Health outcomes associated with emergency department visits by adolescents for self-harm: a propensity-matched cohort study.

<bold>Background: </bold>Self-harm is increasing among adolescents, and because of changing behaviours, current data are needed on the consequences of self-harm. We sought to investigate the trends related to hospital presentation, readmission, patient outcome and medical costs in adolescents who presented with self-harm to the emergency department.<bold>Methods: </bold>We used administrative data on 403 805 adolescents aged 13-17 years presenting to Ontario emergency departments in 2011-2013. Adolescents with self-harm visits were 1:2 propensity matched to controls with visits without self-harm, using demographic, mental health and other clinical variables. Five years after the index presentation, hospital or emergency department admission rates for self-harm, overall mortality, suicides and conservative cost estimates were compared between the 2 groups.<bold>Results: </bold>Of 5832 adolescents who visited Ontario emergency departments in 2011-2013 after self-harm (1.4% of visits), 5661 were matched to 10 731 adolescents who presented for reasons other than self-harm. Adolescents who presented with self-harm had a shorter time to a repeat emergency department or hospital admission for self-harm (hazard ratio [HR] 4.84, 95% confidence interval [CI] 4.44-5.27), more suicides (HR 7.96, 95% CI 4.00-15.86), and higher overall mortality (HR 3.23, 95% CI 2.12-4.93; p < 0.001). The positive predictive value of self-harm-related emergency department visits for suicide was 0.7%. Adolescents with self-harm visits had mean 5-year estimates of health care costs of $30 388 compared with $19 055 for controls (p < 0.001).<bold>Interpretation: </bold>Adolescents with emergency department visits for self-harm have higher rates of mortality, suicide and recurrent self-harm, as well as higher health care costs, than matched controls. Development of algorithms and interventions that can identify and help adolescents at highest risk of recurrent self-harm is warranted. [ABSTRACT FROM AUTHOR]