Factors Associated With Disability Improvement and Worsening Independent of Attacks in Patients With AQP4-IgG+ NMOSD...

Disability trajectories in aquaporin-4 immunoglobulin G-seropositive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are primarily driven by attack-related damage. Confirmed disability worsening (CDW) independent of attacks has been described but occurs infrequently in AQP4-IgG+ NMOSD and MOGAD. Confirmed disability improvement (CDI) has not been evaluated in large cohorts. We determined the frequency of CDI and CDW independent of attacks and identified clinical factors associated with these outcomes in AQP4-IgG+ NMOSD and MOGAD.

This retrospective, multicenter cohort study analyzed data from the German Neuromyelitis Optica Study Group (NEMOS) registry. Adult patients with AQP4-IgG+ NMOSD or MOGAD and longitudinal Expanded Disability Status Scale (EDSS) assessments were included. EDSS episodes were defined as periods with ≥3 EDSS assessments without attacks, obtained ≥90 days after attack. CDW and CDI were defined as sustained EDSS increase or decrease (≥1.5 for baseline EDSS 0; ≥1.0 for EDSS 1.0-5.5; ≥0.5 for EDSS ≥6.0) confirmed after at least 6 months. The primary outcomes were annualized CDI and CDW rates. Risk factors were assessed using multivariable Anderson-Gill regression models.

A total of 338 EDSS episodes of 307 patients (n: 202/105, median age at EDSS change: 56/41 years, 88/49% female, both p < 0.001; AQP4-IgG+ NMOSD/MOGAD) were included. Adjusted annualized CDI and CDW rates did not differ between AQP4-IgG+ NMOSD (CDI: 0.083, 95% CI 0.029-0.233; CDW: 0.025, 95% CI 0.007-0.092) and MOGAD (CDI: 0.057, 95% CI 0.012-0.277; CDW: 0.036, 95% CI 0.002-0.513). In AQP4-IgG+ NMOSD, a lower number of prior attacks was associated with higher CDI rates (hazard ratio [HR] 0.89, 95% CI 0.82-0.97). Younger age was associated with increased CDI rates in both AQP4-IgG+ NMOSD and MOGAD (HR 0.96, 95% CI 0.94-0.99, for both).

CDI and CDW independent of attacks, although rare, occur in AQP4-IgG+ NMOSD and MOGAD. The association between fewer prior attacks and higher CDI rates in AQP4-IgG+ NMOSD underscores the importance of early attack prevention. Limitations include the retrospective design, and the limited number of CDI and CDW events.