Physical and Behavioral Health Diagnoses and Comorbidities Associated with Transition from Military Health System to Veterans Health Care Among Post-9/11 Veterans

Background and Purpose: Post-9/11 veterans have high rates of disability and significant health care needs that persist during the military-to-veteran transition and after military separation. The military-to-veteran transition increases vulnerability for new and worsening physical and psychiatric conditions and psychosocial problems as veterans reintegrate into civilian life. Among post-9/11 veterans, this study identified military characteristics, diagnoses, multimorbidities, and intersecting social identities associated with transitioning from Military Health System (MHS) to Veterans Health Administration (VHA) care after military separation.

Methods: A retrospective cohort study was conducted from the Long-Term Impact of Military-Relevant Brain Injury Consortium-Chronic Effects of Neurotrauma Consortium Phenotype Study. Population-level data were extracted from MHS and VHA electronic health data from FY 2000-2020. Eligible participants were post-9/11 veterans who received at least three years of MHS care and separated from military service before FY 2017 (October 1, 2016). The primary outcome was transition from MHS to VHA care after military separation. Covariates included demographic, military, and deployment characteristics at military separation; physical, mental health, and substance use diagnoses and comorbidities two years before military separation. Military separation date was the index date. Logistic regression was conducted to estimate odds of transitioning to VHA care after military separation. Age x sex, race and ethnicity x sex, and age x race and ethnicity interactions were also examined.

Results: Among 1,594,869 post-9/11 veterans, 81.9% were male, 54.2% Active duty, and 48.8% were ages 25-34; 78% transitioned to VHA care. Of those, 70% had combat deployments, 17.5% were women, and 38.5% were Black, Hispanic, Asian/Pacific Islander, or Native American. Pain (55.8%) and smoking (40.8%) were the most prevalent conditions two years before military separation. Psychiatric diagnoses and substance use disorder, traumatic brain injury, and pain comorbidities significantly increased odds of transitioning to VHA care. Having a polytrauma clinical triad (PCT, comorbid traumatic brain injury, posttraumatic stress disorder, and pain; OR: 5.45, 95% CI: 4.77-6.23) diagnosis also increased odds of transitioning to VHA care. Suicidality was not associated with higher odds of transitioning to VHA care. Racial and ethnic minority men (ORs: 1.17-2.02) transitioned more often than White men. Black, Hispanic, and Native American women (ORs: 1.35-2.52) transitioned more often than White women. National Guard (OR: 2.23; 95% CI: 2.19-2.27) and Reserve (OR: 1.35; 95% CI: 1.34-1.37) members transitioned more often than Active-duty members.

Conclusions and Implications: Post-9/11 veterans diagnosed with psychiatric conditions and substance use disorder, traumatic brain injury, and pain comorbidities had higher odds of transitioning to VHA care after military separation. Intersectionality significantly influenced MHS to VHA care transitions among post-9/11 veterans, especially for racial and ethnic minority men and women veterans. Although post-9/11 veterans with multimorbidity experienced a high frequency of MHS-VHA care transitions, gaps may exist in the MHS-VHA care continuum for veterans who received treatment for suicidality two years prior to military separation. Study findings have implications for targeted care coordination for veterans at higher risk for suicide and health equity strategies for Active-duty members and racial and ethnic minorities transitioning from military service to civilian communities.