BACKGROUND: Understanding the economic cost of self-harm is essential for evaluating intervention cost-effectiveness and guiding funding allocation and service planning.

AIMS: To estimate the cost associated with self-harm presentations to hospital emergency departments and investigate key predictors of cost.

METHOD: Data on presentations to hospital for self-harm in all Irish emergency departments were analysed for 2018 and 2019. Costs of hospital treatment following self-harm were identified (in 2019 euros) using top-down and bottom-up approaches. The perspective taken was that of the health service. Factors associated with costs were investigated using generalised linear models.

RESULTS: There were 25 053 self-harm presentations from 2018 to 2019. The average annual cost of self-harm was approximately €26.5 million; almost half of the total cost was due to repeat self-harm presentations (47.3%). The mean cost per presentation was €2117 (s.d. €1845), which incorporates acute hospital costs (mean €2067, s.d. €2127) and those of initial aftercare (mean €50, s.d. €69). Psychiatric and medical admissions were associated with highest costs, three times that of presentations resulting in emergency department discharge (incidence rate ratio (IRR) 3.01, 95% CI 2.72-3.36 and IRR 2.88, 95% CI 2.72-3.36, respectively). Other factors associated with higher costs included older age, emergency department medical assessment unit admission, receiving a psychosocial assessment and self-harm involving a firearm. Demographic and clinical predictors of cost varied according to care pathway.

CONCLUSIONS: Significant costs associated with repeat attendances and hospital admission provide evidence for investment in emergency department services providing comprehensive care for those presenting with self-harm, as well as in community-based mental health services.