1. In this systematic review and meta-analysis, history of concussion or mild traumatic brain injury was associated with a two-fold increased risk of suicide.
2. Although there was an association between the two, suicide remained a very rare cause of death for patients with concussion/mild traumatic brain injury.
Evidence Rating Level: 2 (Good)
Study Rundown: Concussions are the most common form of traumatic brain injury (TBI), and there is increasing evidence that they have long-term consequences. While the majority of patients have resolution of neurologic symptoms in the first week, approximately one quarter will have long term neuropsychiatric symptoms. Although systematic reviews have shown that severe TBI are linked with an increased risk of suicide, this study looked at concussion and mild TBI. In this large systematic review and meta-analysis, the risk of suicide was two times higher for patients with history of at least one concussion or mild TBI. This effect was larger in non-military personnel than in military personnel. The absolute risk of suicide for patients with concussion or mild TBI varied among studies and their respective follow up periods. Most studies that identified suicide attempts reported increased rates in patients with concussion/mild TBI.
While the large sample size (over 700,000 patients with concussion/mild TBI, 6,200,000 unaffected) supports this study’s findings, there are some limitations. Most notably, there was a high degree of statistical heterogeneity among the included cohort studies. These studies were also retrospective in nature, which limits the ability to establish causation.
In-Depth [systematic review and meta-analysis]: This was a systemic review and meta-analysis performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The primary exposure was concussion and/or mild traumatic brain injury (TBI), and the primary outcome was suicide. Secondary outcomes included suicide attempt and suicidal ideation. There were 17 studies included in the final study. This included 10 retrospective cohort studies, 5 cross-sectional studies, and 2 case-control studies for a total sample size of 718,572 with primary exposure and 6,255,552 without primary exposure. Of the above, 6 studies were included in analysis of suicide rates and all used ICD 8/9/10 codes to identify concussion/mild TBI. All used death certificates to identify suicide. Studies evaluating suicidal ideation and attempts used self-reported data. Patients with history of concussion/mild TBI had a relative risk of 2.03 (95% CI 1.47-2.80, p < 0.01) for suicide. Heterogeneity was high with I2=96%. Median follow up ranged from 3.6-12.3 years. The primary finding was more pronounced in non-military personnel (RR 2.36, 95% CI 1.64-2.40) then in military personnel (RR 1.46, 95% CI 0.80-2.58).
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