Relapse-related outcomes in the Danish population-based AQP4- antibody seropositive neuromyelitis optica spectrum disorder cohort

Background: The disease course of AQP4-antibody seropositive neuromyelitis optica spectrum disorder (AQP4-Ab + NMOSD) is unpredictable and variable. We aimed to examine relapse-related outcomes. Methods: In a nationwide historically prospective AQP4-Ab + NMOSD cohort, relapse outcomes, relapse and maintenance treatments were analyzed by mixed-effects linear and logistic regression models. Results: Among sixty-six patients (median follow-up: 99.5 months) there were 350 relapses and 272 relapse treatments. Delayed immunosuppression after the first relapse and brainstem (BS) relapses were associated with higher Expanded Disability Status Scale (EDSS) scores at final follow-up. Optic neuritis (ON) was associated with higher relapse frequency. Higher age and male sex were associated with more severe transverse myelitis (TM) (p < 0.032), and male sex was also associated with worse ON recovery (p = 0.036). ON was more likely after TM (OR: 3.2, 95% CI: 1.7-6.0; p < 0.001) and vice versa (OR: 2.9, 95% CI: 1.6–5.2; p < 0.001). BS relapse was also more likely after TM (OR: 2.8, 95% CI: 1.2–6.4; p = 0.016) and vice versa (OR: 2.4; 95% CI: 1.1–5.3; p = 0.031). Rituximab treatment correlated with lower EDSS score at final follow-up (p = 0.044). Conclusion: Earlier initiation of immunosuppressive maintenance treatment limited the accumulation of disability in NMOSD. Recognizing relapse patterns could aid in tailoring monitoring and treatment choices.