Risk of suicide after a concussion

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.Suicide is a leading cause of death in both military and community settings.¹ During 2010, 3951 suicide deaths occurred in Canada² and 38 364 in the United States.³ The frequency of attempted suicide is about 25 times higher, and the financial costs in the US equate to about US$40 billion annually.⁴ The losses from suicide in Canada are comparable to those in other countries when adjusted for population size.⁵ Suicide deaths can be devastating to surviving family and friends.⁶ Suicide in the community is almost always related to a psychiatric illness (e.g., depression, substance abuse), whereas suicide in the military is sometimes linked to a concussion from combat injury.^7–10Concussion is the most common brain injury in young adults and is defined as a transient disturbance of mental function caused by acute trauma.¹¹ About 4 million concussion cases occur in the US each year, equivalent to a rate of about 1 per 1000 adults annually;¹² direct Canadian data are not available. The majority lead to self-limited symptoms, and only a small proportion have a protracted course.¹³ However, the frequency of depression after concussion can be high,^14,15 and traumatic brain injury in the military has been associated with subsequent suicide.^8,16 Severe head trauma resulting in admission to hospital has also been associated with an increased risk of suicide, whereas mild concussion in ambulatory adults is an uncertain risk factor.^17–20The aim of this study was to determine whether concussion was associated with an increased long-term risk of suicide and, if so, whether the day of the concussion (weekend v. weekday) could be used to identify patients at further increased risk. The severity and mechanism of injury may differ by day of the week because recreational injuries are more common on weekends and occupational injuries are more common on weekdays.^21–27 The risk of a second concussion, use of protective safeguards, propensity to seek care, subsequent oversight, sense of responsibility and other nuances may also differ for concussions acquired from weekend recreation rather than weekday work.^28–31 Medical care on weekends may also be limited because of shortfalls in staffing.³²