Opioid payments to doctors decline following medical cannabis legalisation, finds study

Direct payments from opioid producers to pain doctors in the US saw a significant decline following the legalisation of medical cannabis, a new study has found.

A new paper from researchers at the University of Florida, University of Southern California and Purdue University, highlights the impact of medical cannabis legalisation on direct payments from opioid manufacturers to physicians.

They identified a ‘significant decrease’ in direct payments from opioid manufacturers to pain medicine physicians ‘as an effect of [medical marijuana law] passage,’ concluding that doctors based in states with legal access to medical cannabis are ‘prescribing fewer opioids’.

This is another indication that medicinal cannabis may have the potential to be a useful tool in tackling opioid misuse, which is responsible for around 70% of drug overdose deaths worldwide every year. 

The relationship between opioid manufacturers and doctors 

In 2021, the global opioid industry was estimated to be worth $13.9 billion.

Pharmaceutical companies behind the production of opioid-based medications have been known to form relationships with doctors as a tool to market their products. 

As the paper points out, “opioid manufacturers use different forms of interactions to engage with physicians on a regular basis,” and “one of the most common conduits to facilitate such interactions is through direct payments to physicians from opioid manufacturers.”

In recent years it has come to light that some physicians have received significant sums of money from opioid manufacturers, which according to the researchers may come in the form of speaking and consultancy fees, conference travel reimbursements or meal vouchers. 

A 2018 study from Harvard T.H. Chan School of Public Health, Harvard Medical School (HMS), and CNN, found that, in 2014 and 2015, opioid manufacturers paid hundreds of doctors sums in the six figures, while thousands more were paid over $25,000.

Meanwhile, according to the CDC, overdose deaths involving opioids, including prescription opioids, heroin, and synthetic opioids (like fentanyl), have increased by more than eight times since 1999, leading to some states introducing new regulations to limit the prescribing of opioids.

What effect does medical cannabis legalisation have?

A number of studies have indicated that medical cannabis may be a safe and effective alternative to opioids for pain management, with research suggesting that opioid use has reduced in states where medical cannabis is legal.

The scientists behind this new study went one step further, to examine what happened to these prescribing payments following the legalisation of medical cannabis. Under the Physician Payments Sunshine Act, which came into force in 2010, pharmaceutical manufacturers are required to report any payments made to doctors.

They analysed transaction data involving direct payments from opioid manufacturers to physicians from 2014 to 2017 and developed a ‘novel penalized synthetic control model’ to draw causal conclusions. 

Their primary analysis considered pain medicine physicians from 13 states, of which three had passed a law to legalise medical cannabis in the second quarter of 2016. 

As well as identifying a ‘significant decrease’ in financial interactions between opioid manufacturers and physicians as an effect of medical cannabis legalisation, they provide evidence that this decrease is ‘due to the availability of medical marijuana as a substitute’.

In addition this effect was higher among female physicians and in areas with ‘higher white, less affluent, and more working-age populations’.

The authors point out that this decline could be due to a number of factors including states introducing new policies designed to curb the prescribing of opioids, and recommend further studies in this area.

“Our study finds a significant decrease in financial interactions between opioid manufacturers and physicians as an effect of MML [medical marijuana law] passage,” they state.

“The finding that the opioid manufacturers in states that passed MML are stepping away from this particular form of interaction is concerning, for such activity can significantly affect the opioids ecosystem… If physicians are not actively engaged with opioid manufacturers in getting updates and driving research, eventually, patients are deprived of optimal care.”

They add: “As we currently do not have a comprehensive understanding of the effects of medical marijuana on individuals and society at large, intensive research on opioids and their safe consumption are needed for optimal pain management in the immediate future.”

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