Contrary to previous research and popular assumptions, legalization of, and broader access to, medical cannabis has not reduced opioid overdose death rates.
A study at Stanford University in California showed no protective effect of medical cannabis. In fact, states that legalized medical cannabis actually experienced a 22.7% increase in opioid overdose deaths.
“There has been an idea touted by people and the cannabis industry and everyone invested in finding solutions to the opioid crisis that passing cannabis laws is one way to do that,” lead author Chelsea L. Shover, PhD, epidemiologist and postdoctoral fellow in psychiatry, Stanford University School of Medicine, Palo Alto, California, told Medscape Medical News.
“The big point and takeaway from our study is that medical cannabis laws don’t seem to reduce opioid overdoses at the population level, but that does not mean we shouldn’t keep researching and having policy discussions about laws related to cannabis,” she said.
The findings were published online June 10 in Proceedings of the National Academy of Sciences.
A previous study published in JAMA Internal Medicine in 2014 showed that, from 1999 to 2010, states with medical cannabis laws experienced slower increases in opioid overdose deaths. The current study analyzed the period from 1999 to 2017.
The earlier study “created a sensation by showing that state medical cannabis laws were associated with lower-than-expected opioid overdose mortality rates from 1999 to 2010,” the authors write.
The enthusiasm for this approach occurred “despite the caveats of the [original study] authors and others to exercise caution when using ecological correlations to draw causal, individual-level conclusions,” the investigators note.
Between the conclusion of the previous study and the end date of the current study (2010 – 2017), 32 states enacted medical cannabis laws, including 17 that allowed only medical cannabis with low levels of tetrahydrocannabinol (THC, the psychoactive compound in cannabis), and 8 states enacted recreational cannabis laws.
Nevertheless, opioid overdose deaths actually increased dramatically during that period.
The researchers wanted to revisit the question using the same methods used in the original study but extending the time period by 7 years.
In addition, they created a model that accounted for the presence of recreational cannabis law, which presumably points to greater access to cannabis, or a low-THC restriction, which accounts for more limited access.
Therefore, if broader access to cannabis rather than medical cannabis specifically is associated with lower opioid overdose mortality, “we would expect to see the most negative association in states with recreational laws and the least negative association (or even positive) association in states with low-THC-only laws,” the authors note.
Compounding the Problem?
The authors reanalyzed the 1999 – 2010 period and obtained estimates similar to those of the original study.
However, they also found slight differences that were probably attributable to missing values for 30 state/year combinations — for instance, the investigators from the earlier study estimated a 24.8% reduction in deaths per 100,000 population associated with the introduction of a medical cannabis law, while the investigators of the current study estimated a “statistically indistinguishable” 21.1% decrease.
Also replicating the findings of the original model, Shover and colleagues found that none of the four time-varying covariates including annual state unemployment rate and presence of prescription drug monitoring p
Source link : Medscape.com
Publish date : 2019-06-11T22:39:46Z
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