WASHINGTON DC: A new study by Harvard Medical School is set to cause a stir in the controversial world of direct-to-consumer advertising of prescription drugs, with its claim that billions of pharma dollars spent on such messages have little impact on sales.

The report comes as US health lobbyists are pressing for legislative curbs on the annual $4.8 billion (€3.3bn; £2.7bn) DTC ad industry, while the latter is fighting equally hard to demonstrate that self-regulation is sufficient.

The Food and Drug Administration is currently reviewing its rules ( and under pressure to tighten them), while regulators in the European Union and Canada are considering allowing DTC ads to  appear on television and in print.

The new report, co-authored by Harvard professor Stephen Soumerai and which appeared in the prestigious British Medical Journal, compares the behavior of people exposed to drug ads with people who were not.

The researchers studied a control group in Canada's French-speaking province of Quebec. These are North Americans who spend less than five percent of their TV time tuned to US channels, where DTC drug ads are ubiquitous.

They compared prescribing behavior in Quebec with Canada's English-speaking provinces - where viewers spend around 30% of their viewing time on American channels.

The results showed that during two major ad campaigns - for an arthritis treatment and an anti-allergy medicine - there was no change in the difference between per capita usage in Quebec and English-speaking parts of Canada.

During a third campaign, for Novartis' (now withdrawn) Zelnorm, usage in English-speaking Canada briefly exceeded Quebec, then settled back.

Concludes Soumerai uncompromisingly: "Direct consumer advertising is really a lousy way to influence prescribing."

He concedes: "Some advertising probably works," but "it was pretty unimpressive, on the whole, across three drugs."

The researchers now plan to extend the study across more products.

Ad industry spokesman have been quick to rubbish the study. Declared pharma consultant Mel Sokotch: "To conclude that DTC doesn't work based on the US advertising that spills into Canada is flawed."

While his inspired compadre Sander Flaum asked rhetorically: "Had anyone ever heard of erectile dysfunction or overactive bladder before the drugs were advertised?"

Data sourced from Wall Street Journal Online; additional content by WARC staff