Grading the quality of evidence in clinical practice guidelines

From The Embassy of Good Science

Grading the quality of evidence in clinical practice guidelines

What is this about?

Clinical practice guidelines (CPGs) are designed to support the decision-making processes in patient care. A large number of guidelines are available both from medical associations and national health departments. The content of a CPG is based on a systematic review of clinical evidence - the main source for evidence-based care. Guidelines report the quality of the evidence used when they formulate the recommendations. For each recommendation in the guidelines, the level of evidence and strength of the recommendation are defined[1]. The quality of evidence has been defined as “reflecting the extent to which confidence in the estimate of an effect is adequate to support recommendations”[2]. The grading of the recommendations may vary across professional health agencies and scientific societies.

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group have developed the GRADE system, which is intended as a common, sensible and transparent approach to grading the quality of evidence for the use in clinical guidelines[3]. The GRADE approach has a wide dissemination, with endorsement from more than 50 organizations worldwide, including WHO and Cochrane.


[1] Cura Della Redazione A. La costruzione delle linee guida [Clinical practice guidelines: what they are  and how are developed]. Assist Inferm Ric. 2014;33:214-8.


[2] Guyatt GH, Oxman AD, Vist GE, Kunz R, Falck‐Ytter Y, Schünemann HJ, et al. GRADE: what is “quality of evidence” and why is it important to clinicians? BMJ. 2008;336:995–8.


[3] The GRADE working group [Internet]. GRADE [accessed 8 September, 2020]. Available online at: http://www.gradeworkinggroup.org 2013.


Why is this important?

When clinicians apply or offer the treatment to their patients, they should be up to date with the most recent guidelines regarding the particular treatment. The recommendation in the guideline may arise from a well- conducted and large randomised controlled trial. In that case, clinician can provide the treatment while being aware of all the benefits and the risks. On the other hand, treatment recommendations may come from studies that are graded as evidence of lower quality. If so, the treatment should be applied bearing in mind possible undesirable effects or costs, so clinicians can help patients to decide according to their values and preferences. Since the recommendations in the guidelines affect patients' lives, guidelines and recommendations must therefore transparently indicate whether the evidence is one of high quality or there is an uncertain balance.

For whom is this important?

What are the best practices?

Experts in their respective fields and organizations who are in charge of creating clinical practice guidelines should be aware of discrepancies that may arise if the grading system is not well defined. Ratings of quality of evidence should be transparent and based on detailed and clear criteria, so it can be used by clinicians and patients. However, it can't be expected of clinicians or patients to comprehend a variety of grading systems. A simple, transparent grading of the recommendation, such as the GRADE system, is an example of a good solution. It's the system that provides their users to assess the judgments behind recommendations regarding health care.

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