Bullying by peers is a major problem; approximately 25% of children in the United Kingdom report exposure to such victimisation.1 Bullying victimisation is associated with a myriad of emotional and behavioural problems throughout adolescence.2 Over the past few years, the media have focused public attention on instances of suicide and self harm among adolescents who have been bullied, and a commensurate rise in anti-bullying policies and laws has occurred on both sides of the Atlantic.3 4 Surprisingly, very few studies have tested the assumption that exposure to bullying in childhood increases the likelihood that a child or adolescent will self harm. Existing studies are often limited by cross sectional designs, the possibility that unmeasured background risk factors can lead children both to be victimised and to self harm (selection effects), and reliance on the same person to report both exposure to bullying and self harm behaviour, which may create spurious associations (reporter bias).5 6 7 8 Moreover, a need exists for research into self harm as early as possible in adolescence, to inform prevention of injuries.
