Most meta-analyses of pharmaceutical treatments published in major medical journals fail to include information on financial conflicts of interest in the original trials, even when the trials were funded by the pharmaceutical industry or include authors employed by drug manufacturers, a study published March 9 in JAMA showed.
The omission of those data from meta-analyses represents "a major gap in the reporting of conflicts of interest, and suggest[s] that, without a formal reporting policy, [conflicts of interest] from [randomized, controlled trials] are unlikely to be reported when results are synthesized in meta-analyses," reported Michelle Roseman of the department of psychiatry at McGill University, Montreal, and her colleagues.
The authors recommended that the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines, which most researchers follow when reporting data for meta-analyses, be updated to require authors of meta-analyses to report funding sources of included randomized controlled trials.
Authors of meta-analyses also should include information on trials' funding sources and authors' financial ties to industry when evaluating the risk of trial bias, the study authors recommended.
The researchers investigated whether meta-analyses of pharmacological treatments published in "high-impact" biomedical journals included information on the conflicts of interest reported in the original studies. They selected 29 meta-analyses of patented pharmacological treatments, all of which were published in major medical journals in 2009. The journals included JAMA, the Lancet, Annals of Internal Medicine, and BMJ.
The 29 meta-analyses reviewed included 509 randomized clinical trials. Of those, only two meta-analyses, or 7%, reported randomized, controlled trial funding sources, and none reported author-industry ties or employment by the pharmaceutical industry, the investigators found (JAMA 2011;305:1008-17).
However, when the study authors evaluated the individual randomized controlled trials included in the meta-analyses, they found that more than 62% included information on the trial's funding source. Of those, nearly 69% were funded in part or entirely by the pharmaceutical industry, about 30% were funded by nonindustry sources, and fewer than 1% reported that the trial received no funding.
Only about 26% of the randomized, controlled trials included in the 29 meta-analyses reported author financial disclosures, according to the study. Of those, nearly 69% reported one or more authors having financial ties to the pharmaceutical industry. Almost all of the randomized, controlled trials included in the 29 meta-analyses examined in the JAMA study – 95% – reported author affiliations, and more than 26% of the trials included at least one author employed by the pharmaceutical industry.
Of the two meta-analyses that reported funding sources of the included randomized, controlled trials, one listed funding sources in a table footnote, and the other in the "Characteristics of Studies" table that followed the main document and references, according to the researchers. "Neither mentioned [randomized, controlled trial] funding sources in the column of a core table, in the text, or in an assessment of potential bias," they noted.
None of the 29 meta-analyses analyzed reported author-industry financial ties or employment associated with the included clinical trials.
The study's authors said that "consumers of research, including patients and physicians," want to see disclosures of researchers' financial ties to industry.
"Authors of meta-analyses are expected to transparently assess and interpret potential sources of bias from included studies that could influence outcomes," the authors wrote. "Meta-analysis authors should document that they have evaluated all potentially relevant sources of bias, whether or not a particular source of possible bias is present in the studies reviewed and whether or not the magnitude of bias is expected to be large in comparison with other likely sources of bias."
Author Dr. Joel Lexchin reported being a consultant to a law firm representing Apotex in 2007, the Canadian federal government in a lawsuit challenging the Canadian ban on direct-to-consumer advertising of prescription drugs in 2007-2008, and a law firm representing a plaintiff in a case against Allergan in 2010. The other authors reported no disclosures.