title: Contagion from peer suicidal behavior in a representative sample of American adolescents.
abstract: BACKGROUND
  Assortative relating is a proposed explanation for the increased occurrence of suicidal behavior among those exposed to suicidal peers. This explanation proposes that high-risk individuals associate with each other, and shared risk factors explain the effect.
  
  
  METHODS
  Data were obtained from the ADDhealth longitudinal survey waves I and II (n=4834 school attending adolescents). People who reported peer suicidal behavior in the first wave were identified and classified as the exposure group. Potentially confounding variables were identified, and propensity scores were calculated for the exposure variable using logistic regression. Inverse-probability-of-treatment weighted regression estimated the effect of exposure on the risk for a suicide attempt during the first two waves.
  
  
  RESULTS
  Weighted analysis showed that the group exposed to a friend's suicide attempt had a higher occurrence of suicide attempts in both waves. Exposure to peer suicide attempts was associated with increased suicide attempts at baseline (RR=1.93; 95%CI= 1.23-3.04) and 1-year follow-up (RR=1.70; 95%CI= 1.12-2.60).
  
  
  CONCLUSIONS
  Only two consecutive years of data are provided. Misclassification and recall bias are possible due to the use of self-report. The outcome may be misclassified due to respondent misunderstanding of what constitutes a suicide attempts, versus non-suicidal self-injury. Non-response and trimming reduced the sample size significantly.
  
  
  CONCLUSIONS
  Assortative relating did not account for all the variance and is currently not sufficient to explain the increased risk after exposure to peer suicidal behavior. Clinicians should assess for exposure to suicidal behaviors in their patients.
authors.affiliation: Department of Community Health Sciences, University of Manitoba, Canada; Manitoba Centre for Health Policy, University of Manitoba, Canada. Electronic address: Jason_Randall@cpe.umanitoba.ca.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Randall
authors.affiliation: Department of Community Health Sciences, University of Manitoba, Canada; Manitoba Centre for Health Policy, University of Manitoba, Canada.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Nickel
authors.affiliation: Department of Epidemiology and Community Medicine, University of Ottawa, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Colman
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D005006:Ethnicity; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D000067074:Peer Influence; D012307:Risk Factors; D012737:Sex Factors; D059020:Suicidal Ideation; D013406:Suicide, Attempted / Q000523:psychology*; D014481:United States
keywords: Adolescent; Attempted suicide; Child; Depression; Propensity score; Prospective; Risk factors; Self-injurious behavior