• Sara Wickham

Conflicts of interest and bias in research


One of the concerns that those of us blogging on this website share is the way in which commodification, commercialisation and the push to sell products, pharmaceuticals and technologies can affect women’s experiences and care. This is something that Mavis Kirkham will discuss both on this site and elsewhere. So it was interesting to see that, in August 2019, The Cochrane Collaboration published a systematic review looking at ‘Financial conflicts of interest in systematic reviews: associations with results, conclusions, and methodological quality’.

The need for such a review is clearly summarised by the authors. “Financial conflicts of interest in systematic reviews (e.g. funding by drug or device companies or authors' collaboration with such companies) may impact on how the reviews are conducted and reported.” (Hansen et al 2019).

After searching the literature, the authors found ten studies with a total of 995 systematic reviews of drug studies and 15 systematic reviews of device studies. They determined that two of these studies were at low risk of bias and eight at high risk of bias, primarily because of risk of confounding.

The determination that a study is ‘at high risk of bias’ is interesting in itself. There are a number of reasons why a study might be potentially biased. It may be poorly designed. It may be on a topic which is difficult to research, perhaps for ethical or practical reasons. Or it may have been structured, either accidentally or by design, to favour one or other of the products, protocols or interventions that it was measuring.

Having worked in maternity care research for two and a half decades, I am sad to say that I see an increasing number of studies where the latter appears to be the case. Such studies are not necessarily biased towards the promotion of products and technologies, however. Sometimes, they are clearly biased towards the continuance of ideologies and belief systems which position women as being ‘at risk’ or less than capable of giving birth. In some arenas, we use the term ‘decision-based evidence-making’ to describe how so-called evidence is used to support the existing beliefs or desires of those with a vested interest in as particular product, service or intervention. I say ‘so-called’ because the research tends to be of poor quality, or in some cases conducted under conditions which don’t match those in the real world. Yet low-quality findings are often publicised loudly and uncritically and fast determine the standard of practice, to the detriment of those seeking maternity care.

The Cochrane reviewers focused (quite understandably) on financial conflicts of interest, which are somewhat easier to measure.

They concluded that:

“Systematic reviews with financial conflicts of interest more often have favourable conclusions and tend to have lower methodological quality than systematic reviews without financial conflicts of interest. However, it is uncertain whether financial conflicts of interest are associated with the results of systematic reviews. We suggest that patients, clinicians, developers of clinical guidelines, and planners of further research could primarily use systematic reviews without financial conflicts of interest. If only systematic reviews with financial conflicts of interest are available, we suggest that users read the review conclusions with skepticism, critically appraise the methods applied, and interpret the review results with caution.” (Hansen et al 2019).

Ideally, we need more conversation about other types of bias as well. But for now it is very useful to have this Cochrane review and to be able to show that there really are grounds for our concerns about the use of ‘spin’ when it comes to research findings.

Hansen C, Lundh A, Rasmussen K, Hróbjartsson A. Financial conflicts of interest in systematic reviews: associations with results, conclusions, and methodological quality. Cochrane Database of Systematic Reviews 2019, Issue 8. Art. No.: MR000047. DOI: 10.1002/14651858.MR000047.pub2.


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