CONTACT Marijuana-opiate study raises questions - Dr. Christian Thurstone

An article recently published in the Journal of the American Medical Association claims states with medical marijuana laws are associated with significantly lower rates of opioid mortality.

There are significant limitations to this research making it irresponsible to interpret from it a drop in opiate use or death because of medical marijuana laws. The limitations of this research are so striking that a re-examination of the data is in order. The original investigation is co-authored by Marcus Bachhuber, M.D.; Brendan Saloner, Ph.D.; Chinazo O. Cunningham, M.D., M.S.; and Colleen L. Barry, Ph.D., M.P.P.

Because I see in so many marijuana studies similar (and similarly severe) limitations and other sweeping conclusions the data examined often do not support, I have respectfully asked the National Institute on Drug Abuse to offer guidance to researchers — and to medical journal editors and to journalists working for mainstream news organizations. Already, I’m seeing headlines proclaiming medical marijuana is shown to cause fewer prescription-drug deaths. To call such news coverage a grave disservice is a gross understatement.

Colorado-based medical researcher Stacy Solomonsen-Sautel, Ph.D., with whom I have co-authored marijuana research at the University of Colorado Denver (marijuana diversion to kids, more diversion of marijuana, marijuana leading to more fatal accidents) and drug policy expert Kevin Sabet, Ph.D., director of the University of Florida’s Drug Policy Institute and co-founder of marijuana-policy reform group Smart Approaches to Marijuana, wasted no time taking a detailed look at the data and methodologies used in the JAMA-published study. I invite you to review their full explanation of this study’s limitations. I summarize them for you here:

As the study authors conceded, the raw data showed that medical marijuana states had higher rates of opiate deaths. When the authors introduced four possible reasons for this, the rate completely flipped. This is a major red flag, signifying that possibly one of those four reasons alone may have influenced the death rate, and could be a sign of what researchers call a “spurious relationship” between MMLs and death rates.

The study lumped together states with small and restricted marijuana distribution with states that have open, widespread distribution and commercialization, possibly biasing the results.

The study did not take into account the true implementation of medical marijuana laws. It simply looked at when laws were passed and a handful of years before and after those laws were passed. Marijuana researchers — and the editors of medical journals — must take great care to note when a law’s implementation happens. For example, if a state approves medical marijuana on Jan. 14, that doesn’t mean it’s permitting the sale of the substance the following day.

Though the study did control for some other possible explanations for the lower opiate death rate in medical marijuana states, it left out some of the most critical possible alternative explanations. The study failed to examine the influence of expanded methadone and buprenorphine programs in states, or the possible influence of major law enforcement interventions (e.g. pill mill shut downs and major operations by DEA in states like Florida), or even Naltrexone utilization. The study also did not take into account prevention campaigns or strategies.

The study authors found that heroin overdose – even if no other opiate was used – was also lower in medical marijuana states. Heroin use is not typically used for pain management – offering more evidence that the authors stated connection between lower opiate deaths and MMLs might represent a spurious relationship.

If medical marijuana laws are reducing opiate deaths, shouldn’t we also see reduced prescription drug emergency room mentions and treatment admissions in those medical marijuana states? The authors fail to examine these possibilities.

I concur with the summary statement written by Drs. Sabet and Solomonsen-Sautel:

“Much more research must be done before making the sweeping conclusion that medical marijuana laws reduce opiate overdose deaths. Though that connection may be intrinsically appealing – some could view the idea that people might use a milder drug versus an opiate as an improvement – too many uncertainties lie in this JAMA analysis.”

Other instances of research from which people have drawn conclusions the data do not support:

About Chris Thurstone

Dr. Christian Thurstone is one of only a few dozen physicians in the United States who are board-certified in general, child and adolescent and addictions psychiatry. He is Director of Behavioral Health Services at Denver Health and a professor of psychiatry at the University of Colorado, where he conducts research on youth substance use and addiction and serves as director of medical training for the university’s addiction psychiatry fellowship program. You can read more about him here.

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