Table 1.

Grading of recommendations according to the GRADE system

Grade	Strength of recommendation	Benefit vs. risk	Quality of studies	Implication
1A	Strong (high-quality evidence)	Benefits clearly outweigh risks and burdens or vice versa	RCTs without important limitations or overwhelming evidence from observational studies	Strong recommendation; can apply to most patients in most circumstances without reservation
1B	Strong (moderate-quality evidence)	Benefits clearly outweigh risks and burdens or vice versa	RCTs with important limitations or exceptionally strong evidence from observational studies	Strong recommendation; can apply to most patients in most circumstances without reservation
1C	Strong (low- or very low-quality evidence)	Benefits clearly outweigh risks and burdens or vice versa	Observational studies or case series	Strong recommendation but may change when higher quality evidence becomes available
2A	Weak (high-quality evidence)	Benefits closely balanced with risks and burdens	RCTs without important limitations or overwhelming evidence from observational studies	Weak recommendation; best action may differ depending on circumstances or patients’ or societal values
2B	Weak (moderate-quality evidence)	Benefits closely balanced with risks and burdens	RCTs with important limitations or exceptionally strong evidence from observational studies	Weak recommendation; best action may differ depending on circumstances or patients’ or societal values
2C	Weak (low- or very low-quality evidence)	Uncertainty in the estimates of benefits, risks, and burdens; benefits, risks, and burdens may be closely balanced	Observational studies or case series	Very weak recommendation; other alternatives may be equally reasonable

GRADE, Grading of Recommendations, Assessment, Development, and Evaluations; RCT, randomized controlled trial.