Association of Substance Use with Suicide Mortality

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, I2: 99 %) was significantly associated with risk for suicide. Alcohol (SMR: 65.39, 95 % CI: 3.02-19.62, I2: 99 %), tobacco (SMR: 1.83, 95 % CI: 1.20-2.79, I2: 83 %), opioid (SMR: 5.46, 95 % CI: 3.66-8.15, I2: 96 %), cannabis (SMR 3.31, 95 % CI: 1.42-7.70, I2: 95 %), and amphetamine (SMR 11.97, 95 % CI: 3.13-45.74, I2: 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, I2: 98 %) than males (SMR: 5.21, 95 % CI: 3.09-8.78, I2: 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.