The Impact of Depression on Mortality Risk After Traumatic Brain Injury: A Traumatic Brain Injury Model Systems Study

OBJECTIVE: To examine whether depressive symptoms at 1 year postinjury are associated with all-cause mortality among individuals with moderate-to-severe traumatic brain injury (TBI) who received inpatient rehabilitation, accounting for sociodemographic, functional, and mental health factors. SETTING: Community. PARTICIPANTS: A total of 2812 individuals enrolled in the TBI Model Systems National Database with 1-year postinjury follow-up interviews between October 1, 2007, and October 1, 2013, and a follow-up within 5 years of injury. DESIGN: Prospective cohort study, using secondary analysis of longitudinal data. MAIN MEASURES: Depression (Patient Health Questionnaire-9) and all-cause mortality. RESULTS: The rate of high depressive symptom burden at 1-year follow-up was 28.5%, and the overall death rate was 8.8% across the study follow-up period. In age-adjusted models, higher depressive symptom burden at 1 year was associated with increased mortality risk; however, this association was progressively attenuated after adjustment for functional status and preinjury mental health variables and was no longer statistically significant in fully adjusted models. Sensitivity analyses using multiple imputation yielded similar results. CONCLUSION: Findings suggest that depressive symptom burden at 1 year postinjury is not independently associated with 5-year mortality after accounting for functional status and preinjury mental health history. Depression may, nonetheless, function as a clinically meaningful marker of broader vulnerability. Further research is warranted to explore whether targeting depression and functional recovery influence long-term survival after TBI.