Slowly but surely, the stigma surrounding marijuana use is losing its grip in the U.S. Since the 1990s, advocates have pushed for a re-evaluation of cannabis (the plant species name often used interchangeably with marijuana) as a viable treatment for a host of ailments. As of 2018, 33 states and the District of Columbia have approved the medical use of cannabis, while 10 states have legalized marijuana for recreational use. Despite this fact, at the federal level, marijuana remains a Schedule 1 drug under the Controlled Substances Act, defined as a drug with no currently accepted medical use and a high potential for abuse.

New research from the University of Michigan, published in the February issue of Health Affairs, takes a deeper dive into state medical marijuana registry data to provide more insight into its use.

 "We did this study because we wanted to understand the reasons why people are using cannabis medically, and whether those reasons for use are evidence based," says lead author Kevin Boehnke, Ph.D., research investigator in the department of anesthesiology and the Chronic Pain and Fatigue Research Center.

He and his U-M colleagues Daniel J. Clauw, M.D., a professor of anesthesiology, medicine, and psychiatry and Rebecca L. Haffajee, Ph.D., assistant professor of health management and policy, as well as U-M alum Saurav Gangopadhyay, M.P.H., a consultant at Deloitte, sought out data from states with legalized medical use of marijuana. 

To examine patterns of use, the researchers grouped patient-reported qualifying conditions (i.e. the illnesses/medical conditions that allowed a patient to obtain a license) into evidence categories pulled from a recent National Academies of Sciences, Engineering and Medicine report on cannabis and cannabinoids. The report, published in 2017, is a comprehensive review of 10,000 scientific abstracts on the health effects of medical and recreational cannabis use. According to the report, there was conclusive or substantial evidence that chronic pain, nausea and vomiting due to chemotherapy, and multiple sclerosis (MS) spasticity symptoms were improved as a result of cannabis treatment.

Evidence-based relief

One major finding of the Health Affairs paper was the variability of available data. Less than half of the states had data on patient-reported qualifying conditions and only 20 reported data on the number of registered patients. The authors also noted that the number of licensed medical users, with 641,176 registered medical cannabis patients in 2016 and 813,917 in 2017, was likely far lower than the actual number of users.

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However, with the available data, they found that the number of medical cannabis patients rose dramatically over time and that the vast majority — 85.5 percent — of medical cannabis license holders indicated that they were seeking treatment for an evidence-based condition, with chronic pain accounting for 62.2 percent of all patient-reported qualifying conditions. 

"This finding is consistent with the prevalence of chronic pain, which affects an estimated 100 million Americans," the authors state.

This research provides support for legitimate evidence-based use of cannabis that is at direct odds with its current drug schedule status, notes Boehnke. This is especially important as more people look for safer pain management alternatives in light of the current opioid epidemic.

Notes Boehnke, "Since the majority of states in the U.S. have legalized medical cannabis, we should consider how best to adequately regulate cannabis and safely incorporate cannabis into medical practice."

CBD and Chronic Pain

In a separate, recently published letter in the Annals of Internal Medicine, Boehnke and Clauw attempt to address the fact that there is minimal guidance available for physicians seeking to counsel patients about the use of cannabis.

They note that tetrahydrocannabinol (THC) causes most of the risks associated with cannabis, including intoxication, impairment and addiction. Cannabidiol (CBD) is non-intoxicating and evidence suggests anti-inflammatory and pain-relieving effects from its use.

"CBD is incredibly accessible, as it is available online from a variety of vendors. However, the quality control for safety (for example, whether there are residual solvents, pesticides, etc.) and potency is widely variable," says Boehnke.

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The researchers stress that CBD is not yet ready to be considered as a first-line treatment for chronic pain.

"That may change as more clinical trials are conducted, but at this point in time we don't understand which cannabinoids and administration routes are best for which types of pain," Boehnke notes.

However, as more and more patients turn to cannabis for pain relief, Clauw and Boehnke recommend that physicians and scientists "do our part by listening, showing compassion, and using the best available knowledge to support patients and keep them safe on their journey."