Legalized
medical cannabis lowers opioid use, study finds
University of Georgia, School of Public and International
Affairs
States that have approved medical cannabis laws saw a dramatic
reduction in opioid use, according to a new study by researchers at the
University of Georgia.
In a paper published today in the Journal of the
American Medical Association, Internal Medicine, researchers examined the
number of all opioid prescriptions filled between 2010 and 2015 under Medicare
Part D, the prescription drug benefit plan available to Medicare enrollees.
In states with medical cannabis dispensaries, the researchers
observed a 14.4 percent reduction in use of prescription opioids and nearly a 7
percent reduction in opiate prescriptions filled in states with
home-cultivation-only medical cannabis laws.
"Some of the states we analyzed had medical cannabis laws throughout the five-year study period, some never had medical cannabis, and some enacted medical cannabis laws during those five years," said W. David Bradford, study co-author and Busbee Chair in Public Policy in the UGA School of Public and International Affairs. "So, what we were able to do is ask what happens to physician behavior in terms of their opiate prescribing if and when medical cannabis becomes available."
Since California approved the first medical cannabis law in
1996, 29 states and the District of Colombia have approved some form of medical
cannabis law.
"Physicians cannot prescribe cannabis; it is still a
Schedule I drug," Bradford said. "We're not observing that
prescriptions for cannabis go up and prescriptions for opioids go down. We're
just observing what changes when medical cannabis laws are enacted, and we see
big reductions in opiate use."
The researchers examined all common prescriptions opiates,
including hydrocodone, oxycodone, morphine, methadone and fentanyl. Because
heroin is not a legal drug, it was not included as part of the study.
Last year, the U.S. Department of Health and Human Services
declared a public health emergency related to the abuse of opiates. Opioid
overdoses accounted for more than 42,000 deaths in 2016, more than any previous
year on record, and more than 40 percent of opioid overdose deaths involved a
prescription opioid, according to HHS.
Opioid prescription rates increased from about 148 million
prescriptions in 2005 to 206 million prescriptions by 2011, Bradford said. This
coincided with an increase in the number of opioid-related deaths.
"There is a growing body of literature that suggests
cannabis may be used to manage pain in some patients, and this could be a major
component of the reductions we see in the use of opiates," he said.
The researchers did not, however, see any significant reductions
in the number of non-opioid drugs prescribed during the study period.
"In other studies, we examined prescription rates for
non-opioid drugs such as blood thinners, flu medications and phosphorus
stimulants, and we saw no change," said Ashley Bradford, lead author of
the study and graduate student in UGA's department of public administration and
policy. "Medical cannabis wouldn't be an effective treatment for flu or
for anemia, so we feel pretty confident that the changes we see in opioids are
because of cannabis because there is a legitimate medical use."
The researches concede that if medical cannabis is to become an
effective treatment, there is still much work to be done. Scientists are only
just beginning to understand the effects of the compounds contained in
cannabis, and an effective "dose" of cannabis would need to be
defined clearly so that each patient receives a consistent dose.
"Regardless, our findings suggest quite clearly that
medical cannabis could be one useful tool in the policy arsenal that can be
used to diminish the harm of prescription opioids, and that's worthy of serious
consideration," David Bradford said.
Coauthors on the paper Amanda Abraham, assistant professor of
public administration and policy at UGA and Grace Bagwell Adams, assistant
professor of health policy and management in UGA's College of Public Health.
