BACKGROUND: Factors contributing to suicidal behaviour are complex and multi-faceted. This study took an ecological approach to examine the association between area-level factors and rates of self-harm in Northern Ireland.

METHODS: Data on self-harm presentations to emergency departments (EDs) were obtained from the Northern Ireland Self-harm Registry. The study included residents of Northern Ireland aged 16-64 years. Deprivation was measured using the Northern Ireland Multiple Deprivation Measure 2017. Population density and social fragmentation were calculated using measures from the 2011 census. Associations between area-level factors and self-harm rates were explored using negative binomial regression.

RESULTS: Between 2013 and 2015, 14 477 individuals aged 16-64 years presented to EDs in Northern Ireland following self-harm. The rate of self-harm was 472 per 100 000 and was higher for male residents (478 vs. 467). Self-harm rates were highest in urban areas-680 per 100 000 in Belfast City and 751 per 100 000 in Derry City. Rates of self-harm in Northern Ireland were more than four times higher in the most deprived areas. A positive association with rates of self-harm held for the deprivation domains of employment, crime, education, health and income. There was a moderate association with population density. Some gender differences emerged, with associations with male rates of self-harm more pronounced.

CONCLUSION: These findings indicate that self-harm rates are highest for those residing in highly deprived areas, where unemployment, crime and low level of education are challenges. Community interventions tailored to meet the needs of specific areas may be effective in reducing suicidal behaviour.