Association between exposure to suicide and suicidality outcomes in youth.

BACKGROUND: Ecological studies support the hypothesis that suicide may be "contagious" (i.e., exposure to suicide may increase the risk of suicide and related outcomes). However, this association has not been adequately assessed in prospective studies. We sought to determine the association between exposure to suicide and suicidality outcomes in Canadian youth.

METHODS: We used baseline information from the Canadian National Longitudinal Survey of Children and Youth between 1998/99 and 2006/07 with follow-up assessments 2 years later. We included all respondents aged 12-17 years in cycles 3-7 with reported measures of exposure to suicide.

RESULTS: We included 8766 youth aged 12-13 years, 7802 aged 14-15 years and 5496 aged 16-17 years. Exposure to a schoolmate's suicide was associated with ideation at baseline among respondents aged 12-13 years (odds ratio [OR] 5.06, 95% confidence interval [CI] 3.04-8.40), 14-15 years (OR 2.93, 95% CI 2.02-4.24) and 16-17 years (OR 2.23, 95% CI 1.43-3.48). Such exposure was associated with attempts among respondents aged 12-13 years (OR 4.57, 95% CI 2.39-8.71), 14-15 years (OR 3.99, 95% CI 2.46-6.45) and 16-17 years (OR 3.22, 95% CI 1.62-6.41). Personally knowing someone who died by suicide was associated with suicidality outcomes for all age groups. We also assessed 2-year outcomes among respondents aged 12-15 years: a schoolmate's suicide predicted suicide attempts among participants aged 12-13 years (OR 3.07, 95% CI 1.05-8.96) and 14-15 years (OR 2.72, 95% CI 1.47-5.04). Among those who reported a schoolmate's suicide, personally knowing the decedent did not alter the risk of suicidality.

INTERPRETATION: We found that exposure to suicide predicts suicide ideation and attempts. Our results support school-wide interventions over current targeted interventions, particularly over strategies that target interventions toward children closest to the decedent.