Psychiatrists who are exposed to conflict-of-interest (COI) policies during their residency are less likely to prescribe brand-name antidepressants after graduation than those who train in residency programmes without such policies, new US research has shown.

The study is the first of its kind to show that exposure to COI policies for physicians during residency training - in this case psychiatrists - is effective in lowering their post-graduation rates of prescriptions for branded medications, including heavily-promoted and brand reformulated antidepressants, say the researchers, from the Perelman School of Medicine at the University of Pennsylvania, who report their findings in the journal Medical Care.

Use of antidepressants in the US increased nearly 400% from 1988 to 2008, and the research focused on these medicines because they have been among the most heavily-marketed drug classes, said Andrew Epstein, research associate professor of medicine at the Perelman School and first author on the study.

In 2008, the Association of American Medical Colleges developed COI policy guidelines for gifts, free meals and medication samples provided by pharmaceutical companies to physicians and trainees, and in 2006, Penn Medicine - the academic medical centre of which the Perelman School is part - implemented policies placing restrictions on physician interactions with drug company representatives.

The concern was that these interactions could influence clinicians to prescribe branded medications, even if they were more expensive or less suitable for patients than generic alternatives, say the researchers.

To assess the effects of COI policies on physicians' prescribing patterns after residency, the researchers examined 2009 prescribing data from IMS Health for 1,652 psychiatrists from 162 residency programmes. The doctors fell into two categories; about half graduated residency by 2011, before COI training guidelines were implemented, while the other half graduated in 2008, after many medical centres had adopted such policies. The physicians were also categorised based on the restrictiveness of the COI policies adopted by their residency programmes' medical centres.

The results of the study show that, although rates of prescribing for brand-name antidepressants - including those that were heavily promoted and brand reformulations - were lower among 2008 graduates than 2001 graduates in general, the rates were lowest for 2008 graduates of residency programmes with very restrictive COI policies.

These findings suggest that COI policies reduce the appeal of antidepressant medications marketed heavily by pharmaceutical companies, and because brand-name medications tend to be more expensive, a shift away from them could help reduce cost growth, says Dr Epstein. However, he also warns that lower costs achieved through stringent COI policies may come at a price.

"Contact with the pharmaceutical industry may have important information benefits for physicians. And, by exposing trainees to industry representatives, we may be helping them prepare to navigate these relationships after graduation," he says.

Nevertheless, he adds that: "while these relationships may be useful in some ways, our study clearly shows that implementation of COI policies have helped shield physicians from the often-persuasive aspects of pharmaceutical promotion."

The study provides the first empirical evidence of the effects of such policies, and Dr Epstein says that in future research it will be critical to assess whether they have similar effects on other drug classes and physician specialties as the study shows that they have on the prescribing of brand-name antidepressants.