Effectiveness of school-based preventive programs in suicidal thoughts and behaviors: A meta-analysis

•School-based suicide prevention programs could have great reach.•School-based prevention of suicidal thoughts and behavior effective post-assessment.•School-based prevention of suicidal thoughts and behavior may have long-term effects.•Prevention programs aimed at risk factors of suicide are possibly equally effective.•More research on risk factors of suicide should include suicide-related assessments. Suicidal thoughts and behaviors (STBs) among adolescents have hardly decreased despite preventative efforts. School-based prevention programs could have a great reach, yet suicide prevention is not an easy topic to address. To increase acceptability of school-based suicide prevention, it is important to evaluate whether programs that target known risk factors of STBs, such as depression, could be equally effective. We conducted a systematic literature search in major electronic databases. Outcomes were suicidal ideation and behaviors. Multivariate random effects meta-regression-analyses were conducted. Eleven primary studies met the inclusion criteria, totalling 23,230 participants. The post-test effect size was small for both suicidal ideation (g = 0.15) and suicidal behaviors (g = 0.30). Meta-regression indicated that targeting known risk factors of STBs was not a significant modifier of effect size for ideation, indicating equal effectiveness. However, it was significant modifier of effect for behaviors, but only one intervention targeted know risk factors. Effects at follow-up (3–12 months) were also significant but small for both outcomes. Substantial heterogeneity between studies was noted. Only few and small sample size studies could be included that targeted known risk factors of STBs. Therefore, these results should be interpreted with caution. School-based prevention of STBs shows some promise within three months post-test assessments, and potentially also have effects that are sustained over time. More studies are needed to make conclusions regarding school-based interventions that target risk factors of STBs.