Study finds meta-analysis conclusions biased by drug company funding

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Previously, like here, here and here, I have highlighted the way that the pharmaceutical industry appears to use its financial muscle to ensure its products end up in a favourable result. Earlier this month, the British Medical Journal published another study on this theme. The particular focus of this review were studies known as ‘meta-analyses’ ” studies which lump together a number of similar pieces of research in an effort to get an overall view of a treatment’s effectiveness.

The researchers who undertook this review looked at a total of 124 meta-analyses concerning drug treatment for high blood pressure (hypertension). They then compared the results of those meta-analyses that had a financial link with one pharmaceutical company with those that did not (and were, presumably, independently funded).

They looked at the relationship between funding and the results of the meta-analyses. They found that having a link with a drug company did not mean that a meta-analysis was more likely to report favourable results. That’s nice to know.

However, the researchers went further by then assessing the relationship between funding and the conclusions drawn by the authors of the meta-analysis. And this is where things got more interesting: Meta-analyses that had drug company funding were 4-5 times more likely to report positive findings compared to those that had been independently funded (same results, remember).

What this demonstrates is just how subjective supposedly ‘objective’ researchers can be with regard to their opinions, and just how corruptible these opinions are when vested interest is at play.

Another issue highlighted by this review is the process of ‘peer review’ ” where academics vet studies for suitable methodology and appropriateness for publication. Basically, one job of reviewers is to detect and screen out studies which show discordance between the results they show and the conclusions drawn by the authors of the study. However, it seems that some reviewers are failing with regard to this.

The authors of the BMJ review write: Both editors and peer reviewers must have read manuscript versions of those meta-analyses containing discordant results and conclusions, yet they did not prevent publication of biased conclusions. Editors and peer reviewers, as well as policymakers, meta-analysts, and readers should closely scrutinise the conclusions of meta-analyses to ensure that they are supported by the data.�


1. Yank V, et al. Financial ties and concordance between results and conclusions in meta-analyses: retrospective cohort study. BMJ doi:10.1136/bmj.39376.447211.BE (published 16 November 2007)

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