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What is GRADE?

The quality of the evidence used in the Decision Boxes is made explicit by the use of the GRADE approach. GRADE (Grading of Recommendations Assessment, Development and Evaluation) is a systematic approach to rate the quality of evidence by applying a grade of High, Moderate, Low or Very Low. The quality of evidence is rated for each outcome across studies (Guyatt et al. 2011).

The following definitions of the quality of the evidence are provided by Guyatt et al. (2008) :

  • High quality : Further research is very unlikely to change our confidence in the estimate of effect.
  • Moderate quality : Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
  • Low quality : Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
  • Very low quality : Any estimate of effect is very uncertain.


Rating is modified downward

Rating is modified upward

Study limitations

Large magnitude of effect

Inconsistency of results

Counfounding factor likely minimizes the effect

Indirectness of evidence

Dose response gradient



Likelihood of publication bias


Why Grade the evidence?

The strength of the recommendations to use an intervention or a test varies depending of the quality of the evidence that is supporting this use. Thus, research evidence of high quality is more likely to lead to strong recommendations for or against an intervention, and allow drawing conclusions on the potential beneficial impact for the patient.

The GRADE approach is used in the Decision boxes so that clinicians and patients have an understanding of the strength of the evidence used to develop each Decision box. This information can help clinical decision-making, by allowing the clinician to better understand the critical elements at play when recommending an intervention or a test.

For some outcomes presented in the Decision boxes, confidence in results is graded LOW or MODERATE. This reflects a lack of high-quality evidence. Many clinical questions still need to be further investigated by researchers.


Guyatt et al. (2008). GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-6.

Guyatt G et al. (2011). GRADE guidelines: 1. Introduction-GRADE evidence profiles and summary of findings tables. J Clin Epidemiol. 2011;64(4):383-94.