Cannabis Use Identified as a Novel Risk Factor for Violence in Psychosis With Odds Ratio of 3.34

Criminal history factors had the greatest risk (pooled OR 3.50, 95% CI: 2.37-5.16), followed by substance misuse (OR 2.36, 95% CI: 1.99-2.80). Cannabis use was identified as a novel risk factor in secondary analysis (OR 3.34, 95% CI: 2.32-4.82). Treatment-related factors were protective (OR 0.54, 95% CI: 0.34-0.85). Effects were attenuated in inpatient settings.

Systematic review and meta-analysis searching five databases through June 2022. 47 longitudinal studies, 41 independent samples, 203,297 individuals. Random-effects meta-analysis for risk factors reported in 3+ independent samples. 10-year update of a prior review.

Violence risk assessment in psychosis is critical for clinical management. Cannabis use emerged as a novel and substantial risk factor with an odds ratio comparable to criminal history, suggesting it deserves routine assessment in violence risk evaluation.

The identification of cannabis as a risk factor for violence in psychosis adds clinical urgency to addressing cannabis use in this population. Combined with the protective effect of treatment, it suggests that engaging psychosis patients in treatment and addressing cannabis use could reduce violence risk.

Cannabis finding from secondary analysis needs replication. Most studies from high-income countries. Heterogeneity in violence definitions. Cannot establish causation from observational data.