Risk of subsequent self-harm, suicide attempts and suicide following a first hospital-treated self-harm episode among young people: a population-based cohort study.

backgroundSelf-harm in young people is associated with elevated risks for subsequent self-harm, suicide attempts and suicide, particularly during the first year. Yet the trajectory across sex, age and self-harm methods remains poorly understood.

objectiveTo estimate risk for subsequent self-harm, suicide attempts and suicide following a first hospital-treated self-harm event in young people.

methodsThis study included 77 647 individuals (57.0% female) whose first hospital-treated (ie, within inpatient or outpatient specialised healthcare) self-harm episode occurred between ages 10-24 years during 1973-2019. We estimated cumulative incidence and incidence rate for subsequent self-harm, suicide attempts and suicide at 1 month, 3 months and 1 year following the initial episode.

findingsWithin 1 year, the cumulative incidence was 17.3% (95% CI 17.0 to17.5) for subsequent self-harm, 8.3% (8.1 to 8.5) for suicide attempt and 0.3% (0.2 to 0.3) for suicide. The highest risks occurred in the first month: 8.4% (8.2 to 8.6) for self-harm, 2.9% (2.8 to 3.0) for suicide attempt and 0.04% (0.03 to 0.05) for suicide. In the first month, the incidence rate of self-harm was 2.97 per 1000 person-days (2.90 to 3.05), falling to 0.55 (0.54 to 0.56) over the year. The suicide attempt rate declined from 0.98 (0.94 to 1.02) to 0.24 (0.24 to 0.25) and the suicide rate from 0.013 (0.009 to 0.019) to 0.007 (0.006 to 0.008). Males exhibited the highest suicide risk and females the highest attempts risk. First-month self-harm risk was greatest among males and children aged 10-12.

conclusionsThe month following a self-harm episode is marked by an elevated risk of subsequent self-harm, suicide attempts and suicide, yet risk remains elevated over the full year. CLINICAL IMPLICATIONS: These findings underscore the need for both acute and sustained prevention efforts. Special attention should be given to males and children aged 10-12 presenting with self-harm of ambiguous intent, as their risk of repetition may otherwise go unrecognised.