Physicians in the United States who completed their initial training at a higher-ranked medical school write significantly fewer opioid prescriptions annually than those from lower-ranked schools, even if those physicians practice in the same specialty and county, suggests the new research, published Monday in the National Bureau of Economic Research's working paper series
In other words, physician education may play a role in America's opioid epidemic
, which suggests it could be a potential tool in combating that crisis as well.
Yet the paper comes with several limitations and has not been peer-reviewed.
"It's plausible that the messages students get in medical school affect their behavior," said Keith Humphreys, a professor of psychiatry and behavioral sciences at Stanford University who was not involved in the new paper.
"So, I think there is a real effect here, but I think the study probably overstates how big it is," he said.
The paper, authored by Janet Currie, a professor of economics at Princeton University, and Molly Schnell, a Ph.D. candidate in economics at the university, included data on the number of opioid prescriptions filled annually between 2006 and 2014 at US retail pharmacies. The data, which came from the public pharmaceutical market intelligence company QuintilesIMS
, also included information on each physician prescriber for the opioids.
The researchers analyzed the data for how many opioid prescriptions the prescriber wrote each year as well as where that prescriber completed medical school. The researchers also examined how each medical school ranked on the latest US News and World Report "Best Medical Schools: Research Rankings
The researchers found that general practitioners who trained at the highest-ranked school, Harvard, wrote an average of 180.2 opioid prescriptions per year, while physicians from the lowest-ranked schools wrote an average of nearly 550 per year.
"We see that a higher medical school rank is associated with fewer opioid prescriptions: on average, physicians from the lowest ranked US medical schools write three times as many opioid prescriptions as physicians trained at Harvard Medical School, the top ranked school," the researchers wrote in the paper.
"This striking inverse relationship between the number of annual opioid prescriptions and medical school rank reflects two factors: physicians from higher ranked medical schools are less likely to write any opioid prescriptions; and conditional on writing any opioid prescription, physicians from higher ranked medical schools write fewer opioid prescriptions on average," they wrote.
The researchers also noted that "physicians trained in most regions outside of the US write significantly fewer opioid prescriptions per year on average than physicians trained domestically. The stark differences between physicians trained in various regions of the world suggest that differences in training are likely to be important."
However, even though the researchers controlled for the counties in which the physicians practiced and their specialties, they didn't measure other factors that could have skewed their data, Humphreys said.
"They don't have data on how many patients doctors saw, just how much they prescribed. ... So a part of this could also show that physicians from lower-ranked medical schools see more patients, and so they prescribe more," Humphreys said.
Additionally, "they're comparing doctors in the same counties, but there is a lot of variation in a county," he said. "There's community clinics, Medicaid clinics, VA hospitals, private practices ... and that means there's a lot of variation in patients, even within the same specialty."
Yet Currie, one of the paper's authors, said there was no database that would allow the researchers to know how many patients each physician in the United States sees. The researchers excluded all ZIP codes with teaching hospitals, she said, since it is more common for doctors from top medical schools to move into research and teaching positions, which may help eliminate doctors who see very few patients.
Still, they "find a strong relationship between rank and prescribing," Currie said.
The United States is in the midst of an opioid overdose epidemic, according to the US Department of Health and Human Services
According to the Centers for Disease Control and Prevention, 91 Americans die every day from an opioid overdose
. In 2015, a total of 33,091 Americans lost their lives to opioids, half of them from legal prescription painkillers such as oxycodone or hydrocodone.
Last month, US Food and Drug Administration Commissioner Scott Gottlieb announced the agency's plans to expand its requirements for prescription opioid manufacturers to provide prescriber training to clinicians,
including pharmacists and physicians.
"One of the most important things for people to be aware of about the epidemic is that much of the problem is doctor prescriptions. The emphasis in public discussions is often on treatment, and on illegal opioids which are also important. But a big part of the epidemic is being driven by doctors prescribing medications for short term and chronic pain, and people becoming addicted because of these prescriptions," Currie wrote in an email.
"Moreover, there is a lot of controversy now about whether opioids are even effective for chronic pain outside of palliative care, given that people build up tolerance to them. It seems that some patients who start with one problem, chronic pain, end up with two problems, chronic pain and addiction. It is important for doctors to know about this and to modify their prescribing behavior," she said.
The researchers wrote that including training aimed at reducing opioid prescription rates in the medical school curricula could be a beneficial approach in addressing the country's opioid epidemic.
Humphreys seemed to agree.
"One of the things a good medical school will do for doctors is insulate them from the solicitations they will be exposed to their entire career from the pharmaceutical industry," including companies that market opioid drugs, he said. "One of the most valuable things we can contribute is some skepticism and the sensibility to find out if something is going to help their patients by looking in the journals and not in the marketing."