Table 4.

GRADE certainty of evidence classifications

Certainty of evidence	Interpretation
High ⊕⊕⊕⊕	We are very confident that the true effect lies close to that of the estimate of the effect.
Moderate ⊕⊕⊕O	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 ⊕⊕OO	Our confidence in the effect estimate is limited; the true effect may be substantially different from the estimate of the effect.
Very Low ⊕OOO	We have very little confidence in the effect estimate; the true effect is likely to be substantially different from the estimate of effect.

Source: Reprinted from Eds: Schünemann HJ, Brożek J, Guyatt, GH, Oxman AD. GRADEhandbook: Handbook for grading the quality of evidence and the strength of recommendations using the GRADE approach. Updated October 2013. Accessed March 2, 2022. https://gdt.gradepro.org/app/handbook/handbook.html#h.9rdbelsnu4iy (135).