Access to legal cannabis stores is associated with a reduction in opioid related deaths in the United States, particularly those linked to synthetic opioids such as fentanyl, finds a joint University of California and Yale University study published by the British Medical Journal. The findings may have implications for tackling opioid misuse.
The authors are Professor Greta Hsu of the Graduate School of Management at the University of California – Davis, and Associate Professor Balazs Kovacs of the School of Management at Yale University. The following material was published by the BMJ:
Opioids are ‘morphine-type’ drugs that relieve short-term (acute) pain and pain at the end of life. There is little evidence that they are helpful for long-term (chronic) pain, but they are often prescribed for this reason.
This has led to widespread misuse and a sharp rise in overdose deaths, particularly in the United States. In 2018, there were more than 46,000 fentanyl related deaths, representing over two thirds of all US opioid related deaths that year.
Some studies have suggested that increased access to cannabis stores – legally authorised to sell medical and recreational cannabis – may help to reduce opioid related deaths, but the evidence so far is mixed.
To explore this further, researchers examined relationships between medical and recreational cannabis stores (referred to as dispensaries) and opioid related deaths from 2014 to 2018.
Their findings are based on data for 812 counties within the 23 US states that allowed legal cannabis dispensaries to operate by the end of 2017. Information on state level cannabis legislation was combined with county level data on licensed dispensaries and opioid related mortality rates.
After controlling for population characteristics and other potentially influential factors, the researchers found that counties with a higher number of active cannabis dispensaries were associated with reduced opioid related mortality rates.
According to this estimate, an increase from one to two dispensaries in a county was associated with an estimated 17% reduction in all opioid related mortality rates.
This association held for both medical and recreational dispensaries and appeared particularly strong for deaths associated with synthetic opioids other than methadone, with an estimated 21% reduction in mortality rates associated with an increase from one to two dispensaries.
An increase from two to three dispensaries was associated with a further 8.5% reduction in all opioid related mortality rates.
This study is the first to examine the association between active cannabis dispensary operations and opioid related mortality rates at the more fine grained county level.
However, the results are observational, so can’t establish cause, and the researchers stress that while cannabis is generally thought to be less addictive than opioids, it still carries potential harms and public safety risks should not be ignored.
But they say their findings suggest “a potential association between increased prevalence of medical and recreational cannabis dispensaries and reduced opioid related mortality rates.”
And they call for “a greater understanding of the impact of cannabis legalisation on opioid misuse and public health outcomes before policy-makers can weigh the potential benefits against the harms of promoting cannabis legalisation.”
In a related editorial (see link to the editorial below), researchers argue that cannabis liberalisation “cannot be regarded as a remedy to the opioid crisis until a robust evidence base is available”.
Although some may interpret these findings as evidence supporting cannabis liberalization to address the opioid crisis, they point out that “such conclusions are currently premature without evidence of causality”.
Further experimental studies including individual level data of those with use of prescription opioids and illicit opioids “would inform a more nuanced understanding of the substitution between opioids and cannabis”, they conclude.
Study details
Association between county level cannabis dispensary counts and opioid related mortality rates in the United States: panel data study
Professor Greta Hsu and Associate Professor Balazs Kovacs
Author affiliations: Graduate School of Management at the University of California – Davis – and the School of Management at Yale University, United States.
Published by the British Medical Journal on 27 January 2021
Abstract
Objective
To examine county level associations between the prevalence of medical and recreational cannabis stores (referred to as dispensaries) and opioid related mortality rates.
Design Panel regression methods.
Setting
812 counties in the United States in the 23 states that allowed legal forms of cannabis dispensaries to operate by the end of 2017.
Participants
The study used US mortality data from the Centers for Disease Control and Prevention combined with US census data and data from Weedmaps.com on storefront dispensary operations. Data were analyzed at the county level by using panel regression methods.
Main outcome measure
The main outcome measures were the log transformed, age adjusted mortality rates associated with all opioid types combined, and with subcategories of prescription opioids, heroin, and synthetic opioids other than methadone. The associations of medical dispensary and recreational dispensary counts with age adjusted mortality rates were also analyzed.
Results
County level dispensary count (natural logarithm) is negatively related to the log transformed, age adjusted mortality rate associated with all opioid types (β=−0.17, 95% confidence interval −0.23 to −0.11).
According to this estimate, an increase from one to two storefront dispensaries in a county is associated with an estimated 17% reduction in all opioid related mortality rates.
Dispensary count has a particularly strong negative association with deaths caused by synthetic opioids other than methadone (β=−0.21, 95% confidence interval −0.27 to −0.14), with an estimated 21% reduction in mortality rates associated with an increase from one to two dispensaries.
Similar associations were found for medical versus recreational storefront dispensary counts on synthetic (non-methadone) opioid related mortality rates.
Conclusions
Higher medical and recreational storefront dispensary counts are associated with reduced opioid related death rates, particularly deaths associated with synthetic opioids such as fentanyl.
While the associations documented cannot be assumed to be causal, they suggest a potential association between increased prevalence of medical and recreational cannabis dispensaries and reduced opioid related mortality rates.
This study highlights the importance of considering the complex supply side of related drug markets and how this shapes opioid use and misuse.
[link url="https://www.bmj.com/company/newsroom/legal-cannabis-stores-linked-to-fewer-opioid-deaths-in-the-united-states/"]BMJ news material – Legal cannabis stores linked to fewer opioid deaths in the United States (Open access)[/link]
[link url="https://www.bmj.com/content/372/bmj.n163.full"]British Medical Journal – Editorial – Too early to tell whether cannabis liberalisation reduces opioid deaths (Restricted access)[/link]
[link url="https://www.bmj.com/content/372/bmj.m4957"]British Medical Journal article – Association between county level cannabis dispensary counts and opioid related mortality rates in the United States: panel data study (Open access)[/link]
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