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Investigating Unintentional Injury as a Risk Factor for Self-Harm

Research Highlight

Each year, adolescents go to emergency departments for both unintentional injury and deliberate self-harm. However, determining whether an adolescent’s accidental injury had suicidal or self-harm intent has long been recognized as a challenge. A better understanding of the association between unintentional injury and deliberate self-harm could inform and aid prevention and intervention efforts.

Past studies have found associations between having any nonfatal unintentional injury and risk of later self-harm. In a recent NIH-supported study , researchers investigated whether distinct subtypes of unintentional injury—or how the injury happened—have stronger associations with risk of future self-harm than others in adolescents. Identifying which adolescents with unintentional injury might be at elevated risk for future deliberate self-harm could help with targeting clinical assessment and intervention in emergency department settings.

For this study, the research team examined California state-level hospital data to identify adolescents 10­–19 years old who sought emergency department care for unintentional injury between 2006 and 2015. They categorized reasons for unintentional injury emergency department visits into drug poisonings, other poisonings, falls, suffocation injuries, cutting/piercing injuries, and strike injuries (being struck by or against an object).

The researchers investigated whether there were associations between the type of unintentional injury adolescents presented with in 2010 and both prior visits for deliberate self-harm (from 2006 to 2009), and later self-harm incidents (from 2010 to 2015).

The data showed that adolescents with drug-poisoning injuries consistently demonstrated the highest risk for self-harm, both before and after their unintentional injury emergency department visit. There were also significant positive associations between self-harm and unintentional injury visits for non-drug poisoning, cutting/piercing, and suffocation. When compared with adolescents who sustained a strike-injury, adolescents with all other subcategories of unintentional injury except injury by fall were at excess risk of deliberate self-harm. When those with unintentional injury by drug-poisoning, non-drug poisoning, suffocation, and cutting/piercing were compared to all adolescent patients treated in emergency departments, significant risk of deliberate self-harm remained but was not as elevated.

The researchers suggest that these findings could improve clinical practice by helping identify adolescent patients in emergency departments who are at risk of self-harm, but whose need for mental health services might otherwise go unrecognized. Emergency department providers could potentially incorporate information on prior unintentional injury and subtype of unintentional injury when diagnosing, treating, and referring injured adolescent patients to mental health providers. Further research on the causal relationships underlying the associations between unintentional injury and self-harm could lead to targeted clinical assessment and treatment of those causal factors, the researchers suggest, leading to improved clinical interventions.


Phillips, D., Lidón-Moyano, C., Cerdá, M, Gruenwald, P., Goldman-Mellor, S. (2020). Association between unintentional injuries and self-harm among adolescent emergency department patients. General Hospital Psychiatry. DOI: 10.1016/j.genhosppsych.2020.03.008