Samples effect residents’ drug prescribing habits

Study: Patients might end up spending more

An analysis of the prescribing practices of 29 internal medicine residents in an inner-city Minneapolis clinic indicates that residents with access to sample pharmaceuticals were more likely to prescribe heavily advertised drugs and less likely to prescribe over-the-counter (OTC) drugs than their peers.

The study, reported in the August issue of the American Journal of Medicine, was conducted by researchers at the University of Minnesota and Abbott Northwestern Hospital, who recorded the prescribing habits of the residents over a six-month period.

Researchers looked at prescriptions written for highly advertised drugs compared to drugs commonly used for the same indication that were less expensive, available over the counter, or available in generic formulation. By random selection, half of the residents agreed not to use available free drug samples stocked in the clinic by pharmaceutical representatives.

After selecting drug classes where samples of heavily advertised drugs were provided to the clinic, and where lower priced alternative formulations existed, the authors looked for prescribing differences between physicians who had access to free samples and those who agreed before the study to not use the samples.

Author Richard F. Adair, MD, wrote that in addition to tendencies toward prescribing heavily advertised drugs, resident physicians with access to drug samples also showed a trend toward less use of inexpensive drugs.

While the initial samples of the drug were free, the authors of the study theorize that the end result would be that because patients tend to develop brand loyalty, patients who were prescribed the more expensive drugs more often than the cheaper or OTC medications stand to spend more over time.

"This could be especially burdensome for low-income patients," Adair wrote.

Cost of free’ samples questioned

A post hoc analysis considering only drugs commonly used for short-term therapy (nonsteroidal anti-inflammatory drugs [NSAIDs] including cyclooxygenase-2 [COX 2] inhibitors, proton pump inhibitors, and H2 blockers) showed that access to samples of these drugs seemed to be especially influential, associated with less use of inexpensive drugs (63/126, 74/115; P = .02), OTC drugs (53/126, 71/115; P = .002), and generic drugs (70/126, 80/115; P = .02). There was little difference in use of unadvertised drugs (89/126, 87/115).

Access to drug samples influenced prescribing decisions of resident physicians — something that Adair wrote "would seem to violate published national guidelines on physician interactions with the pharmaceutical industry," and furthermore, the physicians observed in the study tended to underestimate their personal response to marketing.

"This finding contradicts two widespread beliefs: Drug samples are inherently different from other forms of marketing, and samples help patients manage drug costs in the long term," Adair reported.

Researchers conclude that the findings raise questions about whether drug samples should have a place in clinics where residents are learning or low-income patients are receiving care.

"Other studies have shown that many Americans do not take prescribed medications because they cannot afford them," wrote Adair. "Whether to provide free’ samples of expensive drugs to these patients is an ethical dilemma for many doctors."

For more on the study, see Adair RF, Holmgren LR. Do drug samples influence residents prescribing behavior? A randomized trial. Am J Med 2005; 118:881-884.