The aim of this study was to describe presentations to hospital as a result of self-harm or suicidal ideation and to examine patterns of repetition.

Presentations made to hospital emergency departments in Northern Ireland following self-harm and ideation between April 2012 and March 2017 were recorded by the Northern Ireland Registry of Self-harm. Person-based rates per 100,000 were calculated using national population estimates. Risk of repeat attendance to hospital was examined using Kaplan-Meier analyses.

A total of 62,213 presentations to emergency departments following self-harm or with ideation were recorded. The rate of self-harm was more than twice the rate of hospital-presenting ideation. Rates of ideation were higher among men, and both self-harm and ideation rates peaked for girls aged 15–19 and men aged 20–24 years. The cumulative probability of repeat attendance to hospital was higher following ideation (52% after 12 months), primarily because 12% of ideation presentations were followed by a subsequent self-harm presentation, whereas 4% of self-harm presentations were followed by ideation.

Our findings indicate that hospital presenters with ideation are at high risk of future self-harm. The transition from ideation to suicidal behaviour is important to consider and research could inform effective and early intervention measures.