Study: Doctors stick with one drug per category

Doctors tend to have favorite drugs in each medication class, although they are willing to adjust based on a patient’s health plan, according to the results of a study.

The research, led by investigators with the Schaeffer Center for Health Policy and Economics at the University of Southern California, examined the 10 most widely used classes of therapeutic drugs in the United States from 2005 to 2007. It is the first study to examine whether prescription diversity has an effect on patient-level outcomes, according to a statement from the university.

Published in the American Journal of Managed Care, the study shows that most doctors have favorite prescriptions. A single drug, whether brand name or generic, accounts for 40% to 70% of most physicians’ new prescriptions in a category, according to the study. With the remaining prescriptions, doctors tried new therapies, on average prescribing two additional drugs in eight of the 10 categories studied.

Physicians tended to have broader prescribing habits when treating patients with a range of coexisting medical conditions and with multiple health insurers, according to the study. This finding suggests that prescribers seek to match a medication to a patient’s specific condition and payment plan when deviating from their favorite drug, according to authors.

Doctors prescribed most broadly with antidepressants, specifically, selective serotonin reuptake inhibitors and serotonin and norepinephrine reuptake inhibitors. In this category, almost half of doctors prescribed five or more different drugs to new patients over the study period. Fewer than 1% prescribed a single drug in the category.

Brand-name drugs had more than half of market share in five of the categories studied. In two categories, generic drugs were overwhelmingly preferred. Nearly 90% of physicians prescribing opiates prescribed only generic drugs. In contrast, among doctors prescribing only one statin, more than 80% prescribed the market leader and most heavily marketed drug.

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 6-month period or average out-of-pocket cost per 30-day prescription.

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