A new US study suggests that opioid-related mortality rates fall in counties where there are legal cannabis stores.
Cannabis was first legalised for medical use in the US in 1996; recreational legalisation began in 2012 with a number of states following suit. Previous research on the effect of legal access to cannabis on opioid overdose mortality had produced conflicting results, with a 2014 study showing a slow increase in deaths, but a subsequent study showing that it reversed over time.
Data on opioid mortality for adults 21 and over was drawn from 2014-2018 CDC data, and a website called Weedmaps for cannabis dispensary details in the 23 states plus the District of Columbia where cannabis dispensaries were allowed to operate as of 2017.
The number of cannabis dispensaries in a county was negatively related to log-transformed age-adjusted opioid mortality rate (β -0.17, 95% CI -0.23 to -0.11). An increase in the number of storefront dispensaries from one to two was linked to a 17% reduction in death rates of all opioid types, and an increase from two to three stores was associated with a further 8.5% drop in mortality.
Eight states plus the District of Columbia allowed recreational storefronts and 15 allowed only medical dispensaries. An increase in medical dispensaries from one to two resulted in a 15% drop in mortality rate; an increase in recreational dispensaries from one to two led to an 11% drop.
Co-author Balázs Kovács, PhD, of Yale University School of Management, said: “We find this relationship holds for both medical dispensaries, which serve only patients who have a state-approved medical card or doctor’s recommendation, as well as for recreational dispensaries, which sell to adults 21 years and older.”
An accompanying editorial pointed out that the relationship was not clear, noting that were was no evidence of substitution. Additionally, individual experiences of benefits and harms could not be inferred.
Although findings are suggestive of a possible link between the increased prevalence of cannabis dispensaries and reduced opioid-related mortality, they do not show causality, Kovács emphasised. “While we find a particularly strong association between the prevalence of storefront dispensaries and fentanyl-related opioid deaths, it is not clear whether cannabis use and fentanyl mortality rates are more specifically linked, or if the strength of the association is due to the rise in fentanyl use and mortality rates during the study period,” he said.
He added that the potential harms of cannabis, including cognitive development of adolescents, schizophrenia and other medical conditions, and public safety risks, should not be ignored.
Source:MedPage TodayJournal information: Hsu G and Kovács B “Association between county level cannabis dispensary counts and opioid related mortality rates in the United States: panel data study” BMJ 2021; DOI: 10.1136/bmj.m4957.
