Table 2.

Grading of Recommendations, Assessment, Development and Evaluation (GRADE). RCTs randomized controlled trials

Grade of recommendation	Quality of supporting evidence	Implications
1A Strong recommendation, high-quality evidence	RCTs without important limitations or overwhelming evidence from observational studies	Strong recommendation, applies to most patients in most circumstances without reservation
1B Strong recommendation, moderate-quality evidence	RCTs with important limitations (inconsistent results, methodological flaws, indirect analyses or imprecise conclusions) or exceptionally strong evidence from observational studies	Strong recommendation, applies to most patients in most circumstances without reservation
1C Strong recommendation low-quality or very low-quality evidence	Observational studies or case series	Strong recommendation but subject to change when higher quality evidence becomes available
2A Weak recommendation high-quality evidence	RCTs without important limitations or overwhelming evidence from observational studies	Weak recommendation, the best action may differ depending on the patient, treatment circumstances, or social values
2B Weak recommendation moderate-quality evidence	RCTs with important limitations (inconsistent results, methodological flaws, indirect or imprecise) or exceptionally strong evidence from observational studies	Weak recommendation, the best action may differ depending on the patient, treatment circumstances, or social values
2C Weak recommendation low-quality or very low-quality evidence	Observational studies or case series	Very weak recommendation; alternative treatments may be equally reasonable and merit consideration