The self report questions used to assess lifetime history of self harm at age 16 years were based on those used in the Child and Adolescent Self harm in Europe Study.4 We classified participants as having a history of self harm who responded positively to the item “have you ever hurt yourself on purpose in any way (for example, by taking an overdose of pills or by cutting yourself)?” Two additional questions were used to identify those who had self harmed with suicidal intent; we classified participants as such if they selected “I wanted to die” as a response option to the question “Do any of the following reasons help to explain why you hurt yourself on that (the most recent) occasion?” or they responded positively to the question “On any of the occasions when you have hurt yourself on purpose, have you ever seriously wanted to kill yourself?” We refer to those who self harmed with suicidal intent at some point during their lifetime as having “harmed with suicidal intent” but recognise that many individuals in this group will have also engaged in non-suicidal self harm.22 23 24
