Overprescribing of opioids is not limited to a few bad apples

This finding contrasts with previous studies by others that indicated the U.S. opioid epidemic is stoked by a small population of prolific prescribers operating out of corrupt "pill mills."

The study, which examined Medicare prescription drug claims data for 2013, will appear in a research letter that will be published online Dec. 14 in JAMA Internal Medicine.

"The bulk of opioid prescriptions are distributed by the large population of general practitioners," said lead author Jonathan Chen, MD, PhD, an instructor of medicine and Stanford Health Policy VA Medical Informatics Fellow.

The researchers found that the top 10 percent of opioid prescribers account for 57 percent of opioid prescriptions. This prescribing pattern is comparable to that found in the Medicare data for prescribers of all drugs: The top 10 percent of all drug prescribers account for 63 percent of all drug prescriptions.

The specialties that prescribed the most Schedule II opioids in 2013 were family practice (15.3 million prescriptions), internal medicine (12.8 million), nurse practitioner (4.1 ) and physician assistant (3.1 million prescriptions), according to the study. Schedule II drugs are substances approved by the Food and Drug Administration for medical use and recognized as carrying a high potential of abuse.

"These findings indicate law enforcement efforts to shut down pill-mill prescribers are insufficient to address the widespread overprescribing of opioids," Chen said. "Efforts to curtail national opioid overprescribing must address a broad swath of prescribers to be effective."

He added, "Being a physician myself, I am acutely aware of the emotional angst that can occur when deciding whether to prescribe opioids to a patient who may have simultaneously developed a chronic-pain and substance-dependence problem. The public health epidemic of opioid overuse is perhaps not surprising given the tenfold increase in volume over the past 20 years."

Different findings from different data set

In 2011, a study by the California Workers' Compensation Institute found that 1 percent of prescribers accounted for one-third of opioid prescriptions, and that the top 10 percent accounted for 80 percent of prescriptions. The new Stanford study used a different data set: Instead of California workers' compensation prescriptions, it looked at prescriber data from the 2013 Medicare prescription drug coverage claims and investigated whether such disproportionate prescribing of opioids occurs in the national Medicare population.

Both studies looked at Schedule II opioids, which include the commonly abused drugs hydrocodone, codeine and fentanyl.

The data set created by the Centers for Medicare and Medicaid Services included all prescribers and represented all Medicare prescription drug coverage claims for 2013: 808,020 prescribers and 1.18 billion claims. The researchers focused on the data for Schedule II opioids: 381,575 prescribers and 56.5 million claims.

"This data set indicates no special distinctions in the concentration of opioid prescribing among Medicare prescribers," said Chen. "The earlier study suggests potentially aberrant behavior among those extreme outlier prescribers, while implying the remaining majority do not contribute much to the problem -- and now we know this is not the case."

The authors attribute the difference in the California Workers' Compensation data to the traits of that specific population, which perhaps has a greater prevalence of multiple illnesses or employment in jobs more prone to injury, while the Medicare population is more generally representative of the population at large.

They found that opioid prescriptions per prescriber were concentrated among specialty services for interventional pain management (1,124.9 prescriptions, on average, per prescriber), pain management (921.1), anesthesiology (484.2) and physical medicine and rehabilitation (348.2). By sheer volume, however, there are so many more general practitioners that they dominated the total quantity of prescriptions.

Anna Lembke, MD, is the study's senior author. Other Stanford co-authors are Keith Humphreys, PhD, professor of psychiatry and behavioral sciences, and associate professor of medicine Nigam Shah, MBBS, PhD.

The research was supported in part by the U.S. Department of Veterans Affairs Office of Academic Affiliations, the VA Health Services Research and Development Service, the National Institute of General Medical Sciences (grant R01 GM101430) and the Peter F. McManus Charitable Trust.

Stanford's Department of Medicine also supported the work.