Age at onset predicts outcome in aquaporin-4-IgG positive neuromyelitis optica spectrum disorder from a United Kingdom population

Abstract

Background: There are few studies exploring the prognostic factors in patients with aquaporin-4 (AQP4)-IgG positive neuromyelitis optica spectrum disorder (NMOSD).

Objective: To assess the predictors of outcome in patients with AQP4-antibody positive NMOSD from a United Kingdom (UK) population.

Methods: A retrospective study of 52 patients from 2 neuroscience centres in the UK Midlands.

Results: The most common initial presentations were acute myelitis and optic neuritis, with 22/52 cases (42.3%) each. Relapsing course was seen in 32 patients (61.5%) with mean annualised relapse rate of 0.43 (standard deviation 0.45) and a mean interval time to first relapse of 31 months (range 2-108). The median Expanded Disability Status Scale (EDSS) score at the last follow up was 4 (range 1-9). Age at onset was an independent predictor of disability in the whole cohort of patients with NMOSD. For every 10-year increase in age at disease onset, the risk of developing an EDSS score of ≥4 increased by 34%. Patients who presented initially with a longitudinally extensive transverse myelitis (LETM) showed a higher risk to develop disability, compared to other clinical presentations (median time of 4 years versus 13 years). Late onset (LO-NMOSD) patients were likely to reach an EDSS score of 4 more quickly, compared to early onset (EO-NMOSD) (median time of 7 years versus 13 years). Higher median EDSS score at last follow up was observed in LO-NMOSD compared to EO-NMOSD (6 versus 2).

Conclusion: Increasing age at onset and LETM predict disability in AQP-4-IgG positive NMOSD patients.

Keywords: Age; Aquaporin-4; Late-onset NMOSD; Neuromyelitis optica spectrum disorder; Outcome.