Abstract

Background: Optic neuritis (ON) can be an initial manifestation of neuromyelitis optica spectrum disorder (NMOSD) associated with aquaporin 4-antibody (AQP4-Ab) or myelin oligodendrocyte glycoprotein antibody (MOG-Ab)-associated disease (MOGAD). Additionally, both diseases may have overlapping paraclinical and radiological features. These diseases may have different outcomes and prognoses. We aimed to compare clinical outcomes and prognostic features of patients with NMOSD and MOGAD presenting ON as first attack, from different ethnic groups in Latin America. Methods: We conducted a retrospective observational multicenter study in patients from Argentina (n = 61), Chile (n = 18), Ecuador (n = 27), Brazil (n = 30), Venezuela (n = 10) and Mexico (n = 49) with MOGAD or NMOSD related ON. Predictors of disability outcomes at last follow-up, namely visual disability (Visual Functional System Score >= 4), motor disability (permanent inability to walk further than 100 m unaided) and wheelchair dependence based on EDSS score were evaluated.Results: After a mean disease duration of 42.7 (+/- 40.2) months in NMOSD and 19.7 (+/- 23.6) in MOGAD, 55% and 22% (p>0.001) experienced permanent severe visual disability (visual acuity from 20/100 to 20/200), 22% and 6% (p = 0.01) permanent motor disability and 11% and 0% (p = 0.04) had become wheelchair dependent, respectively. Older age at disease onset was a predictor of severe visual disability (OR=1,03 CI95%1.01-1.05, p = 0.03); older age at disease onset (OR=1,04 CI95%1.01-1.07, p = 0.01), higher number of relapses (OR=1,32 CI95%1.02-1.71, p = 0.03) and rituximab treatment (OR=0,36 CI95%0.14-0.90, p = 0.02) were predictors of permanent motor disability, whereas ON associated with myelitis at disease onset was a predictor of wheelchair dependency (OR=4,16, CI95%1.23-14.08, p = 0,02) in NMOSD patients. No differences were found when evaluating distinct ethnic groups (Mixed vs. Caucasian vs. Afro-descendant)Conclusions: NMOSD was associated with poorer clinical outcomes than MOGAD. Ethnicity was not associated with prognostic factors. Distinct predictors of per-manent visual and motor disability and wheelchair dependency in NMOSD patients were found.