In one of the largest studies of its kind, UCLA investigators reviewed pharmaceutical ads in American medical journals to determine what materials are cited in support of medical claims and if those references are available to physicians. Researchers also determined the funding sources of research cited in the ads.
The study is published in the Feb. 15 issue of the Canadian Medical Association Journal.
"Previous studies have shown that physicians' drug prescribing is influenced by pharmaceutical ads. We wanted to see what documents were being used to substantiate the claims and how accessible these were to physicians who may want to verify the research findings," said lead author Dr. Richelle Cooper, assistant clinical professor, Division of Emergency Medicine, David Geffen School of Medicine at UCLA.
Two UCLA investigators independently reviewed 438 ads from 10 American medical journals from 1999 and also reviewed a random sample of 400 references in journal articles from the same publications for comparison.
Researchers found that out of 438 pharmaceutical ads, 126 (29 percent) offered no references in support of medical claims. The most commonly cited references in the ads included journal articles (55 percent) and data-on-file (19 percent), which is a reference to an unpublished company document. Other sources included books; prescribing information such as the Physician's Desk Reference, which annually provides information on drug usage, warnings and drug interactions; government documents; or an Intern