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July 19, 2019

Evidence vs Consensus in Clinical Practice Guidelines

Author Affiliations
  • 1City of Hope, Duarte, California
  • 2McMaster University, Hamilton, Ontario, Canada
JAMA. 2019;322(8):725-726. doi:10.1001/jama.2019.9751

Clinical practice guidelines have become increasingly prominent in clinical medicine over the last 4 decades, and represent one of the most important tools for potentially improving clinical decision-making and, in turn, potentially improving patients’ outcomes.1

Historically, many organizations categorized their guidelines as evidence-based or consensus-based and some organizations, including some of the largest professional organizations devoted to developing clinical practice guidelines for the management of heart disease (the American College of Cardiology and the American Heart Association) and the largest organization devoted to cancer (the American Society of Clinical Oncology), continue to make this distinction.

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4 Comments for this article
How and Why Is "Evidence" Generated?
Kevin Kelly, MD | Weill Cornell Medicine
Another caution about the ideology of "evidence-based medicine" concerns the fact that in most cases the evidence is not generated in a scientifically-neutral fashion. Even if we grant that investigators who have a financial interest in the outcome of research will nevertheless conduct the research honestly and publish the results no matter what they show, there remains the issue of which questions are chosen for research. In most cases, this decision is made on the basis of anticipated profits to the sponsoring company, rather than on the basis of anticipated benefit to the public. In a simple example, a drug which is available as a generic might be just as good (or better) for a new indication than a newer drug which is on patent; no one is likely to do the research to demonstrate the effectiveness of the generic, but the sponsor will be willing to invest in research to demonstrate the effectiveness of the patented drug. In this case, a clinician who feels bound to practice "evidence-based medicine" will have to prescribe the more expensive drug, even if there is good reason to believe that the generic would do just as well.
Consensus Creates Ownership, Eases Implementation
Akhil Sangal, MD, MBA dip AMT | Indian Confederation for Healthcare Accreditation: CEO & Director
While evidence is derived from multiple sources and varying credibility, there are multiple views. There is also the changing evidence over a period of time, sometimes contrasting (e.g. cholesterol).

There are thus multiple views with arguments for and against. Building consensus on the other hand has distinct advantages, viz. greater scrutiny of the evidence available generating more varied experiences; however, the greatest advantage is in terms of implementation due to the created ownership through the consensus building process.

We are all aware of the plethora of guidelines being available and the poor rate of implementation of even
most evidence based guidelines. Consensus building is the way forward in this conundrum.
Judicious Consideration: Not Necesssarily Consensus
Barbara Hansen, PhD | University of South Florida, Morsani College of Medicine, Internal Medicine
This thoughtful commentary correctly identifies consensus based on opinions (some of which may be based on low-quality evidence and disparate or conflicting or even indeterminate evidence) vs consensus based on the preponderance of the evidence (especially viewed as high-quality evidence). The authors further note the relevant considerations for patients in the balance of benefit vs tradeoffs, especially those where patient preferences may best be the driving factors. Perhaps in our consensus statements, such as, for example, the 5 yr issuance of "dietary guidelines" or the thresholds for blood pressure therapeutic interventions, we should be less concerned with driving consensus than with thoughtful critique and clear identification of the issues so that application in the clinical setting will best fit both the patient and the situation and will bracket the range of well-reasoned options.
Do What I Say, Do Not Do What I Do?
Joseph Watine, PharmD | Hôpital de Villefranche-de-Rouergue
One of the excellent points with the GRADE approach is that recommendations can be strong, or conditional. Guideline panels following the GRADE approach will make strong recommendations when the benefits of an intervention clearly outweigh the harms and burdens and therefore all, or almost all, fully informed patients would make the same choice. Panels will make discretionary recommendations when the benefits and harms are more closely balanced, and the majority would choose the recommended course of action but a minority would not [1].

The problem is that leading members of the GRADE group themselves may apparently have problems with
their own definitions. For example the European Commision has recently developed Breast Cancer Guidelines under the supervision of such leading members [1]. One of their recommendations is that "for asymptomatic women aged 50 to 69 with an average risk of breast cancer, mammography screening is recommended in the context of an organised screening programme (strong recommendation, mode-rate certainty in the evidence)" [2]. The authors of this recommendation also report "possibly important uncertainty about or variability in how much people value the main outcomes" [2]. Therefore, if the GRADE system (as summarized in the first paragraph above) had actually been used, this recommendation should have been conditional, not strong [3].

Should we trust a method that is not implemented in real life by those who promote this method ?

[1] Djulbegovic B, Guyatt G. Evidence vs Consensus in Clinical Practice
Guidelines. JAMA. 2019 Jul 19. doi: 10.1001/jama.2019.9751.
[2] Schünemann HJ, Lerda D, Dimitrova N, Alonso-Coello P, Gräwingholt A, Quinn C, Follmann M, Mansel R, Sardanelli F, Rossi PG, Lebeau A, Nyström L, Broeders M, Ioannidou-Mouzaka L, Duffy SW, Borisch B, Fitzpatrick P, Hofvind S, Castells X,Giordano L, Warman S, Saz-Parkinson Z; European Commission Initiative on Breast Cancer Contributor Group. Methods for Development of the European Commission Initiative on Breast Cancer Guidelines: Recommendations in the Era of Guideline Transparency. Ann Intern Med. 2019 Jul 23. doi: 10.7326/M18-3445.
[3] European Commission. Recommendations from the European Breast Cancer Guidelines. https://ecibc.jrc.ec.europa.eu/recommendations/