The Serious Self-Harm Risk of “Mixed Presenters,” People Who Presented to New Zealand Emergency Departments for Self-Harm and Other Reasons: A Cohort Study

The objective of this study was to investigate if “Mixed Presenters,” people who present to emergency departments at least twice within 28 days, once for self-harm and once for another reason (any order), have an increased risk of subsequent serious self-harm compared to self-harm only repeat presenters. Self-harm coded emergency department data from the Multi-level Intervention for Suicide Prevention (MISP) study was utilized to identify people with at least two presentations to one of eight District Health Boards between 2010 and 2012. First eligible presentation pairs determined their “Mixed Presenter” or “Self-harm Only Presenter” status. The sample was linked to admission and mortality datasets. Survival analysis over the 30-month timeframe was used to determine which presenter group was at higher risk of serious self-harm. Mixed Presenters (n = 1,544), four times more common than Self-harm Only Presenters (n = 377), had an estimated 60% reduced risk of serious self-harm compared to Self-harm Only Presenters. Compared to men, women had a 3.5 times (HR 3.53, 95% CI 2.47–5.06) increased risk. Having an urgent triage code allocated at the index presentation and being admitted at that index presentation were associated with increased serious self-harm risk for Self-harm Only Presenters compared to Mixed Presenters. This study confirms that two presentations for self-harm within a short timeframe indicate high risk of serious self-harm in the future. As men often die following single attempts, and Mixed Presenters may transition to being Self-harm Only Presenters, each presentation for self-harm requires serious attention.