Is content of medical journals related to advertisements? Case-control study.

AIM To assess the relatedness of journal content to paid advertisements published in the journal. METHODS The case-control study was performed on a convenience sample of 7 journals subscribed by Central Medical Library in Moscow--4 international (American Journal of Hypertension, British Journal of General Practice, The Lancet, and New England Journal of Medicine) and 3 Russian peer reviewed journals (Terapevticheskii Arkhiv, Khirurgiia, and Voeno-Meditsinskii Zhurnal). In each issue containing a paid advertisement, classifieds excluded, we searched for articles related to the advertised product and compared this issue with a control issue - the next or a later issue without this advertisement. RESULTS In American Journal of Hypertension (33 issues from 2002-2004) 94 placements of advertisements were found, 7 of which were closely related to the article topic in the same issue (7/94) vs 2/66 in the control issue. The odds ratio (OR) and 95% confidence interval (CI) for advertisements to be accompanied by related articles was OR, 2.6; 95%CI, 0.5-13). In British Journal of General Practice (27 issues from 2003-2005) there were 7/63 advertisements related to the article topic vs 0/28 in the control issue (OR, 7.2; 95% CI, 1.3 to 44). In The Lancet (49 issues from 2004) there were 8/162 advertisements related to the article topic vs 8/104 in the control issue (OR, 0.6; 95% CI, 0.3-1.5). In New England Journal of Medicine (37 issues from 2004) there were 12/81 advertisements related to the article topic vs 8/75 in the control issue (OR, 1.5; 95% CI, 0.56-3.79). In Terapevticheskii Arkhiv (10 issues from 2004) there were 38/93 advertisements related to the article topic vs 1/83 in the control issue (OR, 56.66; 95% CI, 4.4-253). In Khirurgiia (25 issues from 2003-2005) there were 3/83 advertisements related to the article topic vs 0/70 in the control issue (OR, 2.7; 95% CI, 0.3-26). In Voeno-Meditsinskii Zhurnal (33 issues from 2003-2005) there were 17/31 advertisements related to the article topic vs 2/31 in the control issue (OR,17.6; 95% CI, 3.6-87). CONCLUSIONS The strong relatedness between the content of the articles and advertisements placed in 3 of 7 journals and explicit placement of the advertisements face to face or overleaf the related research articles support the hypothesis that journal content is manipulated to place more emphasis on the advertisements.