Longitudinal association between self-injurious thoughts and behaviors and suicidal behavior in adolescents and young adults: A systematic review with meta-analysis

Background: Adolescents with previous self-injurious thoughts and behaviors (SITB) have over 2-fold risk of dying by suicide, higher than older ages. This meta-analysis aims to disentangle the association of each SITB with subsequent suicidal behavior in adolescence/young adulthood, the contribution of each SITB, and the proportion of suicide deaths with no previous suicide attempt. Methods: We searched 6 databases until June 2015. Inclusion criteria: 1. Assessment of any previous SITB [a) suicidal thoughts and behaviors (ideation; threat/gesture; plan; attempt); b) non-suicidal thoughts and behaviors (thoughts; threat/gesture; self-injury); c) self-harm] as a risk factor of suicide attempt or suicide death; 2. Case control or cohort studies; 3. Subjects aged 12-26y. Random effect models, metaregression analyses including mental health and environmental variables, and population attributable risks (PAR)s were estimated. Results: From 23,682 potentially eligible articles, 29 were included in the meta-analysis (1,122,054 individuals). While 68% of all youth suicide deaths had no previous suicide attempt, suicide death was very strongly associated with any previous SITB (OR=22.53, 95%CI: 18.40-27.58). Suicide attempts were also associated with a history of previous SITB (OR=3.48, 95%CI: 2.71-4.43). There were no moderating effects for mental health and environmental features. The PAR of previous SITB to suicide attempts is 26%. Limitations: There is considerable heterogeneity between the available studies. Due to limitations in the original studies, an over-estimation of the proportion dying at their first attempt cannot be ruled out, since they might have missed unrecognized previous suicide attempts. Conclusions: Although more than two thirds of suicide deaths in adolescence/young adulthood have occurred with no previous suicidal behavior, previous SITBs have a much higher risk of dying by suicide than previously reported in this age group.