Plenty of attention has been paid to the link between payments from pharmaceutical companies and the drugs a doctor prescribes, including opioids.
But a new study shows something as simple as a meal may be making the difference in just how many opioids are getting prescribed.
Published this week in JAMA Internal Medicine, researchers said they found physicians who received lunches from drug companies prescribed 9% more opioids than doctors who didn't.
The increase took place even as the overall rate of opioid prescriptions was falling, he said.
"It is a lot when you think about how large this sample was, how many physicians there are across the United States and how widespread this practice is," said Scott Hadland, M.D., the study's lead author from the Grayken Center for Addiction at Boston Medical Center.
Researchers analyzed prescribing information from Medicare Part D, which represents about 43% of the active physician workforce to identify. They compared that to information from the Open Payments Database to see payments from pharmaceutical companies to physicians in 2014.
In all, about 7%, or about 25,000 doctors, received opioid-related payments.
The vast majority of the marketing payments (92%) were made in the form of meals at an average cost of about $13. But they added up to about $9 million worth of total payments, Hadlund said.
That's a lot of interactions, Hadlund said.
"Why do physicians accept meals? Because they are readily available and it's a small reward that physicians can get in their practice and physicians, just like any other professional, appreciate small rewards," Hadland said.
He doesn't believe doctors are acting nefariously. "I think if we could talk to the vast majority of physicians, most would not believe the meal they went out on influenced their prescribing behavior. I think the effect here is very subtle. But it's widespread. That has a large public health effect."
The center's findings echo previous studies which have found smaller payments from drug companies could have a larger impact on prescribing habits than large ones.
Hadland said he plans to focus next on convincing lawmakers about the importance of these small gifts. In particular, he said, New Jersey is working on a rule change that would cap the total dollar value of gifts from drug companies to doctors at $10,000 a year.