Docs not immune to drug marketing, study finds

The findings, published in the open-access journal PLoS Medicine and led by University of Queensland professor Geoffrey Spurling, offer a broad look at the relationship between doctors' prescribing habits and their exposure to information provided by drug companies. Researchers analyzed 58 separate studies of this phenomenon from Canada, the United States, Europe and Australia, dating from the 1960s.

"Many doctors claim they aren't influenced by the information provided by pharmaceutical companies. Our research clearly shows that they are -- and the influence is negative," says study co-author Joel Lexchin., a professor in the School of Health Policy & Management in York's Faculty of Health and an emergency physician in Toronto.

"Unfortunately, patients are the ones getting a raw deal. If doctors are inundated with advertising from brand name companies, they are more likely to prescribe that brand name, regardless of whether it's best for the patient," Lexchin says.

Overall, researchers found no evidence that drug companies' promotional efforts improve prescribing behaviour in any way. All but one of the studies suggested that exposure to promotional information was associated with lower prescribing quality; others detected no association. Findings also show that promotional information led to more frequent prescribing; studies dealing with this correlation either showed a spike in prescribing or detected no association. Researchers also established a link between promotion and higher prescribing costs.

Lexchin says Canadian drug companies spend big money on marketing their products to physicians, to the detriment of other priorities such as research and development.

"In Canada, companies are estimated to be spending anywhere between $2.4 and $4.75 billion annually on promotion, one of the major reasons why spending on brand name drugs was rising at a rate of just under 10 per cent annually until two years ago," he says.

A limitation of the research is that most studies were observational in nature, meaning that the majority of physicians who participated were not randomly selected.

"Although we didn't find any evidence of improvements in prescribing due to promotional information, that doesn't entirely exclude the possibility that prescribing might sometimes be improved," Lexchin says. "As a precaution, we recommend that physicians avoid exposure to the information provided by pharmaceutical companies."