Systematic review of the impact of interventions changing access to lethal means on suicide attempts and deaths

Objective: The study objective was to examine if interventions changing access to lethal means are associated with changes in suicide deaths and/or attempts by conducting a systematic review of controlled intervention studies. Methods: Authors searched key databases (PubMed, PsycInfo, CINAHL) from inception to March 2024 for longitudinal controlled intervention studies with at least one contemporaneous comparator group evaluating the impact of interventions changing access to lethal means on suicide attempts and/or deaths in a primarily adult population. Reviewers dually screened articles, then extracted study characteristics and assessed methodological quality. Results: Researchers screened 8522 studies and 36 articles met eligibility for inclusion. Most studies evaluated the impact of population-level firearm interventions on suicide deaths and found that stricter regulations were associated with a small reduction, if any, in total and/or firearm-specific suicide deaths. The ecological level of analysis precluded individual-level causal inference. Findings within interventions targeting methods other than firearms were limited, mixed and/or inconclusive. Notably, no high-quality randomised controlled trials (RCTs) were identified that met our eligibility criteria. Conclusion: Future studies should use an RCT design or advanced statistical causal inference techniques to further elucidate the effectiveness of these interventions on suicide deaths and/or attempts.