Mortality risk following self‐harm in young people: a population cohort study using the Northern Ireland Registry of Self‐Harm

Background Self‐harm is a recognised predictor of suicide and is most common in those aged under 25 years. The aims of this study were to describe the characteristics of young people who present with self‐harm; quantify the risk of suicide and other causes of death during follow up, and to identify factors associated with mortality risk. Methods The Northern Ireland Registry of Self‐Harm (NIRSH) is a national registry capturing complete data on all presentations made to the 12 Emergency Departments (EDs) in Northern Ireland (NI). Data relating to self‐harm presentations registered in the NIRSH between 2012 and 2015 were linked to primary care registrations and death records up until 31st December 2018. Logistic regression was employed to examine the factors associated with self‐harm. Cox regression was used to estimate mortality risk following self‐harm and explore the associated risk factors. Results The cohort consisted of 390,740 individuals aged 10–24 years registered with a General Practitioner (GP) in NI. During follow‐up, 4,450 individuals presented with self‐harm. Rates of self‐harm were highest in females, those aged 20–24 years (ORadj = 3.53, 95% CI 3.28–3.80, p