Background: Two-thirds of people with suicidal thoughts never attempt suicide, suggesting that suicidal ideation (SI) and suicide attempts (SA) may be governed by distinct mechanisms. While ideation-to-action frameworks suggest interventions may differentially affect these outcomes, it remains unclear whether psychotherapies associated with reduced SI severity are also linked to reduced SA incidence. 

Methods: To address the low base rate of SA and sparse SI measurement in randomized controlled trials (RCTs), we will conduct a meta-analysis using the existing Metapsy suicide prevention database, based on searches in PubMed, Embase, PsycInfo, Web of Science, Scopus, and CENTRAL from inception to April 1, 2025. Studies will include participants of any age with any mental health problem from any setting. Among these, trials reporting both post-treatment SI severity and SA incidence will be eligible. Using a data-driven exploratory approach, we will first identify trials showing a significant effect on SI severity, then meta-analyze pooled effects on SA incidence within this subset using three-level models. Outcomes will be post-treatment SI severity (Hedges’g) and SA incidence (relative-risk). 

Expected Results: Trials showing significant reductions in SI severity may show a corresponding pooled reduction in SA incidence, suggesting that psychotherapy effects on SI and SA reflect a continuum. 

Discussion: Findings may clarify whether these outcomes are dissociable in treatment research.