I haven't seen modelling on the effects of direct-to-consumer advertising in Canada. There certainly have been a number of studies in the U.S. The National Institute for Health Care Management, for instance, looked at annual increases in retail drug costs. They found that approximately half were due to the 50 drugs that were being advertised to the public--this was between 1999 and 2000--and the other half were due to the 10,000 additional other drugs. They certainly saw a large association between those two.
In the study I did in physicians' offices--in both a Canadian setting, in Vancouver, and in a U.S. setting, in Sacramento--I certainly saw an effect on volume of prescribing in individual consultations. If a person asked for a specific advertised drug, three-quarters of the time they walked out of that consultation with that specific prescription. They also almost always had at least one new prescribed product. Other patients, around one-third of the time, had a new prescription. So there certainly was an effect, in terms of volume.
I could go on about other research evidence.
Also, in terms of volume, say, of off-label prescribing of a drug, there was a study done in the U.S. that looked at off-label prescribing. It looked at whether physicians prescribed an antidepressant that was being heavily advertised to patients who came in with a normal life situation versus clinical depression--whether they had asked for the drug or not. If they had asked for the advertised brand, they were much more likely, with a normal life situation, to end up with a prescription for an antidepressant.