Multiple sclerosis and neuromyelitis optica after optic neuritis: A nationwide cohort study in Taiwan

The long-term outcome of optic neuritis (ON) is heterogeneous, and it appears to vary among different populations. Identification of determinants of natural history of ON would be helpful in therapeutic planning and prognostication, while relevant investigations in Asian patients were less reported. This study aims to clarify whether comorbidities and treatment in ON patients are associated with differential risks of subsequent development of multiple sclerosis (MS) or neuromyelitis optica (NMO) in Taiwan.

We conducted the nationwide population-based cohort study using data from Taiwan's National Health Insurance Research Database. Incident ON cases during 2003~2014 were followed until the end of 2015. Pediatric and adult sub-cohorts were examined separately. The associations between immune-related comorbidities or treatment and outcomes were analyzed using Cox proportional hazards models.

A total of 11,923 adult and 1365 pediatric ON patients were enrolled. The rates of subsequent development of MS were 2.7% for adult and 3.1% for pediatric ON with median follow-up duration of 6.3 and 7.3 years respectively, while 1.2% of pediatric and adult ON evolved to NMO. Comorbid systemic lupus erythematosus was associated with increased risks of subsequent development of MS in adult (adjusted hazard ratio [aHR], 2.80; 95% CI, 1.04-7.49) and pediatric ON patients (aHR, 21.65; 95% CI, 1.29-363.4). Adult ON patients were at increased risks of NMO if comorbid with myasthenia gravis (aHR, 9.13; 95% CI, 1.20-69.45) or Sjogren's syndrome (aHR, 4.71; 95% CI, 1.74-12.76).

ON could be the sentinel event linking several peripheral autoimmune comorbidities to distinct forms of central nervous system demyelination.