In this short interview, our PhD student Camilla Hansen Nejstgaard, who is also based at the Centre for Evidence-Based Medicine Odense (CEBMO) at the University of Southern Denmark tells us about how conflicts of interest may impact on recommendations of drugs and medical devices. She is the lead author of a recently published Cochrane Methodology review on this topic.
What does this Cochrane review tell us about the impact of conflicts of interests in clinical guidelines, advisory committee reports, opinion pieces, and narrative reviews?
The findings from our review indicate that financial conflicts of interest are associated with favourable recommendations in clinical guidelines, advisory committee reports, opinion pieces, and narrative reviews. As an example, this means that guidelines written by authors with financial conflicts of interest, more often have recommendations that are favourable towards a new drug treatment than guidelines written by authors without conflicts of interest. We included 21 studies in our review and conducted four separate analyses on each of the four types of documents. These analyses provided similar findings but had some statistical uncertainty around the size of the effect.
We also investigated the impact of non-financial conflicts of interest. Such interest can occur, for example, when radiologists are authors of clinical guidelines on mammography screening (this is what we call specialty interests). However, we only found a single study investigating the impact from specialty interest in clinical guidelines and the results were uncertain, but indicated a similar direction of effect.
Our findings are in line with previous Cochrane Reviews on conflicts of interest in primary research and systematic reviews. However, the results of our current review have less statistical precision and more research is needed, particularly on the impact of non-financial conflicts of interest.
What can guideline issuing organisations learn from this evidence?
Our findings suggest that authors of clinical guidelines may interpret evidence differently depending on whether or not they have financial conflicts of interest. Some guideline issuing organisations such as the National Institute for Health and Care Excellence, the US Preventive Services Task Force, and the World Health Organization have already implemented policies aimed at minimizing the potential impact from conflicts of interest. For example, by minimizing the number and role of guideline authors with financial conflicts of interest. Even though our review did not investigate the impact from such conflicts of interest policies, our findings support the practice of minimising conflicts of interest.
What should patients, doctors and healthcare decision makers take from this evidence?
Based on our findings, we suggest that patients, doctors, and healthcare decision makers primarily use clinical guidelines, opinion pieces, and narrative reviews that have been written by authors without financial conflicts of interest. If that is not possible, users should read and interpret the publications with caution. Furthermore, our findings suggest that if committee members, for example at a regulatory drug agency, are asked to vote on the recommendation of a drug approval, they may be more likely to vote in favour of approving the drug when they have financial conflicts of interest.
Why is this review important?
Recommendations in clinical guidelines, opinion pieces, and narrative reviews as well as decisions about which interventions are approved by advisory committees have substantial impact on the interventions offered to patients. It is therefore essential that such recommendations are evidence-based and as little influenced by conflicts of interest as possible. If not, we may end up wasting resources on treatments that do not actually work, or even harming patients.
The Cochrane review was also co-published in the BMJ. See the BMJ version here.