Tuesday, March 9, 2021

Expert Evidence: A Framework for Using GRADE When "No" Evidence Exists

To guide the formulation of clinical recommendations, GRADE relies on the use of direct or, if necessary, indirect evidence from peer-reviewed publications as well as the gray literature. However, in some cases, no such evidence may be found even after an extensive search has been conducted. A new paper - part of the informal GRADE Notes series in the Journal of Clinical Epidemiology - relays the results of piloting an "expert evidence" approach and provides key suggestions when using it.

As opposed to simply asking the panel members of a guideline to base their recommendations off of informal opinion, the expert evidence approach systematizes this process by eliciting the extent of their experience with certain clinical scenarios through quantitative survey methods. In this example, at least 50% of the panel members were free of conflicts of interest, with various countries and specialties represented. While members were not required to base their answers off of patient charts, the authors suggest that this can be used to further increase the rigor of the survey. 



As a result of the survey, the recommendations put forward reflected a cumulative 12,000 cases of experience. Because the members felt that at least some recommendation was necessary to help guide care - where the alternative would be to provide no recommendation at all - the guideline helped to fill a gap while indicating the current lack of high-quality published evidence for several clinical questions, which may help guide the production of higher-quality evidence and recommendations in the future. Importantly, by utilizing a survey approach to facilitate the formulation of recommendations, the authors note that it avoided the pitfall of "consensus-based" approaches to guideline development which can often manifest as simply reflecting the opinions of those with the loudest voices. 

Mustafa RA, Cuello Garcia CA, Bhatt M, Riva JJ, Vesely S, Wiercioch W, ... & HJ Sch√ľnemann. (2021). How to use GRADE when there is "no" evidence? A case study of the expert evidence approach. J Clin Epidemiol, in-press. 

Manuscript available from the publisher's website here