Concussions associated with an increased risk of subsequent suicide

1. In a retrospective review of over 235 000 adults, the diagnosis of a concussion was associated with a significantly increased long-term risk of suicide compared to the general population.

Evidence Rating Level: 3 (Average)       

Study Rundown: Concussions, or mild traumatic brain injury (mTBI) affect over 1.74 million people in the United States annually and have been associated with significant short- and long-term neurological and psychiatric sequelae. Previous studies have demonstrated an association between mTBIs and subsequent risk of suicide within the military population. However, there has been limited data on this risk withinn the civilian population. The purpose of this large retrospective cohort study was to explore the relationship of mTBIs and subsequent suicide in the community setting.

The study reviewed the outcomes of over 235 000 adult patients with a diagnosis of mTBI over a 20-year period. At the conclusion of the study, adults who experienced an mTBI demonstrated a three-fold increase in the rate of subsequent suicides compared to the population average. This increased risk persisted after adjusting for patient’s demographics and was independent of a person’s past psychiatric conditions. Interestingly, adults who experience mTBI on a weekend demonstrate an even greater risk of subsequent suicides compared to patients who experience mTBI on a weekday. The results of this study highlight mTBIs as a potentially important risk factor in the assessment of self-harm. However, the study is limited by the retrospective nature, which did not analyze key factors which may affect the rate of suicide such as alcohol consumption or antidepressant use. Additional observational trials are warranted to analyze these potentially important associations.

Click to read the study in CMAJ

Relevant Reading: Does a history of mild traumatic brain injury increase suicide risk in veterans with PTSD?

In-Depth [retrospective cohort]: This was a study of 235 110 adult patients with a diagnosis of concussion in Ontario, Canada from 1992 to 2012. Patient information were collected from physician claims data from the Ontario Health Insurance Plan database. The major exclusion criteria were patients who were admitted to hospital within 2 days of injury. The outcome of interest was the frequency of suicide during the study period. Overall, the mean age was 41 years, 86% of the participants lived in an urban area, and 52% were male. At the conclusion of the trial, 667 suicides occurred in the study period, equating to a mortality rate of 31 deaths per 100 000 patients annually. This was 3 times greater than the population average in Ontario. Additionally, adults who experienced concussions over the weekend demonstrated significantly higher risk of suicide compared to adults who experienced concussions on a weekday (RR: 1.36; 95%CI: 1.14 to 1.64).

Image: CC/Wiki/Sander van der Wel 

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