UCSF

INTRODUCTION: Little is known whether cannabis and tobacco use are indicators of suicide-related risks. This longitudinal study examined the associations of cannabis and tobacco use with risks of suicide attempt/death and overdose death over a 2-year follow-up in a cohort of veterans prescribed opioids. METHODS: This study analyzed data in 2024 using a national cohort of 923,291 veterans receiving opioid analgesics in Veterans Health Administration clinics collected during 2014-2019. Cannabis and tobacco use were assessed at cohort entry. Outcomes (suicide attempts, suicide death, overdose death) were obtained at follow-up through 2021. Cause-specific hazard models were used to examine the associations of cannabis and tobacco use with each outcome, adjusting for well-established risk factors for suicide/overdose (e.g., substance use disorders, mental health, sociodemographics). RESULTS: At baseline, 5.4% of the cohort used cannabis, and 39.4% used tobacco. At the end of follow-up (median follow-up time of 6.7-6.8 years), 2.2% of the sample had attempted suicide, 0.4% had died by suicide, and 0.5% had died by overdose. In adjusted models, cannabis use was associated with a higher rate of suicide attempt (hazard ratio=1.11, 95% CI=1.06, 1.15). Current use of tobacco at baseline (versus never use) was associated with a higher rate of suicide attempts (hazard ratio=1.18, 95% CI=1.13, 1.22), suicide deaths (hazard ratio=1.19, 95% CI=1.07, 1.32), and overdose deaths (hazard ratio=1.67, 95% CI=1.51, 1.83). CONCLUSIONS: Cannabis and tobacco use were associated with suicide attempts/deaths and overdose deaths among veterans prescribed opioid analgesics, underscoring a need for monitoring patients who use tobacco and cannabis in this population.