How medical marijuana is reducing opioid prescriptions

By Kevin Manne

BUFFALO, N.Y. — In states where medical marijuana is legal, payments from opioid manufacturers to physicians have decreased significantly — suggesting that marijuana may be emerging as a viable alternative to opioids for pain management, according to new research from the University at Buffalo School of Management.

Available online ahead of publication in the Journal of the American Statistical Association, the study examined the impact of medical marijuana legalization on the financial incentives that opioid manufacturers provide to physicians. These payments often include consulting fees, conference travel and other incentives — practices that pharmaceutical companies have faced criticism for using to influence medical decisions.

“The availability of new pain management options can change the financial dynamics between drug companies and health care providers,” says study co-author Wreetabrata Kar, PhD, assistant professor of marketing in the UB School of Management. “Our findings indicate that medical marijuana is increasingly viewed as a substitute for opioids in chronic pain treatment, with the potential to transform pain management practices and help mitigate the opioid crisis that has profoundly affected communities across the U.S.”

The researchers analyzed quarterly data from 2014-17 on direct payments from opioid manufacturers to physicians using their new penalized synthetic control method, a robust tool for estimating causal effects with observational data. This information included both pre- and post-legalization of medical marijuana in states across the U.S. mandated by the Sunshine Act, which requires such payments to be reported to ensure transparency. 

They found that direct payments from opioid manufacturers to physicians significantly decreased after states passed medical marijuana laws. The decline was particularly notable for pain medicine specialists, suggesting that physicians may be shifting away from prescribing opioids in favor of recommending medical marijuana where it is legal.

The effects of medical marijuana legalization are also influenced by community demographics. Payments from opioid manufacturers to doctors decreased in lower-income areas, areas with higher Black populations, and areas where the median age of the population was between 30 and 40 years.

“Lower income regions tend to have higher rates of chronic pain and opioid misuse, making them key areas for potential substitution with medical marijuana,” says Kar. “Black patients are also less likely to be prescribed opioids for pain, and younger populations may be more open to alternative treatments, which could explain the different impacts of marijuana legalization in these communities.”

Kar collaborated on the study with Bikram Karmakar, PhD, assistant professor of statistics at the University of Florida, and Gourab Mukherjee, PhD, associate professor of data sciences and operations at the University of Southern California Marshall School of Business.