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.