Face-to-face promotion to doctors by pharmaceutical representatives is far more effective than direct-to-consumer advertising (DTCA) of prescription drugs, a study by US and Canadian researchers has concluded.

"People tend to think that if DTC advertising wasn't effective, pharma wouldn't be doing it. But as it turns out, decisions to market directly to consumers is based on scant data,” said Harvard Medical School (HMS) professor Stephen Soumerai, principal investigator for the first-ever controlled study into DTCA.

Spending on DTCA - which is legal only in the USA and New Zealand - soared 330% in the 10 years since the US Food and Drug Administration (FDA) lifted its ban on the practice in 1997, and currently stands at more than $5 billion. In 2006, the US Government Accountability Office (GAO) reported that every $1 spent on DTCA generates an average $2 in sales.

However, to discover whether prescription drugs which sell the most are simply those which are advertised the most, the researchers, from HMS and the University of Alberta, compared the effects of advertising on two groups of consumers in Canada. DTCA is illegal there, but English-speaking Canadians are as inundated with such ads – through television, radio and magazines originating from the USA – as Americans, who typically watch an average of nine DTC drug ads each day. However, in the Canadian province of Quebec, French is the first language for about 80% of the population, and they tend to get most of their news from French-language media, so the researchers chose Quebec as a control group.

“It’s not an absolutely perfect control group,” acknowledged Michael Law, first author on the paper. "There's obviously a small percentage of Quebec residents who are exposed to English language media. But as control groups go for this sort of observational study, it's about as good as you get,” he said.

The study compared prescription rates in English-speaking Canadian provinces with rates in Quebec for three advertised drugs: Amgen/Wyeth’s rheumatoid arthritis treatment Enbrel (etanercept), Schering-Plough’s Nasonex (mometasone) for nasal allergies and Novartis’ Zelnorm (tegaserod) for irritable bowel syndrome (now withdrawn). All three drugs were on the market for at least a year before their DTCA campaigns began, and none were advertised in Canada through "softer" consumer ads, which allow the drug to be named if the relevant conditions are not identified.

An analysis of prescription data from 2,700 pharmacies supplied by IMS Health over a five-year period found that, for the Enbrel and Nasonex, the $194 million and $235 million spent respectively on DTCA campaigns had no effect whatsoever. Prescription patterns in English-speaking Canada and in Quebec remained identical both before and after DTCA campaigns began.

However, Zelnorm’s sales did spike noticeably in English-speaking Canada as soon as its $314 million DTCA campaign began, with prescriptions rising more than 40%. However, this increase was relatively short-lived, and prescription rates in both groups resumed identical patterns after a few years. A similar analysis of US Medicaid prescriptions for the drug found a slightly higher, but similarly brief, jump in sales.

Reporting their results on-line in the British Medical Journal (BMJ) on September 2, the researchers suggest that DTCA may not be as effective as other types of consumer advertising because of the unique complexity of the marketing/sales trajectory.

With a typical consumer product, an individual sees an ad and then can choose to simply go out and buy it, noted Prof Soumerai. However, in the case of medicines, “a person needs to see an ad, get motivated by that ad, contact their doctor for an appointment, show up at the appointment, communicate both the condition and the drug to the doctor, convince the doctor that this drug is preferable to other alternatives, then actually go out and fill the prescription. This is a chain of events that can break at any point,” he said.

This may explain the varying effects of DTCA discovered for the three drugs. While there are a number of over-the-counter (OTC) and prescription alternatives for Enbrel and Nasonex that doctors would likely recommend as first-line treatments, Zelnorm was the only drug available in both the US and Canada for constipation-predominant irritable bowel syndrome, and the drug would have sold very well without the DTCA, the authors suggest.

- Critics are also concerned at the recent rise of “unbranded product advertising” for brand-name drugs on US television, which takes advantage of FDA regulations stating that ads which do not name the drug directly do not have to list its side-effects. The new ads simply direct the viewer to a website which promotes the product, and does list its side effects.