The strategy of advertising directly to the final consumer of the product may not be the best way to do it in the case of drug companies, and most of them aren’t aware of this fact yet.

According to a recent study published in the online “British Medical Journal,” the billions-worth, direct-to-consumer advertising campaigns used by most drug companies have a small effect. Advertising drugs directly to consumers is allowed only in the United States and New Zeeland. The ban was lifted in the U.S. in 1997.

With advertising expenses of nearly $5 billion per year, the pharmaceutical industry should have known this already. They have been spending so much on direct-to-consumer campaigns believing that the strategy increases prescriptions.

The study carried out by a group of researchers in Canada (where that kind of campaign is illegal) used the disparity between the English-speaking Canadians (more exposed to the advertising campaigns from the U.S.) and the French-speaking Canadians. Three drugs were included in the study: Enbrel (for rheumatoid arthritis), Nasonex (for nasal allergies), and Zelnorm (for irritable bowel syndrome).

By studying prescription stats over 5 years using data provided by IMS Health Canada, researchers found out that sales of Enbrel and Nasonex remained unchanged despite the direct-to-consumer (DTC) advertising. The only impact the ad campaign had was on sales of Zelnorm which rose 40% among the English-speaking Canadians, but only for a few years after which sales were the same among the two groups.

"Decisions to market directly to consumers [are] based on scant data," says Stephen Soumerai, a Harvard Medical School professor and study researcher.

The study involved data gathered from 2,700 pharmacies.