A reexamination of medical marijuana policies in relation to suicide risk

• Prior research suggested that medical marijuana policies lead to reduced suicide risk.
• We attempted to update, replicate and extend this research.
• We found no association between medical marijuana policies and suicide risk.
• The difference is likely explained by additional covariates in the newer analyses.
• It is unlikely that medical marijuana policies reduce suicide risk.

ObjectivesPrevious research has suggested that medical marijuana policies lead to reductions in suicide rates. In this study, we further investigate the association between these policies and within-state changes in suicide risk.MethodsData on suicide deaths (n = 662,993) from the National Vital Statistics System Multiple Cause of Death files were combined with living population data. Fixed-effects regression methods were employed to control for state differences in suicide rates and national and state secular trends. Analyses extended prior research that suggested a protective effect of medical marijuana policies by incorporating newer data and additional covariates.ResultsAfter adjustment for race/ethnicity, tobacco control policies, and other covariates, we found no association between medical marijuana policy and suicide risk in the population ages 15 and older (OR = 1.000; 95% CI: 0.956, 1.045; p = 0.98), among men overall (OR = 0.996; 95% CI: 0.951, 1.043; p = 0.87) or for any other age-by-sex groups.ConclusionWe find no statistically significant association between medical marijuana policy and suicide risk. These results contradict prior analyses which did not control for race/ethnicity and certain state characteristics such as tobacco control policies. Failure to control for these factors in future analyses would likely bias estimates of the associations between medical marijuana policy and health outcomes.