This post courtesy of Anne Taylor-Vaisey:
This study published in the February 15 issue of CMAJ caught my eye because I used to be involved in verifying citations for CHE work associated with pharmaceutical companies. This was during my year with a communications company, and we were meticulous about proper use and citation of the literature. But I have often seen questionable references in drug ads, and on a couple of occasions I have searched for the articles cited and have been unable to locate them, based on the references supplied.
This study's authors reviewed drug ads from selected medical journals from 1999 and concluded:
a) many advertised claims are not supported by cited literature;
b) a large number of references are of the data-on-file kind of material and therefore unobtainable by clinicians; and
c) the majority of literature cited in ads is funded by the manufacturers of the drugs advertised, directly or indirectly.
The ads studied were from 1999. It would be interesting to see whether this practice has changed in recent years. If not, the results are discouraging, I think.
Cooper RJ, Schriger DL. The availability of references and the sponsorship of original research cited in pharmaceutical advertisements. CMAJ 2005; 172(4):487-491.
Background: The primary goal of pharmaceutical advertisements is to convince physicians to prescribe the manufacturer's product. We sought to determine what materials are cited in support of claims in pharmaceutical ads and medical research articles, and whether health care professionals seeking to verify the claims could obtain these references.
Methods: We reviewed 438 unique ads from the 1999 issues of 10 American medical journals, and a random sample of 400 references in medical research articles selected from the same journals. We classified references as journal article, dat! a on file, meeting abstract or presentation, book or monograph, report, prescribing information, government document or Internet site. We attempted to confirm or obtain each reference through library and Internet searches or by direct request from the manufacturer. The main outcome we sought to determine was the availability of the reference to a clinician. We also ascertained the source of funding for original research cited in the ads and the research articles.
Results: In the 438 ads with medical claims, 126 contained no references and 312 contained 721 unique references. Of these ad references, 55% (396/721) cited journal articles and 19% (135/721) cited data on file. In contrast, in the sample of research article references, 88% (351/400) cited journal articles and 8% (33/400) cited books. Overall, 84% of the citations from the ads were available: 98% of journal articles, 86% of books, 71% of meeting abstracts or presentations and 20% of data-on-file re! ferences. In all, 99% of the sample of research article references were available. We determined that 58% of the original research cited in the pharmaceutical ads was sponsored by or had an author affiliated with the product's manufacturer, as compared with 8% of the articles cited in the research articles.
Interpretation: Many pharmaceutical ads contain no references for medical claims. Although references to journal articles were usually obtainable, other published sources were not as easily acquired. The majority of unpublished data-on-file references were not available, and the majority of original research cited to substantiate claims in the pharmaceutical ads was funded by or had authors affiliated with the product's manufacturer.
Free full text: http://www.cmaj.ca/cgi/reprint/172/4/487