Background: 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.
Results: 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%.
Interpretation: Some emergency department presentations coded UD likely represent DSH.