The state of Colorado legalized recreational marijuana in 2013 and began retail sales in 2014. A new study investigated the relationship between recreational marijuana legalization and opioid-related deaths within the state from 2000 to 2015. This study used an interrupted time-series design and included opioid-related deaths in two other states (Nevada, in which medical marijuana is legal, and Utah, in which all cannabis use remains illegal) as covariates. Colorado implemented a prescription drug monitoring program during the study period, which could have affected opioid-related death rates. The authors controlled for this variable in their analysis, although it remained a potential confounder. Counts of opioid-related deaths were collected from CDC WONDER. These deaths and other variables were compared before and after January 1, 2014 using three separate segmented regressions. The authors defined the total effect of recreational marijuana legalization as the percent change at the end of the follow-up period (December 2015). Results indicated there was a statistically significant reduction in trend in opioid-related deaths in Colorado following recreational marijuana legalization laws. When the authors controlled for comparison state trends and Colorado’s prescription drug monitoring program, opioid-related deaths decreased by approximately 0.7 deaths per month, compared to during the baseline period (b = -0.68, CI: -1.34, -0.03). The authors estimate there was a 6.5% reduction in deaths following recreational marijuana legalization. Additional studies in other states with legalized recreational cannabis are needed in order to draw conclusions about the relationship between marijuana legalization and the rate of opioid-related deaths.
Take away: Following recreational marijuana legalization in Colorado in 2014, opioid-related deaths decreased by an estimated 6.5%, relative to before legalization.
Citation: Livingston MD, Barnett TE, Delcher C, et al. (2017). Recreational cannabis legalization and opioid-related deaths in Colorado, 2000–2015 [published online ahead of print October 11 2017], American Journal of Public Health doi: 10.2105/AJPH.2017.304059