The influence of advertising on drug recommendations

Little is known about corporate influence on educational medical journals, although physicians rely heavily on journals for continuing medical information. Many of these journals, which rely solely on advertising for revenue and contain easy-to-read summaries of published research, are sent free to physicians in countries around the world.

The study, by German and Canadian researchers, looked at 11 different journals read by German physicians in 2007. They largely compared free journals -- those paid solely by advertising -- to journals funded by subscriptions. One mixed revenue journal was included in the study.

"Our study shows that the tendency to positively recommend the use of a drug depends on the source of a journal's funding," writes Dr. Annette Becker, University of Marburg, Marburg, Germany, with coauthors. "Free journals almost exclusively endorse the use of the selected drugs, whereas journals that rely exclusively on subscription fees for their revenue are more likely to recommend against the use of the same drugs. A survey of Canadian general practitioners found that they were unlikely to consider journals that did not undergo a peer review process (typically those journals sent to them free of charge) as credible sources of information. However, more than half of the doctors surveyed had used free journals as a source of information during the previous month."

Physicians need to be aware of these biases when using medical education materials in free medical publications.

The authors conclude that physicians have a choice to pay for journals that provide objective information or rely on potentially biased information in free journals.

In a related commentary, Dr. Aaron Kesselheim, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, writes "the results reported by Becker and colleagues are nonetheless salient. Covert promotion of pharmaceuticals is an important public health issue because it can contribute to the unnecessary overuse of certain drugs or lead to their off-label use without sufficient evidence of efficacy."