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

RCT, Randomized controlled trial.
Adapted from Guyatt et al. Used with permission.