Multiple sclerosis among service members of the active and reserve components of the U.S. Armed Forces and among other beneficiaries of the Military Health System, 2007-2016.

During 2007-2016, a total of 2,031 active component service members received incident diagnoses of multiple sclerosis (MS), for an overall unadjusted incidence rate of 14.9 cases per 100,000 p-yrs. The average overall unadjusted rate among reserve/guard members during this surveillance period was 6.9 cases per 100,000 persons. In both components, women had a higher overall incidence of MS than men across all race/ethnicity groups. Overall rates of MS were highest among non-Hispanic black service members. Crude annual incidence rates among active component members decreased slightly during 2007-2016, while rates among reserve/guard members were relatively stable. Among active component members, the annual female-to-male incidence ratios decreased during the 10-year period (3.7:1 in 2007 to 2.5:1 in 2016). Annual numbers of incident cases of MS decreased among non-service member Military Health System beneficiaries during this period. The median age at MS case-defining diagnosis was 32 years among active component members, 37 years among reserve/guard members, and 48 years among non-service member beneficiaries. The median time intervals between initial presentation and case-defining MS-related encounter ranged from 15 days among reserve/guard component members to 20 days among active component service members. This study makes a useful contribution to the literature on temporal changes in the incidence of MS by sex and race/ethnicity.