Despite a heightened awareness of the need for transparency of financial relationships in clinical medicine and research, a new review of meta-analyses in JAMA found that among a sample of high-impact publications, very few of the reviews acknowledged industry-backing of the source trials.

According to the review, only two of 29 of the meta-analyses selected from recent editions of influential journals identified industry-backed trials as such, even though nearly two-thirds of the trials with declared funding sources were sponsored by drug companies.

A considerable body of research suggests that industry-backed trials tend to portray the drug more positively, favor the drug over placebo, and downplay side effects more often than in non-industry trials (see the JAMA bibliography). This 2006 BMJ article found industry support tended to lower the rigor of meta-analyses.  It seems, then, a matter of some import to have an understanding of trials’ funding sources, both in their original publication and when they are aggregated in reviews.

Of course, blame for this dearth of financial disclosure doesn’t rest solely with the reviewers of the trials – the lack of standard documentation of industry funding and relationships in trials published in major medical journals is a complex and compound problem. For instance, among the Randomized Control Trials (RCT) included in the 29 meta-analyses, only a quarter included financial disclosures for authors, and only two-thirds listed sources of trial backing. In such a landscape, then, it’s tricky–if not impossible–for a meta-analysis to accurately or completely describe the shape and scope of the funding behind the findings.

The researchers call for a standard policy:

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 synthesized in meta-analyses. The PRISMA 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.
There’s much agreement that transparency of potential COIs is important in clinical care and prescriber settings. But progress toward transparency in the clinic may be diluted, if not undermined, without a more unanimous foundation of disclosure in the medical literature, which serves to set the therapeutic standards and practice guidelines used there.

–Kate Petersen, PostScript blogger