Incidence of Optic Neuritis and the Associated Risk of Multiple Sclerosis for Service Members of U.S. Armed Forces

Introduction Optic neuritis (ON), an acute inflammation of the optic nerve resulting in eye pain and temporary vision loss, is one of the leading causes of vision-related hospital bed days in the U.S. Military and may be a harbinger of multiple sclerosis (MS). We developed a case identification algorithm to estimate incidence rates of ON and the conversion rate to MS based on a retrospective assessment of medical records of service members (SMs) of the U.S. Armed Force. Materials and Methods Electronic medical records (EMRs) from 2006 to 2018 in the Defense Medical Surveillance System were screened using the case identification algorithms for ON and MS diagnosis. The incidences rates of ON were calculated. The rates of conversion to MS was modeled using the Kaplan–Meier survival analysis. Results The overall incidence rate of ON was 8.1 per 100,000 from 2006 to 2018. Females had a rate (16.9 per 100,000) three times higher than males. Most (68%) of subsequent diagnoses of MS were made within 1 year after diagnosis of ON. The overall 5-year risk of progression to MS was 15% (11%–16% for 95% CI). The risk of conversion to MS in females was significantly higher than in males. Conclusions We developed an efficient tool to explore the EMR database to estimate the burden of ON in the U.S. Military and the MS conversion based on a dynamic cohort. The estimated conversion rates to MS feeds into inform retention and fitness-for-duty policy in these SMs.