Sex Differences in Early/Unplanned Separation Among US Service Members With a History of Mild Traumatic Brain Injury

Area of Science:

• Neuroscience
• Military Medicine
• Public Health

Background:

• Mild traumatic brain injury (mTBI) is a common injury in military personnel.
• Early/unplanned (E/U) separation from service following mTBI can have significant long-term health and socioeconomic consequences.
• Existing research has not fully elucidated sex-based differences in E/U separation rates after mTBI.

Purpose of the Study:

• To determine the incidence of E/U separations within two years of mTBI diagnosis in active duty service members.
• To investigate whether sex influences the risk (hazard) of E/U separation after mTBI.
• To identify specific reasons for E/U separation that may differ between male and female service members.

Main Methods:

• Retrospective cohort study utilizing electronic health records from the Military Health System (MHS).
• Inclusion of 75,730 active duty service members diagnosed with mTBI between January 2011 and January 2018.
• Application of cause-specific Cox proportional hazards models, with sex at birth as the primary predictor variable.

Main Results:

• The overall incidence of E/U separation within two years post-mTBI was 13.7% (14.2% in men, 11.0% in women).
• Disability and misconduct were the most frequent reasons for E/U separation.
• Female service members exhibited lower adjusted hazards for overall E/U separation, disability, misconduct, and poor performance compared to males, but higher hazards for separations due to other medical circumstances.

Conclusions:

• Significant sex-based differences exist in the hazards of E/U separation following mTBI among service members.
• The distinct patterns of separation suggest unique challenges faced by men and women after mTBI.
• Further research is warranted to explore the underlying reasons for these sex-based disparities and their impact on long-term outcomes.