The pharmaceutical industry increasingly uses bibliographical references to clinical trials that endorse their products in advertisements-mainly due to pressure from the evidence-based medicine movement concerning the prescribing behaviour of doctors. Salvador Peiró from the Valencia School for Health Studies, Spain, and colleagues assessed whether the references about efficacy, safety, convenience, or cost of antihypertensive (blood-pressure lowering) and lipid-lowering drugs included in advertisements supported the promotional claims.
All advertisements for antihypertensive and lipid-lowering drugs published in six Spanish medical journals in 1997 that had at least one bibliographical reference were assessed. Two pairs of investigators independently reviewed the advertisements to see whether the studies quoted to endorse the advertising messages supported the corresponding claims.
Nearly half-44%-of 102 promotional claims analysed were not supported by corresponding references. The most common error in advertising was the recommendation of drug treatment to a different group of patients to those assessed in the reference study.
Salvador Peiró comments: "Doctors should be cautious in assessment of advertisements that claim a drug has greater efficacy, safety, or convenience, even though these claims are accompanied by bibliographical references to randomised clinical trials published in reputable medical journals and seem to be evidence-based."
In an accompanying Commentary (p 10), Robert H Fletcher from Harvard Medical School, Boston, USA, concludes: "Readers should not take claims in journal adverts, with or without credible-appearing references, on face value. Regulation of advertising claims is not strong or consistent enough to protect readers from misinformation. But then, neither should readers accept the conclusions of original research uncritically. Government regulators and editors do attempt to improve the accuracy of the content of medical journals, both articles and adverts. But readers must still take personal responsibility for judging the validity of assertions, especially those made in adverts."
Journal
The Lancet