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. 2021 Jan 21;8:6. doi: 10.1186/s40779-020-00295-z

Table 1.

Grading of recommendations

Grade of recommendation Clarity of risk/benefit Quality of supporting evidence Implication
1A: Strong recommendation, high-quality evidence Benefits clearly outweigh the risks and burdens, or vice versa 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 Benefits clearly outweigh the risks and burdens, or vice versa 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 Benefits clearly outweigh the risks and burdens, or vice versa Observational studies or case series Strong recommendation but subject to change when higher quality evidence becomes available
2A: Weak recommendation, high-quality evidence Benefits closely balanced with the risks and burden RCTs without important limitations or overwhelming evidence from observational studies Weak recommendation, best action may differ depending on the patient, treatment circumstances, or social values
2B: Weak recommendation, moderate-quality evidence Benefits closely balanced with the risks and burden RCTs with important limitations (inconsistent results, methodological flaws, indirect or imprecise) or exceptionally strong evidence from observational studies Weak recommendation, best action may differ depending on the patient, treatment circumstances, or social values
2C: Weak recommendation, low-quality or very low-quality evidence Uncertainty in the estimates of the benefits, risks, and burden; benefits, risk, and burden may be closely balanced Observational studies or case series Very weak recommendation; alternative treatments may be equally reasonable and merit consideration