Table 1.

Levels of Evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE)

Level	Definition	Implications
High	Strong confidence that the true effect lies close to that of the effect estimate.	It is unlikely that additional trials will change the confidence in the estimated effect.
Moderate	Moderate confidence in the effect estimate.	Future trials may modify the confidence in the effect estimate, and also can change the estimate.
Low	Limited confidence in the effect estimate.	Future trials are likely to importantly impact our confidence in the effect estimate.
Very Low	Uncertain confidence in the effect estimate.	Any effect estimate is uncertain.

Source: Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group. Handbook for grading the quality of evidence and the strength of recommendations using the GRADE approach. Updated October 2013. Available from: https://gdt.gradepro.org/app/handbook/handbook.html.⁽¹⁹⁾