Table 1.

Explanation of definitions of grading of recommendations assessment development and evaluation (GRADE) score used by the GRADE method.

GRADE	Explanation	Definition strength of recommendation	Definition quality of evidence
1A	Strong recommendation High quality of evidence	Benefits clearly outweigh risks and burdens, or vice versa	Further research is very unlikely to change our confidence in the estimate of effect
1B	Strong recommendation Moderate quality of evidence	Benefits clearly outweigh risks and burdens, or vice versa	Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
1C	Strong recommendation Low quality of evidence	Benefits clearly outweigh risks and burdens, or vice versa	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
1D	Strong recommendation Very low quality of evidence	Benefits clearly outweigh risks and burdens, or vice versa	Any estimate of effect is very uncertain
2A	Weak recommendation High quality of evidence	Trade-offs between benefits and risks and burdens are closely balanced	Further research is very unlikely to change our confidence in the estimate of effect
2B	Weak recommendation Moderate quality of evidence	Trade-offs between benefits and risks and burdens are closely balanced	Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
2C	Weak recommendation Low quality of evidence	Trade-offs between benefits and risks and burdens are closely balanced	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
2D	Weak recommendation Very low quality of evidence	Trade-offs between benefits and risks and burdens are closely balanced	Any estimate of effect is very uncertain