Opioid-overdose deaths increased in states across the country between 1999 and 2010, but states that legalized medical marijuana saw less-steep increases than those without, according to a study published in JAMA Internal Medicine this week.
Growing use of prescription opioids over the past 2 decades to treat chronic pain has helped drive increasing rates of opioid overdoses. To help reduce the problem, state and federal governments have instituted prescription monitoring programs and drug safety plans and tightened restrictions on prescribing popular opioids. Some of these efforts have yielded reductions in opioid overdoses on a state level, but national rates continue to rise.
At the same time, a growing number of states have legalized medical marijuana. In states like Colorado, where medical marijuana has been legal since 2000, the primary reason for a physician to recommend medical marijuana is pain. Some of the other indications for prescribing medical marijuana include nausea from cancer chemotherapy and poor appetite and accompanying weight loss resulting from a chronic illness such as HIV infection.
Marcus A. Bachhuber, MD, a Robert Wood Johnson Foundation Clinical Scholar at the Philadelphia Veterans Affairs Medical Center, and his colleagues analyzed opioid overdose rates in states with or without legalized medical marijuana to see whether its availability to treat pain helps reduce opioid deaths. They found that while opioid overdose deaths have continued to increase in all states, states that permit prescribing medical marijuana had lower rates of opioid overdose deaths compared with those that do not.
Bachhuber discussed his results with news@JAMA.
news@JAMA: Why did you decide to do the study?
Dr Bachhuber: I’m a primary care physician and I’ve talked to many patients with chronic pain. In the past, I’ve had patients who said they’ve tried prescription opioid painkillers but the only thing that worked to reduce their pain was marijuana. So, my colleagues and I wondered whether people might be choosing to treat their pain with marijuana in states where this is legal, and if these states might see lower rates of painkiller overdoses or deaths.
news@JAMA: You found that the rates of opioid overdose were lower in states allowing medical marijuana. Can you explain what that means?
Dr Bachhuber: We found that rates of opioid overdose deaths have increased in all states. But in the years after the legalization of medical marijuana, states that did so had a rate that was 25% lower than what we’d expect to see in that state, given past trends and what was going on in the rest of the country.
news@JAMA: Why might making medical cannabis available reduce opioid overdose rates?
Dr Bachhuber: Going into the study, we hypothesized that patients with chronic pain might replace opioids with medical marijuana or supplement opioid medications with medical marijuana, allowing them to reduce their opioid dose. Alternatively, there is still a debate about whether medical marijuana might lead patients to use other drugs, so rates of opioid overdose might have increased. We thought there could be a change in either direction, and that’s why we decided to study it.
news@JAMA: Your study can’t prove that medical marijuana was the factor that reduced opioid overdoses. Might there be other explanations?
Dr Bachhuber: One of the limitations of our study is that we can’t identify, measure, and control for every factor that was different between the states and might be contributing to our results. If broader changes were happening in states that also implemented medical marijuana laws, such as changes in patterns of pain treatment or illicit drug use, those could be influencing our results and have nothing to do with medical marijuana. But, if medical marijuana laws are in fact reducing opioid overdose deaths, we would need studies following individuals over time to see how exactly these laws are shifting behavior.
news@JAMA: How much do we know about the use of opioids or marijuana for pain treatment?
Dr Bachhuber: Opioids are approved by the FDA for the treatment of pain; they have undergone randomized trials, but there is very little evidence for long-term use for more than a few months. Marijuana is still considered a Schedule I drug, meaning the FDA says there is no valid medical use. Because of this, there is not much research out there to help us understand the risks and benefits of medical marijuana, including what conditions could be successfully treated, which patients might benefit the most, and what the risks may be. Also, head-to-head studies of marijuana and opioids would be incredibly useful for clinical practice.
news@JAMA: What is the main take-home message from your study?
Dr Bachhuber: Our study provides evidence of a possible unexpected public health benefit of medical marijuana legalization. Medical marijuana may have other possible impacts on public health, and as more states enact these laws, it will be worth continuing to look at this issue.