Quantitative Contribution of Clinical Attacks to Residual Disability in Patients With AQP4-Antibody Neuromyelitis Optica Spectrum Disorder

BACKGROUND AND OBJECTIVES: Disease-related disability in aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) is solely attributed to clinical attacks. However, few studies have assessed the relationship between attacks and residual disability in NMOSD. Thus, we aimed to quantify the contribution of clinical attacks to the residual disability in patients with AQP4-NMOSD. METHODS: This retrospective observational single-center study enrolled patients from the Oxford National NMO Service, with the inclusion criteria as (1) AQP4-NMOSD diagnosis and (2) availability of at least 1 disability score (Expanded Disability Status Scale [EDSS] or logarithm of the minimum angle of resolution [LogMAR] score) recorded ≥6 months after attack (defined as residual disability). The outcome measures were EDSS and LogMAR scores. Univariable and multivariable linear mixed-effect models were used to quantify the effect of clinical relapses on the outcomes. RESULTS: < 0.001) in the LogMAR score. Race, sex, and timing of acute treatment did not significantly affect these disability outcomes (EDSS and LogMAR scores). DISCUSSION: The quantitative contribution of relapse to the residual disability in patients with AQP4-NMOSD varies across phenotypes, and this relapse-related disability progression may also vary by the onset age. Although this retrospective single-center study may need validation in other data sets, these findings may help predict disability and provide a modeling tool for longer term disability in the cost-effective analysis of newer interventions.