Andreas Lundh and colleagues investigated the effect of publication of large industry-supported trials on citations and journal income, through reprint sales, in six general medical journals
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.
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.
Please see later in the article for the Editors' Summary
Medical journals publish many different types of papers that inform doctors about the latest research advances and the latest treatments for their patients. They publish articles that describe laboratory-based research into the causes of diseases and the identification of potential new drugs. They publish the results of early clinical trials in which a few patients are given a potential new drug to check its safety. Finally and most importantly, they publish the results of randomized controlled trials (RCTs). RCTs are studies in which large numbers of patients are randomly allocated to different treatments without the patient or the clinician knowing the allocation and the efficacy of the various treatments compared. RCTs are best way of determining whether a new drug is effective and have to be completed before a drug can be marketed. Because RCTs are very expensive, they are often supported by drug companies. That is, drug companies provide grants or drugs for the trial or assist with data analysis and/or article preparation.
Why Was This Study Done?
Whenever a medical journal publishes an article, the article's authors have to declare any conflicts of interest such as financial gain from the paper's publication. Conflict of interest statements help readers assess papers—an author who owns the patent for a drug, for example, might put an unduly positive spin on his/her results. The experts who review papers for journals before publication provide similar conflict of interest statements. But what about the journal editors who ultimately decide which papers get published? The International Committee of Medical Journal Editors (ICMJE), which produces medical publishing guidelines, states that: “Editors who make final decisions about manuscripts must have no personal, professional, or financial involvement in any of the issues that they might judge.” However, the publication of industry-supported RCTs might create “indirect” conflicts of interest for journals by boosting the journal's impact factor (a measure of a journal's importance based on how often its articles are cited) and its income through the sale of reprints to drug companies. In this study, the researchers investigate whether the publication of industry-supported RCTs influences the impact factors and finances of six major medical journals.
What Did the Researchers Do and Find?
The researchers determined which RCTs published in the New England Journal of Medicine (NEJM), the British Medical Journal (BMJ), The Lancet, and three other major medical journals in 1996–1997 and 2005–2006 were supported wholly, partly, or not at all by industry. They then used the online academic citation index Web of Science to calculate an approximate impact factor for each journal for 1998 and 2007 and calculated the effect of the published RCTs on the impact factor. The proportion of RCTs with sole industry support varied between journals. Thus, 32% of the RCTs published in the NEJM during both two-year periods had industry support whereas only 7% of the RCTs published in the BMJ in 2005–2006 had industry support. Industry-supported trials were more frequently cited than RCTs with other types of support and omitting industry-supported RCTs from impact factor calculations decreased all the approximate journal impact factors. For example, omitting all RCTs with industry or mixed support decreased the 2007 BMJ and NEJM impact factors by 1% and 15%, respectively. Finally, the researchers asked each journal's editor about their journal's income from industry sources. For the BMJ and The Lancet, the only journals that provided this information, income from reprint sales was 3% and 41%, respectively, of total income in 2005–2006.
What Do These Findings Mean?
These findings show that the publication of industry-supported RCTs was associated with an increase in the approximate impact factors of these six major medical journals. Because these journals publish numerous RCTs, this result may not be generalizable to other journals. These findings also indicate that income from reprint sales can be a substantial proportion of a journal's total income. Importantly, these findings do not imply that the decisions of editors are affected by the possibility that the publication of an industry-supported trial might improve their journal's impact factor or income. Nevertheless, the researchers suggest, journals should live up to the same principles related to conflicts of interest as those that they require from their authors and should routinely disclose information on the source and amount of income that they receive.
Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1000354.
This study is further discussed in a PLoS Medicine Perspective by Harvey Marcovitch
The International Committee of Medical Journal Editors provides information about the publication of medical research, including conflicts of interest
The World Association of Medical Editors also provides information on conflicts of interest in medical journals
Information about impact factors is provided by Thomson Reuters, a provider of intelligent information for businesses and professionals; Thomson Reuters also runs Web of Science