Risk of suicide after a concussion

Abstract

Background: Head injuries have been associated with subsequent suicide among military personnel, but outcomes after a concussion in the community are uncertain. We assessed the long-term risk of suicide after concussions occurring on weekends or weekdays in the community.

Methods: We performed a longitudinal cohort analysis of adults with diagnosis of a concussion in Ontario, Canada, from Apr. 1, 1992, to Mar. 31, 2012 (a 20-yr period), excluding severe cases that resulted in hospital admission. The primary outcome was the long-term risk of suicide after a weekend or weekday concussion.

Results: We identified 235,110 patients with a concussion. Their mean age was 41 years, 52% were men, and most (86%) lived in an urban location. A total of 667 subsequent suicides occurred over a median follow-up of 9.3 years, equivalent to 31 deaths per 100,000 patients annually or 3 times the population norm. Weekend concussions were associated with a one-third further increased risk of suicide compared with weekday concussions (relative risk 1.36, 95% confidence interval 1.14-1.64). The increased risk applied regardless of patients' demographic characteristics, was independent of past psychiatric conditions, became accentuated with time and exceeded the risk among military personnel. Half of these patients had visited a physician in the last week of life.

Interpretation: Adults with a diagnosis of concussion had an increased long-term risk of suicide, particularly after concussions on weekends. Greater attention to the long-term care of patients after a concussion in the community might save lives because deaths from suicide can be prevented.

Figure 1:

Long-term risk of suicide, shown as the cumulative incidence of suicide after concussion (p < 0.001). This p value is based on the log-rank test comparing the weekend concussion group with the weekday concussion group; p values comparing study patients with the population norm were more extreme and are not reported. The main findings showed progressive differences in suicide risk after the initial concussion.

Figure 2:

Risk of suicide by day of initial concussion. Error bars denote the upper standard error of the estimates. Horizontal red line shows the population norm of 9 per 100 000. The main findings showed a consistent increase in the long-term risk of suicide after concussion on a weekday, with a further increase after concussion on a weekend.