Meta-analyses of randomised controlled trials seldom show conflict of interest, funding information

Information concerning funding and author conflicts of interest disclosed in the original reports of randomised controlled trials is rarely disclosed when these data are combined in meta-analyses, according to an article in the March 9 issue of JAMA.

'Conflicts of interest (COIs) related to the funding of biomedical research by pharmaceutical companies and financial relationships between researchers and pharmaceutical companies have come under increased scrutiny in recent years. COIs may influence the framing of research questions, study design, data analysis, interpretation of findings, whether to publish results, and what results are reported,' according to background information in the article. 'Compared with nonindustry-funded trials, pharmaceutical industry-funded studies more often yield results or conclusions in support of the sponsor's drug, and authors' relationships with drug manufacturers have been linked to favourable assessments of drug efficacy and safety.'

While guidelines recommend disclosure by authors of study funding sources and also of author-industry financial ties, there are no guidelines for the reporting in meta-analyses of COIs disclosed in included randomised controlled trials (RCTs). 'Meta-analyses are cited more than any other study design and prioritised in grading evidence for practice guidelines,' the authors write. 'Without documentation in meta-analyses of COIs from included RCTs, users of meta-analyses may not have access to important information that could influence their evaluation of the risk of bias in the evidence reported.'

Michelle Roseman, B.A., of McGill University, Montreal, Canada, and colleagues investigated the extent to which pharmaceutical industry funding and author-industry financial ties or author employment disclosed in published reports of RCTs of pharmacological interventions are reported in meta-analyses published in high-impact general and speciality medicine journals and a database of reviews. The researchers selected the 3 most recent meta-analyses of patented pharmacological treatments published January 2009 through October 2009 in several high-impact general medicine journals; in high-impact journals in each of the 5 speciality medicine areas with the greatest 2008 global therapeutic sales (oncology, cardiology, respiratory medicine, endocrinology, and gastroenterology); and in the Cochrane Database of Systematic Reviews. Investigators extracted data on disclosed study funding, author-industry financial ties, and author employment from each meta-analysis, from RCTs included in each meta-analysis, and on whether meta-analyses reported disclosed COIs of included RCTs.

The researchers found that of 29 meta-analyses reviewed, which included 509 RCTs, only 2 meta-analyses (7 percent) reported RCT funding sources; and 0 reported RCT author-industry ties or employment by the pharmaceutical industry. Of the 509 RCTs, 62.5 percent (318 of 509) reported funding source. Of these, 68.9 percent (219 of 318) were funded in part or whole by the pharmaceutical industry; 30.5 percent by non-industry funding sources, including 28 RCTs in which a study drug was supplied by the pharmaceutical industry; and less than 1 percent reported that the trial received no funding. Author financial disclosures were reported in 25.9 percent (132 of 509) of included RCTs. Among these, 68.9 percent (91 of 132) reported 1 or more authors having financial ties to the pharmaceutical industry.

In 7 of 29 meta-analyses, 100 percent of included RCTs disclosed at least 1 form of COI (pharmaceutical industry funding, author-industry financial ties, or employment) in the original RCT publications. In 4 of these 7 meta-analyses, 100 percent of included RCTs that reported study funding were funded by the pharmaceutical industry. Only 1 of the 7 meta-analyses, however, provided information on study funding of included RCTs, and that was done in a table footnote; and 0 reported RCT author-industry ties or employment.

'There is general agreement on the need for complete and transparent disclosure of COI in biomedical research. The results of the present study highlight a major gap in the reporting of COIs and suggest that, without a formal reporting policy, COIs from RCTs are unlikely to be reported when results are synthesised in meta-analyses. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA; requires meta-analysis authors to report the funding source of a meta-analysis] statement should be updated to require authors of meta-analyses to report funding sources of included RCTs or report that funding sources were not disclosed,' the authors write.

'If COIs from included RCTs are not acknowledged in meta-analyses, 1 of 2 messages may be sent to readers - the first is that the authors of the meta-analysis have not considered COI in included studies, which leaves readers in a position of not knowing how to interpret possible biases that may have arisen because of COI in the original RCTs; and the second possible message is that the meta-analysts have in fact assessed the risk of bias related to COI in the original RCTs, concluded that the COIs did not create any biases, and therefore have chosen not to comment on the COIs. This interpretation may lead readers to trust the conclusions of a meta-analysis when they potentially should not. In either case, without acknowledgment of COI due to industry funding or author-industry financial ties from RCTs included in meta-analyses, readers' understanding and appraisal of the evidence from the meta-analysis may be compromised.'