Lundh et al. . 2010. Conflicts of Interest at Medical Journals: The Influence of Industry-Supported Randomised Trials on Journal Impact Factors and Revenue - Cohort Study. PLOS MEDICINE 7 (10): art. no.-1000354.

[Eugene Garfield]

Lundh, A; Barbateskovic, M; Hrobjartsson, A; Gotzsche, PC. 2010. Conflicts of 
Interest at Medical Journals: The Influence of Industry-Supported Randomised 
Trials on Journal Impact Factors and Revenue - Cohort Study. PLOS MEDICINE 
7 (10): art. no.-1000354.

Author Full Name(s): Lundh, Andreas; Barbateskovic, Marija; Hrobjartsson, 
Asbjorn; Gotzsche, Peter C.

Language: English
Document Type: Article

KeyWords Plus: PHARMACEUTICAL COMPANIES; AUTHORSHIP; DOCUMENTS

Abstract: Background: Transparency in reporting of conflict of interest is an 
increasingly important aspect of publication in medical journals. Publication of 
large industry-supported trials may generate many citations and journal income 
through reprint sales and thereby be a source of conflicts of interest for 
journals. We investigated industry-supported trials' influence on journal impact 
factors and revenue.
Methods and Findings: We sampled six major medical journals (Annals of 
Internal Medicine, Archives of Internal Medicine, BMJ, JAMA, The Lancet, and 
New England Journal of Medicine [NEJM]). For each journal, we identified 
randomised trials published in 1996-1997 and 2005-2006 using PubMed, and 
categorized the type of financial support. Using Web of Science, we 
investigated citations of industry-supported trials and the influence on journal 
impact factors over a ten-year period. We contacted journal editors and 
retrieved tax information on income from industry sources. The proportion of 
trials with sole industry support varied between journals, from 7% in BMJ to 
32% in NEJM in 2005-2006. Industry-supported trials were more frequently 
cited than trials with other types of support, and omitting them from the 
impact factor calculation decreased journal impact factors. The decrease 
varied considerably between journals, with 1% for BMJ to 15% for NEJM in 
2007. For the two journals disclosing data, income from the sales of reprints 
contributed to 3% and 41% of the total income for BMJ and The Lancet in 
2005-2006.
Conclusions: Publication of industry-supported trials was associated with an 
increase in journal impact factors. Sales of reprints may provide a substantial 
income. We suggest that journals disclose financial information in the same way 
that they require them from their authors, so that readers can assess the 
potential effect of different types of papers on journals' revenue and impact.

Addresses: [Lundh, Andreas; Barbateskovic, Marija; Hrobjartsson, Asbjorn; 
Gotzsche, Peter C.] Rigshosp, Nord Cochrane Ctr, Copenhagen, Denmark; 
[Lundh, Andreas; Gotzsche, Peter C.] Univ Copenhagen, Fac Hlth Sci, Inst Med 
& Surg, Copenhagen, Denmark

Reprint Address: Lundh, A, Rigshosp, Nord Cochrane Ctr, Copenhagen, 
Denmark.

E-mail Address: al at cochrane.dk
ISSN: 1549-1277
DOI: 10.1371/journal.pmed.1000354
URL: 
http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000354