question of whether some autoimmune diseases, such as inflammatory bowel disease (IBD), may not be overrepresented (or may even be underrepresented) in NMOSD has not received much attention. Here, we retrospectively reviewed the electronic medical records of all patients diagnosed with NMOSD in our two large referral centers (NYU and MGB), as well as patients with two neuroinflammatory disorders as comparator groups (myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and MS), and calculated the rates of IBD, SLE, SjS, autoimmune thyroid disorders, and myasthenia gravis (MG) in these groups. We found that 1 out of 347 NMOSD patients had a diagnosis of IBD (0.3%), and this patient was seronegative for anti-AQP4 autoantibodies, while 4/271 patients in the MS group (1.5%), 2 of whom were exposed to anti-CD20 therapy, had IBD, and 2/366 MOGAD patients (0.8%), neither of whom was exposed to anti-CD20 therapy, had IBD. In contrast, the rate of the other four autoimmune conditions was significantly higher in NMOSD (24%) than in MOGAD (8.5%, p < 0.0001) or MS (5.2%, p < 0.0001). Thus, IBD was not diagnosed in any of our 317 seropositive NMOSD patients, despite the fact that this group had a higher use of B-cell depletion than patients with MS and MOGAD. We discuss the various hypotheses that may explain this observation.