Grading Evidence


Grade A - The conclusion is supported by good evidence.

The evidence consists of results from studies of strong research design for answering the practice question. The results are both clinically important and consistent with minor exceptions at most. The results are free of any significant doubts about generalizability, bias, and flaws in research design.

Grade B - The conclusion is supported by fair evidence.

The evidence consists of results from studies of strong research design for answering the practice question, but there is some uncertainty attached to the conclusion because of inconsistencies among the results from the studies or because of minor doubts about clinical significance, generalizability and/or risk of bias. Alternatively, the evidence consists solely of results from weaker designs for the question addressed, but the results have been confirmed in separate studies and are consistent, with minor exceptions at most.

Grade C - The conclusion is supported by limited evidence or expert opinion.

The evidence consists of results from studies of strong research design for answering the practice question, but there is substantial uncertainty attached to the conclusion because of inconsistencies among the results from different studies or because of serious doubts about clinical significance, generalizability and/or risk of bias. Alternatively, the evidence consists solely of results from a limited number of studies of weak design for answering the question addressed. Finally, the support for a particular recommendation may consist of a consensus statement of informed, respected authorities or descriptive reports of expert panels.

Grade D - A conclusion is either not possible or extremely limited because evidence is unavailable and/or of poor quality and/or is contradictory.

The evidence consists of results from a single study with major design flaws or from studies with highly inconsistent results and/or results that are not generalizable. Alternatively, evidence may be lacking either from authoritative sources or research involving humans.


Note: The quality of the evidence is a major factor determining the grade; however, consideration is given to factors that influence findings, including consistency, impact, generalizability and applicability. In some cases these factors can supersede the evidence base.

Click here to link to PEN Evidence Grading Checklist


PEN® GRADE Recommendations Terminology and Graphics

Strength of Recommendation

Strong recommendation
Conditional recommendation

Implications of Strong and Conditional Recommendations for Different Users (1):

 

Strong Recommendation

Conditional Recommendation

For patients

Most individuals in this situation would want the recommended course of action and only a small proportion would not.

The majority of individuals in this situation would want the suggested course of action, but many would not.

For clinicians

Most individuals should receive the recommended course of action. Adherence to this recommendation according to the guideline could be used as a quality criterion or performance indicator. Formal decision aids are not likely to be needed to help individuals make decisions consistent with their values and preferences.

Recognize that different choices will be appropriate for different patients, and that you must help each patient arrive at a management decision consistent with her or his values and preferences. Decision aids may well be useful helping individuals making decisions consistent with their values and preferences. Clinicians should expect to spend more time with patients when working towards a decision.

For policy-makers

The recommendation can be adapted as policy in most situations including for the use as performance indicators.

Policy-making will require substantial debates and involvement of many stakeholders. Policies are also more likely to vary between regions. Performance indicators would have to focus on the fact that adequate deliberation about the management options has taken place.

Quality of Evidence Grades (1):

⊕⊕⊕⊕ High quality evidence

We are very confident that the true effect lies close to that of the estimate of the effect.

⊕⊕⊕⊝ Moderate quality evidence

We are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.

⊕⊕⊝⊝ Low quality evidence

Our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect.

⊕⊝⊝⊝ Very Low quality evidence

We have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.

References

  1. Schünemann H, Brożek J, Guyatt G, Oxman A, editors. Handbook for grading the quality of evidence and the strength of recommendations using the GRADE approach; Updated October 2013 [cited 2016 Feb 23]. Available from: http://gdt.guidelinedevelopment.org/central_prod/_design/client/handbook/handbook.html