Spending on direct-to-consumer advertising of prescription drugs continues to rise, but a new study suggests it might not always be a wise investment.
Drug companies spent an estimated $4.24 billion on direct-to-consumer, or DTC, ads in 2005 -- more than triple what they spent in 1996, but still far less than what they spend on marketing to doctors, researchers report today in the journal BMJ.
Critics argue that DTC ads lead to inappropriate prescribing because patients demand drugs they saw on TV. But do drug ads have the same effect as, say, detergent ads? "Drugs are a very different product from most consumer goods," says Michael Law, lead author of the new study, part of his doctoral dissertation in health policy at Harvard.
Teasing out the impact of DTC ads from that of marketing directed at doctors is tricky. Law and his co-authors looked to Canada for help.
Although Canada, like every other country except the USA and New Zealand, bans DTC drug ads, residents regularly see "illicit" ads on U.S. cable and satellite TV stations. But while previous research suggested that 85% of English-speaking Canadians had recently seen a drug ad, French-speaking Canadians watch far less American TV.
Law and his co-authors identified three drugs that had been approved for use in Canada before their DTC ad campaigns were launched.
The scientists then compared prescription rates before and after the ads began and analyzed differences between the mainly English-speaking provinces and Quebec, where French is the mother tongue for more than 80% of the population.
For two of the drugs studied -- Enbrel for rheumatoid arthritis and psoriasis, and Nasonex for allergy symptoms -- they found no statistically significant changes after DTC ads were launched in either the English-speaking provinces or in Quebec, suggesting the ads had no effect.
The scientists did find a temporary rise in the English-speaking provinces in prescriptions for Zelnorm for irritable bowel syndrome. Zelnorm, approved in 2002, came off the market in 2007 after it was linked to increased risks of heart attack, stroke and severe chest pain.
DTC ads do "a good job of driving people into the doctor's office, raising awareness of symptoms that the patient might have," but they might not result in a prescription for the drug being promoted, says Lori Reilly, vice president for policy and research at the Pharmaceutical Research and Manufacturers Association, an industry group. Instead, Reilly says, patients might get a prescription for a generic drug or none at all.
"If you're the fourth, fifth or sixth cholesterol-lowering medication, it does not pay to advertise," says Julie Donohue, a University of Pittsburgh health policy researcher.
The rise in Zelnorm prescriptions probably reflected the fact that it was the only approved drug for irritable bowel syndrome, Donohue and Law say.
But Zelnorm fell to its pre-DTC prescribing levels within two years after the ads started airing, Law's study found. Says Donohue: "No amount of advertising is going to be able to sell a drug that doesn't work very well."
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