Peer victimisation during adolescence and its impact on XXXX in early adulthood: prospective cohort study in the United Kingdom.

@entity1 @entity308
OBJECTIVE: To investigate the strength of the association between victimisation by peers at age 13 years and @entity308 at 18 years. DESIGN: Longitudinal observational study. SETTING: Avon Longitudinal Study of Parents and @entity1 , a UK community based birth cohort. @entity1 : 6719 @entity1 who reported on peer victimisation at age 13 years. MAIN OUTCOME MEASURES: Depression defined according to international classification of diseases, 10th revision (ICD-10) criteria, assessed using the clinical interview schedule-revised during clinic assessments with @entity1 when they were aged 18 years. 3898 @entity1 had data on both victimisation by peers at age 13 years and @entity308 at age 18 years. RESULTS: Of the 683 @entity1 who reported frequent victimisation at age 13 years, 101 (14.8%) were @entity308 according to ICD-10 criteria at 18 years; of the 1446 @entity1 reporting some victimisation at age 13 years, 103 (7.1%) were @entity308 at age 18 years; and of the 1769 @entity1 reporting no victimisation at age 13 years, 98 (5.5%) were @entity308 at age 18 years. Compared with @entity1 who were not victimised those who were frequently victimised by peers had over a twofold increase in odds of @entity308 (odds ratio 2.96, 95% confidence interval 2.21 to 3.97, P<0.001). This association was slightly reduced when adjusting for confounders (2.32, 1.49 to 3.63, P<0.001). The population attributable fraction suggested that 29.2% (95% confidence interval 10.9% to 43.7%) of @entity308 at age 18 years could be explained by peer victimisation if this were a causal relation. CONCLUSION: When using observational data it is impossible to be certain that associations are causal. However, our results are consistent with the hypothesis that victimisation by peers in adolescence is associated with an increase in the risk of developing @entity308 as an adult.
