Visual abstract: https:/ / www. cmaj. ca/ press-release-4-nov-19

Teens who visit the emergency department for self-harm injuries are at significant risk of repeat self-harm and suicide, and of incurring increased health costs over the following five years, according to a new study in CMAJ (Canadian Medical Association Journal).

Youth who self-harmed were five times more likely to have repeat visits to the emergency department, three times more likely to die from any cause and eight times more likely to die from suicide than youth who did not self-harm and who were matched on sex, age, and psychiatric and medical diagnoses.

"Among adolescents who presented after self-harm, and who later had recurrent admissions for self-harm, serious and complex mental conditions were common, most prominently anxiety and mood disorders, as well as substance abuse issues, and concussion or traumatic brain injury," writes Dr. William Gardner, CHEO Research Institute and the University of Ottawa, Ottawa, Ontario, with coauthors.

The study included data on 403 805 youth aged 13-17 years who visited emergency departments in Ontario, Canada's largest province, between 2011 and 2013. Of the total number of youth, 5832 visited the emergency department following self-harm, and 5661 of them were matched with 10 731 control participants who visited the emergency department for other reasons. Youth who presented with self-harm, were older (by about a year) than controls and more likely to be female (79% vs. 48%).

Emergency department visits for self-harm have more than doubled in Ontario over the last 10 years -- a worrying trend.

"Over and above an elevated suicide risk, having an emergency department visit related to self-harm is a predictor for recurrent visits to the emergency department and greater use of health services," write the authors.

Almost one-third of the adolescents with visits for self-harm were either readmitted to hospital or had subsequent emergency department visits, which resulted in higher costs to the system. The adolescents with self-harm had $11 000 higher health system costs over five years than the matched control patients. The authors noted that this was a conservative estimate on the cost difference.

"Our results suggest that adolescents who present at the emergency department after self-harm would benefit from assessment for mental health or substance misuse disorders," write the authors.

Although youth with self-harm were more likely to die by suicide, suicide was nevertheless an uncommon outcome (occurring in less than 1% of adolescents who presented to the emergency department following self-harm).

The authors call for research into better ways to assess mental health in the emergency department and to connect emergency departments with community mental health services.

"If adolescents presenting with self-harm have mental health or substance misuse issues, they should be connected to evidence-based community services for treatment," the authors conclude.

The research was funded by a grant from the Scotiabank Foundation to two of the authors.

"Health outcomes associated with emergency department visits by adolescents for self-harm: a propensity-matched cohort study" is published November 4, 2019

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