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CNN leaves out key limitation of study on legalizing marijuana and opioid use


3 Star


Marijuana legalization could help offset opioid epidemic, studies find

Our Review Summary

Health professionals—from doctors to policy experts—are exploring strategies for controlling the opioid crisis gripping the U.S. Advocates for legalizing marijuana for medical or recreational purposes have suggested that increased access to marijuana could curb opioid use. The two studies published in JAMA Internal Medicine discussed in this CNN article found that state legalization of medical marijuana was associated with a decrease in opioid prescriptions.

But before it presented the data, the article led readers to believe the study findings “suggest that there is merit” in “using medical marijuana to help Americans struggling with opioid addiction,”—which is beyond what the studies could possibly show.

The article took another misstep when it stated that the researchers analyzed opioid prescriptions to “evaluate whether medical marijuana could function as an effective and safe alternative to opioids.” The data the researchers looked at could not answer that question. These were not clinical trials comparing pain relief from marijuana with pain relief from opioids in patients who would typically be prescribed opioids. They were analyses of data on opioid prescriptions in Medicaid and Medicare databases.

The researchers detail the limitations of their studies, as does a commentary published along with them. But only one limitation made it into the article: the caveat that the results may not be generalizable to the entire U.S. population because they only used data on patients enrolled in Medicare and Medicare Part D.

The biggest limitation goes unmentioned: There was no way to know if anyone was actually choosing to use marijuana instead of opioids.


Why This Matters

The article addressed two hot button topics: opioid addiction and the legalization of marijuana. Ninety people in the U.S. die each day from an opioid overdose, and families and friends of individuals struggling with opioid addiction are searching for ways to help their loved ones. It’s easy to find anecdotal stories online from people who say marijuana helped curb their withdrawal symptoms, but whether marijuana helps people overcome opioid addiction or can be used instead of opioids to ease pain cannot be answered in studies such as these.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

The article did not mention how much it costs to use marijuana to treat pain or whether medical marijuana is covered by private health insurance, Medicare or Medicaid.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


The article quantified the findings this way:

The researchers found that states that allow the use of cannabis for medical purposes had 2.21 million fewer daily doses of opioids prescribed per year under Medicare Part D, compared with those states without medical cannabis laws. Opioid prescriptions under Medicaid also dropped by 5.88% in states with medical cannabis laws compared with states without such laws, according to the studies.

It could have also mentioned that the study that looked at Medicaid data did not see reductions in opioid prescriptions in all states with medical marijuana laws.

Below, in evidence quality, we address a related concern: Does the story do enough to clarify that these findings aren’t proof that marijuana legalization reduces opioid use?

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

The article didn’t explain that marijuana can be addictive and has side effects. These include an increased heart rate, which can increase the risk of a heart attack, especially in older people with heart problems. In some people, long-term use can cause intense nausea and vomiting. In addition, high doses of marijuana can cause psychosis, delusions or hallucinations. When smoked, marijuana can cause breathing problems and increase a person’s risk of developing a lung infection.

Does the story seem to grasp the quality of the evidence?

Not Satisfactory

The story did not discuss important limitations to the evidence. Chiefly, that the research wasn’t designed to prove that easing access to marijuana causes a drop in opioid abuse (or prescriptions). It only detected a pattern. And as the associated JAMA editorial points out, this pattern may not actually have anything to do with easier marijuana access:

… there are a multitude of other factors that may affect the association between medical cannabis and opioids in a given state and that are known to be associated with regional variation in opioid prescribing that were not adjusted for such as racial composition, educational attainment, prevalence of disease, disability, and suicide rates.

Does the story commit disease-mongering?


It is widely acknowledged that the country is in the midst of an opioid epidemic. In 2016, there were more than 63,600 drug overdose deaths in the United States.

Does the story use independent sources and identify conflicts of interest?

Not Satisfactory

The story quoted the lead authors of each of the studies. It also quoted the independent co-author of the invited commentary. Another source was Melissa Moore, New York deputy state director for the Drug Policy Alliance. The article did not mention that the Drug Policy Alliance advocates for legalizing and regulating marijuana. There is one brief paragraph in the article that described “some skeptics” who “argue that medical marijuana could actually worsen the opioid epidemic” but no one is quoted.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

The article did not mention any other policies being studied for reducing opioid prescriptions, overdoses or deaths.

Does the story establish the availability of the treatment/test/product/procedure?


The article included information about the number of states that have legalized certain types of marijuana use.

Does the story establish the true novelty of the approach?


The story explained that marijuana has been shown to be effective in treating chronic pain, and noted that more research is needed on its medical benefits.

Does the story appear to rely solely or largely on a news release?


The story did not appear to be based on a news release.

Total Score: 5 of 10 Satisfactory


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