New US research shows cannabis laws are associated with a significantly lower rate of opioid prescribing
A cross-sectional study published in the Journal of the American Medical Association (JAMA Internal Medicine) has compared opioid prescribing trends between US states that implemented medical and adult-use cannabis laws from 2011 to 2016.
During this period, an estimated one-third of opioid prescriptions were misused or abused, of which Medicaid shared a disproportionately large burden.
Medicaid fee-for-service and managed care enrollees are reportedly a high-risk population for chronic pain, opioid use disorder, and opioid overdose.
In the US, some states have implemented adult-use cannabis laws that permit all adults aged 21 and over to use the drug.
Most states have also introduced medical cannabis laws, where people with eligible conditions are able to enrol on a patient registry and access a certain amount of cannabis through home cultivation or licensed dispensaries.
State implementation of medical and adult-use cannabis was associated with a lower Medicaid-covered opioid prescribing rate, researchers from the University of Kentucky College of Public Health and Emory University Rollins School of Public Health in the US have found.
Implementation of medical cannabis laws was associated with a 5.88% lower rate of Medicaid-covered prescriptions for all opioids, equivalent to 39.41 fewer opioid prescriptions per 1000 enrollees per year.
Moreover, when states with existing medical cannabis laws implemented adult-use cannabis laws, this was associated with an additional 6.38% lower opioid prescription rate.
Adult-use cannabis laws led to 39.67 fewer opioid prescriptions per 1000 enrollees per year.
Results from sensitivity analyses were consistent with the main findings.
“Overprescribing of opioids is considered a major driving force behind the opioid epidemic in the United States,” say the authors Dr Hefei Wen and Dr Jason Hockenberry.
“Marijuana is one of the potential non-opioid alternatives that can relieve pain at a relatively lower risk of addiction and virtually no risk of overdose.”
They argue that their results show liberalisation of cannabis laws to reduce use and consequences of prescription opioids deserves consideration during policy discussions.
“This study provides some of the first empirical evidence that the implementation of medical and adult-use marijuana laws from 2011 to 2016 was associated with lower Medicaid-covered opioid prescribing rates and spending,” they say.
“Most opioid use disorder and overdose cases occurred in patients with legitimate prescription from healthcare professionals for pain management.
“Marijuana liberalisation, therefore, may have benefited these patients by providing them with legal protection and access to marijuana as an alternative relief from their pain conditions.”
The authors point out that as with any observational study, they cannot definitely establish causality between cannabis liberalisation and opioid prescribing.
And while they concede cannabis liberalisation alone cannot solve the opioid epidemic, it is “but one potential aspect of a comprehensive package to tackle the epidemic”.
A second study also published in JAMA Internal Medicine this month, by researchers from the University of Georgia, US, found that patients filled fewer daily doses of any opioid in states with a medical cannabis law.
Hydrocodone use decreased by 2.320 million daily doses (or 17.4%) filled by medical cannabis dispensaries, while morphine use decreased by 0.361 million daily doses (or 20.7%).
“Medical cannabis laws are associated with significant reductions in opioid prescribing in the Medicare Part D population,” the authors concluded.
“This finding was particularly strong in states that permit dispensaries, and for reductions in hydrocodone and morphine prescriptions.”
Cannabidiol, in preparations for therapeutic use containing 2% or less of other cannabinoids found in cannabis, is now legal for medical use in Australia for some conditions, which vary by state.
Outside of this, cannabis is considered a Schedule 9 drug or “prohibited substance”.
However it has been decriminalised for personal use/minor offences in the Northern Territory, South Australia, the Australian Capital Territory, and Victoria – meaning those caught with it are either fined or directed to an education program rather than charged with a criminal offence.