Changes in Opioid and Benzodiazepine Poisoning Deaths After Cannabis Legalization in the US: A County-level Analysis, 2002–2020

Abstract

Background: Cannabis legalization for medical and recreational purposes has been suggested as an effective strategy to reduce opioid and benzodiazepine use and deaths. We examined the county-level association between medical and recreational cannabis laws and poisoning deaths involving opioids and benzodiazepines in the US from 2002 to 2020. Methods: Our ecologic county-level, spatiotemporal study comprised 49 states. Exposures were state-level implementation of medical and recreational cannabis laws and state-level initiation of cannabis dispensary sales. Our main outcomes were poisoning deaths involving any opioid, any benzodiazepine, and opioids with benzodiazepines. Secondary analyses included overdoses involving natural and semi-synthetic opioids, synthetic opioids, and heroin. Results: Implementation of medical cannabis laws was associated with increased deaths involving opioids (rate ratio [RR] = 1.14; 95% credible interval [CrI] = 1.11, 1.18), benzodiazepines (RR = 1.19; 95% CrI = 1.12, 1.26), and opioids+benzodiazepines (RR = 1.22; 95% CrI = 1.15, 1.30). Medical cannabis legalizations allowing dispensaries was associated with fewer deaths involving opioids (RR = 0.88; 95% CrI = 0.85, 0.91) but not benzodiazepine deaths; results for recreational cannabis implementation and opioid deaths were similar (RR = 0.81; 95% CrI = 0.75, 0.88). Recreational cannabis laws allowing dispensary sales was associated with consistent reductions in opioid- (RR = 0.83; 95% CrI = 0.76, 0.91), benzodiazepine- (RR = 0.79; 95% CrI = 0.68, 0.92), and opioid+benzodiazepine-related poisonings (RR = 0.83; 95% CrI = 0.70, 0.98). Conclusions: Implementation of medical cannabis laws was associated with higher rates of opioid- and benzodiazepine-related deaths, whereas laws permitting broader cannabis access, including implementation of recreational cannabis laws and medical and recreational dispensaries, were associated with lower rates. The estimated effects of the expanded availability of cannabis seem dependent on the type of law implemented and its provisions.

Recreational and Medical Cannabis Legalization and Opioid Prescriptions and Mortality

“…However, there was an increase in overdose deaths involving prescription opioids between years 2 and 4 after medical cannabis law implementation, suggesting potential co-use of cannabis and opioids that was not always under clinical supervision. Meanwhile, our finding indicating a possible association between recreational cannabis laws and reduced synthetic opioid deaths may suggest that users of fentanyl (and other synthetic opioids) switched to recreational cannabis or reduced use of other sedating substances, such as benzodiazepines, that can increase overdose risk when mixed with fentanyl . It is also possible that recreational cannabis laws make cannabis more available and thus reduce initiation of opioid use.…”

“…These results contrast with recent studies that suggested that recreational and medical cannabis legalization are associated with reductions in opioid prescriptions 21 , 22 and medical cannabis legalization is associated with an increase in opioid mortality. 14 , 15 , 16 , 17 These conflicting findings may arise from many factors, including differences in the study cohorts and periods examined, methods of defining the exposures and outcomes of interest, and empirical approaches used to evaluate these laws.…”

“…Some evidence suggests that medical cannabis legalization has been associated with reductions in opioid prescribing, [9][10][11] and in some cases, opioidrelated mortality, 12 whereas other evidence suggests that medical cannabis legalization was not associated with changes in opioid prescriptions 13 or has been associated with increased, rather than decreased, opioid-related mortality. [14][15][16][17] Studies examining the effect of recreational cannabis laws have found reductions in opioid prescriptions associated with recreational cannabis legalization, [18][19][20][21][22] and evidence on the effects of recreational cannabis laws is mixed, with studies indicating either no association with or an increase in opioid mortality. [14][15][16] Apart from finding mixed results on opioid overdose deaths, the current literature has several limitations.…”

United States Marijuana Legalization and Opioid Mortality Trends Before and During the First Year of the COVID-19 Pandemic

“…44 A report in 2018 concluded that medical marijuana legalization was associated with a 30% reduction in Schedule III opioid Medicaid prescriptions. 45 Two county-level studies in states that allowed marijuana dispensaries to operate had lower opioid-mortality rates in counties with medical and recreational dispensaries, 46,47 albeit the county-level methodology utilized has been negatively critiqued. 7,48…”

“…44 A report in 2018 concluded that medical marijuana legalization was associated with a 30% reduction in Schedule III opioid Medicaid prescriptions. 45 Two county-level studies in states that allowed marijuana dispensaries to operate had lower opioid-mortality rates in counties with medical and recreational dispensaries, 46,47 albeit the county-level methodology utilized has been negatively critiqued. 7,48 At the national level, an update of aforementioned studies by other investigators indicates that legal medical marijuana is associated with higher opioid mortality, particularly when available through retail dispensaries, and that recreational marijuana may be correlated with greater death rates relative to the counterfactual of no legal cannabis.…”