LOS ANGELES — Do pharmaceutical companies and their marketing budgets have undue influence over what drugs doctors prescribe? A new study shows that despite the billions spent by pharmaceutical companies on outreach to physicians, most doctors retain some level of diversity in their prescribing choices.
The study, led by researchers with the Schaeffer Center for Health Policy and Economics at USC, examined the 10 most widely used classes of therapeutic drugs in the United States from 2005 to 2007, and is the first to look at whether prescription diversity has an effect on patient-level outcomes.
In the current issue of the American Journal of Managed Care, the study shows that most doctors have habitual favorites when it comes to prescriptions: a single drug, whether brand name or generic, accounts for 40 to 70 percent of most doctors’ new prescriptions in a category. But with the remaining prescriptions, doctors branched out and tried new therapies, on average prescribing two additional drugs in 8 of the 10 categories studied.
Doctors treating patients with a range of coexisting medical conditions and with multiple health insurers tended to have broader prescribing habits, according to the study, suggesting that doctors sought to match medication to their patient’s specific conditions and payment plans when deviating from their favorite drug. About 15 percent — fewer than 1 in 6 — physicians prescribed only brand-name drugs.
“These results were even more striking considering the small number of initial prescriptions per physician and the dominance of brand drugs in many of the categories studied,” said lead author Geoffrey Joyce, director of health policy at the Schaeffer Center at USC and associate professor of clinical pharmacy and pharmaceutical economics and policy at the USC School of Pharmacy.
Doctors prescribed most broadly with antidepressants: selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs). In this category, 45 percent of doctors prescribed 5 or more different drugs to new patients over the study period. Fewer than 1 percent prescribed a single drug in the category.
In five of the categories studied, brand drugs had more than 50 percent of market share. In two categories, generic drugs were overwhelmingly preferred. Nearly 90 percent of physicians prescribing opiates prescribed only generic drugs. In contrast, among doctors prescribing only one statin — drugs used to lower cholesterol levels — more than 80 percent of doctors prescribed the market leader and most heavily marketed drug.
But prescribing broadly may have moderate or little effect on certain measures of patient outcomes, according to the study. The researchers found little evidence that broader prescribing significantly affected adherence to a drug treatment over a six month period or average out-of-pocket cost per 30-day prescription.
Dana Goldman, Norman Topping Chair in Medicine and Public Policy at USC and director of the Schaeffer Center at USC; Neeraj Sood, associate professor at the USC School of Pharmacy; and Mariana Carrera of Case Western University were also authors on the paper.
The research was funded by the National Institute on Aging.
About the Schaeffer Center for Health Policy and Economics at USC
The Leonard D. Schaeffer Center for Health Policy and Economics at the University of Southern California is one of the nation’s premier policy research centers. Its mission is promote health and value in healthcare delivery through innovative research and policy, both in the United States and internationally. More than 20 distinguished scholars and faculty work in the Schaeffer Center at USC to investigate a wide array of topics, including: promoting value in health care spending, understanding how public policy affects medical innovation, improving insurance design, encouraging cost-effective care and identifying the broader macroeconomic consequences of health care trends. The Schaeffer Center’s work is supplemented by a visiting scholars program and collaborations with other universities, so that outside researchers can take advantage of the Schaeffer Center’s research infrastructure and data.
Contact: Suzanne Wu at (213) 740-0252