Few Canadians are taking a controversial new cholesterol-lowering drug compared with millions in the United States, where the medication has been heavily promoted, according to a new study that suggests advertising may have a greater influence on the use of a medication than scientific evidence.
More than 33 million prescriptions for ezetimibe, sold under the brand names Zetia, Ezetrol and Vytorin, were issued in the United States in 2006, compared with just 824,000 in Canada during the same period.
The drug accounted for more than 15 per cent of all prescriptions for cholesterol-lowering medication in the United States that year, but only 3.4 per cent in Canada.
The results of the study, conducted by Toronto's Institute for Clinical Evaluative Sciences, Connecticut's Yale University and California's Western University of Health Sciences, were published online Sunday by The New England Journal of Medicine.
Ezetimibe is not recommended by health authorities as the first option for patients seeking to control cholesterol in Canada or the United States, according to the study, and has been the subject of growing debate over its effectiveness compared with other medication.
That has led researchers to believe that other factors - particularly heavy promotion to U.S. consumers - have contributed to its rapid sales growth in that country and its sluggish performance here.
In Canada, drug companies are not allowed to directly advertise a medication and its benefits to the public, but they can promote their products to physicians.
They have much more freedom to publicly promote drugs in the United States, which many medical experts say has a major impact on the types
of medications that are being prescribed.
The study provides a significant glimpse of the possible impact of direct-to-consumer advertising that comes as the Supreme Court of Canada is deciding whether to lift restrictions here.
"I think this example serves as a cautionary tale, about the potential downsides of that practice," should it be legalized in Canada, said Jack Tu, lead author of the study and a senior scientist at the Institute for Clinical Evaluative Sciences.
"It has broader implications beyond this specific example," Dr. Tu said.
"It shows the potential downsides to ... too much advertising, without the evidence behind it."
The study said that more than $200-million (U.S.) was spent on direct-to-consumer advertising for Vytorin in 2007 and that sales of the drug recently eclipsed $5-billion.
Many medical experts and consumer advocates worry that direct-to-consumer advertising will result in patients asking their doctors for prescriptions for heavily promoted drugs even though the medications may not be the best health choice.
Dr. Tu said the new study may provide some credence to that theory, considering ezetimibe prescriptions skyrocketed in the United States even though it has less clinical data than other cholesterol-lowing drugs.
"I think there's some real serious risks, both in increasing the costs to the health care system and exposing patients to interventions where there isn't as much scientific data behind it as there should be," he said.
In the study, researchers examined data for prescriptions of all cholesterol-lowering drugs in Canada and the United States from January, 2002, to December, 2006. They found that prescriptions for cholesterol drugs rose in both countries during the study
period.
Advertising may be one factor contributing to the success of ezetimibe, but differences in drug availability and insurance coverage also contributed to its popularity in the United States, Dr. Tu said.
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