In choosing which drugs to prescribe, doctors often select medications for patients despite a lack of conclusive medical evidence of their effects and safety, according to a new study led by researchers at Dartmouth Medical School and the Stanford University School of Medicine. This practice of "off-label prescribing" offers doctors flexibility and innovation in treating patients but also carries unknown risks.
Of a wide sampling of prescriptions dispensed to patients in 2001, 21 percent were intended to treat medical conditions for which the drugs lacked specific approval from the U.S. Food and Drug Administration (FDA), though other published research suggested possible benefits. About three of every four of those prescriptions were for conditions for which there were little or no evidence of the drugs' effectiveness.
The findings, which will be published May 8 in the Archives of Internal Medicine, are believed to be the first estimate based on a sizeable data base of the actual number of off-label prescriptions among the 100 most-used drugs and 60 other randomly-selected, commonly used medications.
"Our results suggest that prescription drugs are frequently prescribed outside of their evidence base," said David Radley, lead author of the study and a graduate student in the Center for Evaluative Clinical Sciences at Dartmouth Medical School. "The use of unproven therapies could be risky for patients and may represent economically wasteful medication use."
Dr. Randall Stafford, associate professor of medicine at the Stanford Prevention Research Center and senior author of the study, added that many doctors may be unaware if a drug has been FDA-approved for a specific use or how much research supports its use. "Many doctors prescribed drugs when there is little or no evidence supporting its efficacy and safety," Stafford said. "The study can't tell us why doctors prescribe drugs off label. Some uses are more reasonable than others, but, by definition, off-label uses receive less scrutiny than FDA-approved indications."
It is unclear how off-label uses become established within the medical community in cases where limited or no scientific evidence backs up its use. Informal communication between physicians, promising or preliminary scientific studies, and marketing by the pharmaceutical industry could play roles, Stafford said.
Of course, just because a drug is unapproved by the FDA doesn't mean it's ineffective. The FDA approves drugs for treating specific conditions only, and there are many reasons that may explain why a drug has not been approved for treating a particular condition. Since the studies required for FDA approval are often time-consuming and costly, there is little incentive for pharmaceutical companies to seek approval for additional indications, said Radley.
For patients with severe medical conditions, the potential benefits of treatment might outweigh the increased risk associated with off-label use. A physician might choose to prescribe a drug off-label to adjust for a patient's sensitivities, to avoid interactions with other drugs or to try a different approach if FDA-approved drugs haven't worked. While nothing prevents a doctor prescribing a drug off-label, pharmaceutical companies are prohibited from directly promoting such uses.
With collaborator Stan N. Finkelstein, MD, of the Massachusetts Institute of Technology, Radley and Stafford compiled data taken from the 2001National Disease Therapeutic Index, a continuing survey of U.S. physicians conducted by IMS Health, a pharmaceutical and health-care marketing company based in Plymouth Meeting, Pa. The survey compiles data from 3,500 physicians who report information about patient care during two randomly selected, consecutive workdays every quarter. The data represents 403,957 encounters between doctors and patients.
According to the IMS Health data, the 160 commonly prescribed drugs represented an estimated 725 million annual prescriptions. About 575 million, or 79 percent of the total, were prescribed for a condition approved by the FDA. Off-label prescriptions accounted for 150 million, or 21 percent of the total number. Of those, 27 percent were for indications supported by scientific evidence, while the remaining 73 percent, or 109 million prescriptions, had little or no evidence.
The team considered a drug's use scientifically supported if the indication appeared with a listing of at least good evidence in DRUGEX, a nationally recognized pharmaceutical compendium. To be listed in this way, controlled trials or rigorous observations in clinical settings must show evidence of a drug's efficacy.
The medication gabapentin was prescribed off-label most frequently—about 83 percent of the total prescriptions for that drug. In 66 percent of these instances, the drug had little or no scientific evidence for its efficacy in treating the indication. As of 2001, the FDA had approved gabapentin as an anticonvulsant and as a pain-reliever for patients with shingles. Scientific evidence supported its use for social anxiety, migraine prevention and certain diabetic conditions. But doctors commonly prescribed it to treat bipolar disorder and chronic pain, uses not supported by adequate scientific evidence.
"Although this study could not measure the costs associated with off-label medication use, it should remind us that ineffective therapies may not represent the best use of healthcare resources," said Radley. "At a time when healthcare spending is so great, physicians, patients, and policy makers should all be concerned about overuse of unproven therapies."
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