Medical school policies that restrict gifts to physicians from the pharmaceutical and device industries are becoming increasingly common, but the effect of such policies on physician prescribing behaviour after graduation into clinical practice is unknown.

So a team of US researchers set out to examine whether attending a medical school with a gift restriction policy affected subsequent prescribing of three newly marketed psychotropic (stimulant, antidepressant, and antipsychotic) drugs.

They identified 14 US medical schools with an active gift restriction policy in place by 2004.

They then analysed prescribing patterns in 2008 and 2009 of physicians attending one of these 14 schools compared with physicians graduating from the same schools before the policy was implemented, as well as a control sample of 20 schools that only adopted a gift restriction policy in 2008.

For two of the three drugs examined, attending a medical school with an active gift restriction policy was associated with reduced prescribing of the new drug over older alternatives within the same drug class.

A significant effect was not seen for the third drug.

Among students who had a longer exposure to the policy, or were exposed to more stringent policies, prescribing rates were further reduced.

"Our findings suggest that conflict of interest policies, which have been increasingly adopted by medical schools since 2002, may have the potential to substantially impact clinical practice and reduce prescribing of newly marketed pharmaceuticals," say the authors.

They add: "Future research examining the effect of these policies on medications with varying levels of innovativeness is necessary to establish whether medical school gift restriction policies reduce prescribing of all newly marketed medications or affect prescribing selectively."