States with Medical Cannabis Dispensaries Had Bigger Drop in Opioid Prescriptions Interview with

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David Bradford, Ph.D.
Busbee Chair in Public Policy
Department of Public Administration and Policy
University of Georgia
Athens, GA 30602 What is the background for this study?

Response: To give you some background, in 2016, part of our research team (Bradford and Bradford) published the first study to directly examine the impact that medical cannabis laws (MCLs) may be having on prescription use. We used yearly physician-level Medicare Part D data, looked at nearly all prescription drugs used to treat 9 broad categories of illness/diagnoses, and found substantial reductions in prescriptions. We published a follow-up study in 2017, this time using data from Medicaid Fee-for-Service.

Again, we found significant substitution away from prescription medications. In both of these studies, pain was included in the list of conditions for which cannabis may be used in patients, and in both studies, pain prescriptions fell. One of the unanswered questions from both of those studies, though, was what *type* of pain medications were being reduced.  From a public health standpoint, when we’re worried about opioid overdose, it matters whether the substitution away from pain medications is coming from substitutions away from things like NSAIDs or whether there is substitution away from opioids. What are the main findings? 

Response: Our main findings were that patients filled fewer doses of opioid medications in states that have  medical cannabis laws in place. The results varied by type of opioid as well as by type of MCL. Overall, states with dispensary-based medical cannabis laws saw 3.7 million fewer daily doses filled, whereas states with home cultivation-based MCLs only MCLs saw 1.8 million fewer daily doses filed. The type of access (dispensary versus home cultivation only) had a measurable effect on the decrease in prescriptions that we found. Dispensary-based . medical cannabis laws were associated with 17.4% fewer hydrocodone daily doses and 20.7% fewer morphine daily doses filled, whereas home cultivation-based medical cannabis laws were associated with 9.4% fewer hydrocodone daily doses filled. What should readers take away from your report?

Response: There are two main takeaways from this work.

The first is that patients and physicians seem to be responding to the introduction of medical cannabis as if it were medicine — in many ways as they would with the introduction of a new FDA-approved medical treatment.

A second takeaway is that the type of medical cannabis law seems to matter quite a bit. As we discussed above, states that had active dispensaries in place saw a greater reduction in daily doses filled compared to states that only allowed home cultivation. Policy makers should consider this before designing an MCL, particularly if mitigating the effects of the opioid crisis is one of the primary motivations for adopting the policy. What recommendations do you have for future research as a result of this work?

Response: We recommend that future studies examine the associations between .medical cannabis laws and opioid-related mortality, in a more detailed way than has been done in the past.  We also think that researchers should secure the funding necessary to study the effect of MCL and medical cannabis access on privately-insured populations (not just Medicare and Medicaid).

Finally, it would be useful to delve further into how the variations in the medical cannabis laws themselves (for example home cultivation versus dispensary, whether or not caregivers are allowed to distribute cannabis, the legal limit of medical cannabis possession, which conditions are protected, and how the law was adopted etc.) can alter the effectiveness of the MCL in other health service use. We have already shown that the way that medical cannabis can be accessed matters a great deal when it comes to reducing opioid utilization. It is likely that  medical cannabis law policy variation affects a number of important societal outcomes as well. 


Bradford AC, Bradford WD, Abraham A, Bagwell Adams G. Association Between US State Medical Cannabis Laws and Opioid Prescribing in the Medicare Part D Population. JAMA Intern Med. Published online April 02, 2018. doi:10.1001/jamainternmed.2018.0266

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Last Updated on April 2, 2018 by Marie Benz MD FAAD