Neuromyelitis Optica Spectrum Disorder (NMOSD) is a devastating neurological disorder of particular importance to the U.S. Military because it is highly disabling, often rapidly causing complete or partial blindness and/or paralysis. NMOSD can permanently disqualify a service-member from continued duty, leading not only to personal disability for the member, but degraded capability for the Force.
The objective of this study is to define the epidemiology of NMOSD among U.S. Military Active Duty Service Members (ADSM). Specifically, we aimed to understand the prevalence, demographics, disease subtypes (seropositive (SP), seronegative (SN), anti-MOG), and disease associations among ADSM diagnosed with NMOSD between 2004 and 2019.
A U.S. Military Health Systems database (MHS Mart, M2) was searched for outpatient clinic encounters that listed ICD9 (341.0) and ICD10 (G36.0) codes for NMOSD between 2004 and 2019. ADSM with at least one encounter listing an ICD9 or ICD10 code for NMOSD were included in the study. Relevant information was then abstracted systematically from clinical electronic medical records systems (AHLTA, HAIMS, JLV). A clinical database was generated. Data was analyzed using standard statistical methods. This project was reviewed and approved by the Walter Reed National Military Medical Center IRB and the University of Utah/SLC VA IRB.
118 patients were identified. Forty Seven (48) met 2015 criteria for NMOSD. Of these, 28 were women. There were 34 SP, 10 SN, and 4 anti-MOG patients. The average age at time of disease onset was 36 years for women, and 40 years for men. Age of onset by serostatus was 40 years for SP, and 32 years for SN patients. Distribution by race was as follows: Black: 25, Caucasian: 16, Other or Unknown: 4, Hispanic: 2, Asian / Pacific Islander: 1. SP patients presented with longitudinally extensive transverse myelitis (LETM) (15), optic neuritis (ON) (11), area postrema syndrome (4), or multifocal symptoms (3). SN patients presented with LETM (5), ON (2), or multifocal symptoms (2). Co-existing autoimmunity was seen in 19 SP patients and 1 SN patient. The most common co-existing autoimmune disease was Sjogren Syndrome (7). The incidence of NMOSD in the US Military ranged from 0 – 0.7 cases per 100,000 ADSM for the period in question.
This study clarifies the epidemiology of NMOSD within the US Military during the years 2004-2019. It demonstrates disease burden based on race and gender and confirms an association of co-existing autoimmunity among patients with SP NMOSD. Further research assessing pre-symptomatic sera for AQP4-IgG from the Department of Defense Serum Repository in this cohort will hopefully shed further light on this disease.