Risk of Depression after Traumatic Brain Injury in a Large National Sample

Depression is associated with poorer recovery after traumatic brain injury (TBI), yet awareness of depression risk post-TBI among providers and patients is low. The aim of this study was to estimate risk of depression post-TBI among adults 18 years of age and older and to identify risk factors associated with developing depression post-TBI. We conducted a retrospective, matched cohort study using claims data for privately insured and Medicare Advantage enrollees in a large U.S. health plan. Adults 18 years of age diagnosed with TBI (n=207,354) with 12 months continuous insurance coverage pre-TBI and 24 months post-TBI were matched to controls without TBI (n=414,708). We identified the presence of depression on any in- or outpatient claim occurring during the study period (both before and after TBI). Of the initial 622,062 individuals, 62,963 (10%) had depression pre-TBI and were excluded from incidence calculations. Incidence of depression post-TBI was 79.5 (95% confidence interval [CI], 78.5,80.5) per 1,000 person-years compared to 33.5 (95% CI, 33.1,34.0) per 1,000 person-years for those without TBI. The adjusted hazard ratio for depression post-TBI was 1.83 (95% CI, 1.79,1.86). We observed effect modification by sex and age, with males and older adults at increased risk. History of neuropsychiatric disturbances pre-TBI was the strongest predictor of depression post-TBI. Risk of depression increases substantially post-TBI. Groups at increased risk include those with a history of neuropsychiatric disturbances, older adults, and men. This study highlights the importance of long-term monitoring for depression post-TBI.