Direct-to-consumer drug ads' effect seen as mixed despite billions spent

A novel study design allowed researchers to examine the effectiveness of television ad campaigns promoting the use of three drugs.

By Susan J. Landers — Posted Sept. 22, 2008

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A great deal of physicians' time, pharmaceutical companies' money and policymakers' attention is spent on direct-to-consumer drug advertising. But do these ads really make a difference in drug sales? A new study came to the surprising conclusion that they might not.

A team of Harvard researchers determined that the effect of DTC ads on the sales of three drugs varied. For two of the drugs, no spike in prescriptions was detected after an advertising campaign began airing on television. But the researchers noted a short-lived uptick in prescriptions written for a third drug, Zelnorm, or tegaserod, when its DTC first began in 2003. Zelnorm was removed from general sales in the U.S. last year and is currently available only for very limited use.

The study was published online Sept. 2 in the British Medical Journal.

Pharmaceutical companies have spent billions of dollars each year on DTC ads ever since the Food and Drug Administration removed restrictions in 1997, and their proliferation has sparked physician concern about the ads' influence on prescribing patterns. The American Medical Association developed guidelines for DTC ads and has long sought better federal oversight of their content.

Common wisdom has held that drug firms have evidence the ads promote sales, but no one has been able to confirm this using a randomized controlled trial to assess their impact, the researchers said.

"People tend to think that if direct-to-consumer advertising wasn't effective, 'pharma wouldn't be doing it,' " said Stephen Soumerai, ScD, professor in the Dept. of Ambulatory Care and Prevention at Harvard Medical School and an author of the study. "But as it turns out, decisions to market directly to consumers are based on scant data."

Study design crosses borders

Since the drug ads permeate the airwaves, researchers had to take a novel approach to find a large control group that has not been exposed to them. DTC ads are illegal in Canada, but since U.S. television signals carry the ads across the border, the Harvard researchers used French-speaking Canadians living in Quebec as their controls.

They compared the number of prescriptions filled by Canadians in English-speaking provinces, who are known to watch a great deal of U.S. television, to prescriptions filled by French speakers, who watch very little American TV.

They found that prescription rates for Enbrel, or etanercept, a drug used for rheumatoid arthritis, and Nasonex, or mometasone, an allergy medication, did not increase in English-speaking -- and American TV-viewing -- provinces relative to French-speaking Quebecers.

On the other hand, prescriptions for Zelnorm did increase among English speakers as soon as ads began airing. After a few years, however, Zelnorm prescription rates for both groups resumed identical patterns.

Researchers concluded that the impact of DTC advertising is mixed, working for some drugs but not others. With the results, "profits may be better spent elsewhere," they write.

Some say study was too limited

But other researchers who have studied DTC ads are viewing the findings with even more caution. "It's very difficult to generalize from a study of three drugs," said Julie Donohue, PhD, assistant professor of health policy and management at the University of Pittsburgh's Graduate School of Public Health. Donohue was the lead author of a review of DTC ads published last year in the New England Journal of Medicine.

"Advertising is a tricky business," she added. "There are a lot of factors intervening between the advertiser and the consumer getting the drug. Insurance company and physician preferences are going to affect demand."

Dominick Frosch, PhD, assistant professor of general internal medicine at the University of California, Los Angeles, also cast a skeptical eye at the findings. "What I always come back to is: Why on earth would publicly traded companies, who are responsible to their shareholders, spend $5 billion on advertising if it doesn't work? We are talking about a fair amount of money here."

He is now examining DTC ads and their effect on consumers.

In reality, drug firms may not know a lot about what works in promoting drugs, Soumerai said. When his earlier research demonstrated the effectiveness of drug detailing, he was told by drug firm representatives that the information was useful to them. "So we are realizing that when drug companies do these things, they don't have controlled studies."

Ken Johnson, senior vice president of the Pharmaceutical Research and Manufacturers of America, a Washington, D.C.-based trade group that represents large pharmaceutical and biotechnology firms, said he wasn't surprised by the findings, but that ads can open the door for a discussion between physician and patient. "DTC advertising can be a valuable source of patient education," he said.

Some critics contend that ads unduly influence physicians' prescribing practices, Johnson said. "This study reveals that DTC advertising does not have a significant impact on physician prescribing rates."

Soumerai also noted the findings that doctors weren't swayed in their prescribing habits by patients bearing messages from TV ads.

But, Soumerai observed, though the ads are costly -- an estimated $5 billion per year -- and seemed to have only limited success, they still take up physicians' already limited time with patients to discuss medications that may not be needed.

The ads "result in hassles for doctors who already don't have time to do what they are trained to do," Soumerai said.

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Study at a glance

What is the impact from direct-to-consumer advertising?

A study published online Sept. 2 by the British Medical Journal assessed the impact of DTC advertising of three heavily marketed drugs: etanercept, mometasone and tegaserod.

Methods: Researchers measured differences in the number of filled prescriptions for English-speaking and French-speaking Canadian provinces before and after the start of DTC advertising campaigns in the U.S. DTC advertising is illegal in Canada, so it is not shown on French-language television. But it can be seen there on English-language television stations originating in the U.S.

Results: Prescribing rates of etanercept and mometasone did not increase in English-speaking provinces. Tegaserod prescriptions increased 42% in English-speaking provinces immediately after the start of the campaign, but the increase did not persist over time.

Conclusion: Researchers determined that the impact of DTC advertising on prescribing rates and prescription drug use seems highly variable and probably depends on the characteristics of the advertised drug, the level of consumers' exposure to the ads and the cultural context.

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External links

"Effect of illicit direct to consumer advertising on use of etanercept, mometasone, and tegaserod in Canada: controlled longitudinal study," abstract, British Medical Journal, Sept. 2 (link)

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