Table 1.

Quality of evidence and strength of recommendations

Grade	Content
Quality of evidence
High (A)	We are very confident that the actual effect lies close to that of the estimate of the effect
Moderate (B)	We are moderately confident of the effect estimate: The actual effect is likely to be close to the evaluation of the effect, but there is a possibility that it is substantially different
Low (C)	Our confidence in the effect estimate is limited: The true effect may be substantially different from the evaluation of the effect
Very low (D)	We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect
Strength of recommendations
Strong (1)	Clearly shows the benefits of intervention outweigh the harms or more harms than benefits
Weak (2)	Uncertain about the benefits and harms or the benefits and harms are tantamount regardless of the quality of evidence