Risk of repeat self-harm and suicide death following an episode of hospital self-harm presentation among adolescents and young adults

Background: Self-harm is a critical issue affecting young people which could result in adverse outcomes including repeat episodes and suicide. In this study, we aimed to estimate the short-term and long-term risk of repeat self-harm and subsequent suicide death following self-harm presentations among adolescents and young adults. Methods: Using linked data from the New South Wales (NSW) Emergency Department Data Collection (EDDC), the NSW Admitted Patient Data Collection (APDC), and cause of death unit record file (COD-URF), we collected all self-harm presentations to emergency departments and/or hospitals and suicide deaths between 2012 and 2019 in NSW, Australia. We used survival analysis models to estimate the incidence of repeat self-harm and suicide by time since the index self-harm and relative risks by sex, type of hospital presentation and count of self-harm records. Results: In total, we identified 81,133 self-harm episodes among 48,547 individuals aged 10–29 years. Of 48,547 individuals who engaged in an index self-harm during the study period, 39.5 % (19,180) were aged between 15 and 19 years. The incidence of both repeat self-harm and suicide were highest in the year following the index self-harm presentation (repeat self-harm: 188.84 per 1000 person-years; suicide: 3.30 per 1000 person-years) and declined to 14.51 and 0.28 per 1000 person-years after five years. Among individuals indexed for self-harm at 15–29 years, males and those who were admitted to hospital for the index self-harm had the highest risk of both subsequent repeat self-harm and suicide death and those with 2 or more self-harm presentation records had the higher risk for subsequent suicide death. Conclusion: Adolescents and young adults with self-harm presentations were at a high risk of subsequent repeat self-harm and suicide death, especially the first year after presentations. Youth-specific early intervention and long-term management should be delivered accordingly, especially for those at early adolescence.