DTC Drug Ads May Have Little Effect, Study Says


Direct-to-consumer advertising may have a limited effect on demand for medication, based on analysis of Canadians exposed to U.S. advertising published online.

Researchers from Harvard Medical School, Boston, and University of Alberta, Edmonton, found that the introduction of U.S. advertising campaigns for etanercept (Enbrel) and mometasone (Nasonex)—to which English-speaking Canadians were exposed through broadcast, print, and online media—did not cause a statistically significant change in prescribing patterns in English-speaking areas, when compared with French-speaking areas of Canada, where exposure was limited (BMJ 2008;337:a1055 [doi:10.1136/bmj.a1055

An advertising campaign for tegaserod (Zelnorm), however, did cause a statistically significant increase in English-speaking areas. “People tend to think that if direct-to-consumer advertising wasn't effective, [pharmaceutical companies] wouldn't be doing it,” investigator Dr. Stephen Soumerai, professor of ambulatory care and prevention at Harvard, said in a statement. “But as it turns out, decisions to market directly to consumers [are] based on scant data.”

Dr. Soumerai and his colleagues studied Canadians because although direct-to-consumer advertising is illegal in Canada, English speakers close to the border are exposed to U.S. advertising. About 30% of television watched by English-speaking Canadians is foreign sourced, the researchers said, citing Statistics Canada data.

But because the advertising is in English, French speakers can serve as a control group because they view much less foreign-sourced media—about 5%, the researchers said.

Consulting data from IMS Health Canada, the researchers said they detected no statistically different changes in prescribing patterns in English- and French-speaking provinces following the January 2003 introduction of U.S. direct-to-consumer advertising for etanercept and the December 2004 start of the campaign for mometasone. But, for tegaserod, prescribing rates grew 42% in English-speaking provinces in the first month after the start of an August 2003 campaign, according to the researchers. The trend was not sustained, and within 2 years, tegaserod prescription rates were the same in both English- and French-speaking provinces, the researchers said. Furthermore, the trend in Canada was not as pronounced as in the U.S. Medicaid program, which saw its prescribing of tegaserod rise 56%, the researcher wrote. Tegaserod since has been withdrawn from the market.

The researchers acknowledged that their findings may not be generalizable to other drugs advertised directly to consumers. They added that differences in drug coverage, exposure to advertising, television viewing patterns, culture, and the health care system at large may have had an effect on their findings.

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