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Identifying deliberate self-harm in emergency department data

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by Jennifer Bethell and Anne E. Rhodes



Emergency department data offer more representative deliberate self-harm (DSH) information than inpatient admission data. However, emergency department data may underestimate DSH if some records coded "undetermined" (UD) represent DSH.

Data and methods

The data are from the National Ambulatory Care Reporting System. A total of 24,437 Ontario emergency department records for 2001/2002, coded DSH or UD, were analyzed. Age- and sex-specific estimates were compared under alternative DSH definitions.


For every two emergency department presentations coded DSH, another was coded UD. Cut/Pierce injuries and poisonings coded UD appeared to represent DSH more often than did UD presentations involving other injuries. Among index episodes coded UD, the rate of subsequent DSH presentation was nearly ten times higher when cut/pierce injury or poisoning was involved. Including presentations coded UD among those coded DSH increased the 12-month cumulative incidence of DSH by up to 60%.


Some emergency department presentations coded UD likely represent DSH.


Worldwide, suicide is among the three leading causes of death of people aged 15 to 44. In Canada, approximately 3,700 suicides are recorded annually–more deaths than from transport accidents and assaults combined. [Full text]


hospital emergency services, hospital records, injury, Ontario, patient admission, poisoning


Jennifer Bethell (416-864-6099; is with the Suicide Studies Unit at St. Michael's Hospital, Toronto, Ontario, M5B 1W8; Anne E. Rhodes is also with the Suicide Studies Unit, as well as the Institute for Clinical Evaluative Science and the Faculty of Medicine at the University of Toronto, Toronto, Ontario.

What is already known on this subject?

  • Deliberate self-harm (DSH) monitoring is a component of suicide prevention strategies.
  • Emergency department data offer more representative DSH information than do data on inpatient admissions.
  • It is unclear whether emergency department data may still underestimate DSH, specifically, if some emergency department records coded undetermined (UD) represent DSH. Such patterns would have implications for DSH and suicide prevention, research and reporting.

What does this study add?

  • Some emergency department presentations coded UD likely represent DSH, particularly those involving cut/pierce injury or poisoning.
  • Among presentations involving cut/pierce injury or poisoning, the effects of method of injury, acuity and admission to hospital do not fully explain why males younger than age 65 are coded DSH (rather than UD) less often than their female counterparts.
  • Including presentations coded UD as probable DSH increases DSH estimates as much as 60% and attenuates sex differences, the latter most notably in youth.