Abstract
BACKGROUND: Rates of suicide mortality and substance use have increased globally. We updated and extended existing systematic reviews of the association between substance use and suicide. METHODS: This systematic review and meta-analysis explored the association between substance use and suicide mortality in peer reviewed, longitudinal cohort studies published from 2003 through 2024. Risk of bias was assessed using the Newcastle-Ottawa Scale. Pooled data were analyzed using a quality effects model. Meta-regression was used to assess the effect of moderation by study quality. Asymmetry in funnel plots and Doi plots were used to detect reporting bias. FINDINGS: The analysis involved 47 studies from 12 countries. Substance misuse (SMR: 5.58, 95 % CI: 3.63-8.57, I(2): 99 %) was significantly associated with risk for suicide. Alcohol (SMR: 65.39, 95 % CI: 3.02-19.62, I(2): 99 %), tobacco (SMR: 1.83, 95 % CI: 1.20-2.79, I(2): 83 %), opioid (SMR: 5.46, 95 % CI: 3.66-8.15, I(2): 96 %), cannabis (SMR 3.31, 95 % CI: 1.42-7.70, I(2): 95 %), and amphetamine (SMR 11.97, 95 % CI: 3.13-45.74, I(2): 99 %) misuse were each linked to higher rates of suicide mortality. The association between substance misuse and suicide was stronger for females (SMR: 12.37, 95 % CI: 7.07-21.63, I(2): 98 %) than males (SMR: 5.21, 95 % CI: 3.09-8.78, I(2): 99 %) overall and in analyses of specific substances. Further disaggregated data were not available to sufficiently explore for potential health inequities across social factors. CONCLUSIONS: This meta-analysis highlights that substance misuse remains a significant suicide risk factor. It underscores the need for universal and targeted prevention and equitable access to effective interventions.