Clinical features and prognosis of late-onset neuromyelitis optica spectrum disorders in a Latin American cohort

Background We aimed to assess the clinical, paraclinical, imaging and prognostic features of patients with late-onset neuromyelitis optica spectrum disorder (LO-NMOSD; >= 50 years at disease onset) LO-NMOSD, compared with early onset-NMOSD (EO-NMOSD, <= 49 years at disease onset), in Latin American (LATAM). Methods We retrospectively reviewed the medical records of patients with NMOSD, as defined using the 2015 validated diagnostic criteria. We included patients from Argentina, Brazil and Venezuela. They were divided into: LO-NMOSD and EO-NMOSD and comparison among the groups were performed. Results Among these 140 NMOSD patients, 24 (17.1%) were LO-NMOSD; 64% were positive for aquaporin-4 antibodies; and 41.5% of this population cohort was non-Caucasian. Severe disability [expanded disability status scale (EDSS) >= 6] at the last follow-up and presence of comorbidities were significantly associated with LO-NMOSD, compared with EO-NMOSD. LO-NMOSD patients had a shorter median time to EDSS >= 4 than EO-NMOSD patients (46 vs. 60 months; log-rank test p = 0.0006). Furthermore, we observed a positive correlation between age at onset and EDSS score at the last follow-up (Spearman r = 0.34, p < 0.0001). Conclusion LO-NMOSD patients from LATAM developed early severe disability, compared with EO-NMOSD. Therefore, age at onset could have important implications for the long-term prognosis of NMOSD patients.