Clinical characteristics of very late-onset neuromyelitis optica spectrum disorder

Background: The typical age at onset of neuromyelitis optica spectrum disorder (NMOSD) is between 30 and 40 years. A growing awareness about the disease and advances in diagnostic techniques have led to an increase in the number of patients being diagnosed with very late-onset (VLO) NMOSD. This study compared the clinical characteristics, treatments, and prognoses between patients with VLO-NMOSD or late-onset (LO) NMOSD. Methods: Patients in our study were assigned to two groups based on age at onset of the disease: LO-NMOSD (5070 years old at onset) and VLO-NMOSD (> 70 years old at onset). We compared clinical characteristics, magnetic resonance imaging of lesions, prognosis, and treatments between the two groups. Results: We collected data from 12 VLO-NMOSD patients with a median age at onset of 74.0 years (interquartile range, 72.6-75.9 years) and 104 LO-NMOSD patients with a median age at onset of 56.0 years (55.8-57.9 years). There were a high proportion of female patients in both the VLO-NMOSD group (9, 75.0%) and the LO-NMOSD group (91, 87.5%). Our study indicated that VLO-NMOSD patients had significantly higher expanded disability status scale (EDSS) scores (8.5 vs 4.0, p = 0.01), higher motor disability rates (41.7% vs 9.6%, p = 0.002), and higher mortality rates (25.0 vs 4.8%, p = 0.044) at last follow-up. However, patients with VLO-NMOSD had lower rates of immunosuppressant usage (50.0% vs 76.9%, p = 0.044). Age at onset was positively correlated with EDSS score at remission (r = 0.49, p < 0.001). Conclusion: VLO-NMOSD was associated with higher EDSS score at remission, higher rates of mortality and motor disability, but lower rates of immunosuppressive treatment usage than LO-NMOSD. Future studies are needed to understand the effects of NMOSD on older patients, and to seek suitable treatment to improve their prognosis.