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  • Large population study examines rate of optic neuritis conversion to MS

    Neuro-Ophthalmology/Orbit

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    This population-based study evaluated the incidence of optic neuritis and risk of conversion to multiple sclerosis (MS) among people from South Korea.

    Study design

    The authors used the South Korean National Health Insurance system to identify 44,700,564 children (age≤14 years) and adults (age 15 to 65 years). The main outcome measures were prevalence and incidence of optic neuritis and conversion rate to MS between 2010 and 2016.

    Outcomes

    Optic neuritis was noted in 531 pediatric and 7,183 adult patients. The annual incidence of neuritis among the pediatric and adult populations was 1.04 per 100,000 children and 3.29 per 100,000 adults, respectively. During the study period, the conversion rate to MS was 13.8% in the pediatric population and 11.4% in the adult population. Nearly all patients (99.2%) with optic neuritis were treated with intravenous corticosteroids. Approximately 38% of patients with neuromyelitis optica (NMO) underwent plasmapheresis.

    Limitations

    A limitation with any big-data study is the dependence on diagnosis codes and the lack of access to medical charts to confirm diagnosis. This study could not determine the aquaporin 4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) status, which are biomarkers for NMO and MOG-IgG associated disorders, respectively. These are demyelinating diseases that are separate from MS despite some overlapping characteristics, including the propensity toward optic neuritis. Although the rates of NMO and acute disseminated encephalomyelitis (ADEM) were determined, they will not accurately capture the percentage of patients that have AQP4-IgG and MOG-IgG.

    Clinical significance

    Despite the limitations, this is one of the largest population-based studies on optic neuritis, especially in an Asian cohort. These findings corroborate previous studies indicating that the risk of MS is lower in Asians than in Caucasians. It found that the South Korean incidence of pediatric optic neuritis was higher than reported in prior Caucasian studies, while incidence of adult optic neuritis was similar or slightly lower. Future studies will be required to determine the incidence of AQP4-IgG and MOG-IgG optic neuritis in South Korea and how it impacts the relative frequency of MS, NMO and ADEM.