Grades of recommendation
GRADE system

1A
Strong recommendation. High quality evidence.
Clarity of risk/benefit
Benefits clearly outweigh risk and burdens, or vice versa.
Quality of supporting evidence
Consistent evidence from well performed randomised, controlled trials or overwhelming evidence of some other form. Further research is unlikely to change our confidence in the estimate of benefit and risk.
Implications
Strong recommendation, can apply to most patients in most circumstances without reservation.
1B
Strong recommendation. Moderate quality evidence.
Clarity of risk/benefit
Benefits clearly outweigh risk and burdens, or vice versa.
Quality of supporting evidence
Evidence from randomised, controlled trials with important limitations (inconsistent results, methodological flaws, indirect or imprecise), or very strong evidence of some other form. Further research (if performed) is likely to have an impact on our confidence in the estimate of benefit and risk and may change the estimate.
Implications
Strong recommendation, likely to apply to most patients
1C
Strong recommendation. Low quality evidence.
Clarity of risk/benefit
Benefits appear to outweigh risk and burdens, or vice versa.
Quality of supporting evidence
Evidence from observational studies, unsystematic clinical experience, or from randomised, controlled trials with serious flaws. Any estimate of effect is uncertain.
Implications
Relatively strong recommendation; might change when higher quality evidence becomes available.
2A
Weak recommendation. High quality evidence.
Clarity of risk/benefit
Benefits closely balanced with risks and burdens.
Quality of supporting evidence
Consistent evidence from well performed, randomised, controlled trials or overwhelming evidence of some other form. Further research is unlikely to change our confidence in the estimate of benefit and risk.
Implications
Weak recommendation, best action may differ depending on circumstances or patients or societal values.
2B
Weak recommendation. Moderate quality evidence.
Clarity of risk/benefit
Benefits closely balanced with risks and burdens, some uncertainty in the estimates of benefits, risks and burdens.
Quality of supporting evidence
Evidence from randomised, controlled trials with important limitations (inconsistent results, methodological flaws, indirect or imprecise), or very strong evidence of some other form. Further research (if performed) is likely to have an impact on our confidence in the estimate of benefit and risk and may change the estimate.
Implications
Weak recommendation, alternative approaches likely to be better for some patients under some circumstances.
2C
Weak recommendation. Low quality evidence.
Clarity of risk/benefit
Uncertainty in the estimates of benefits, risks and burdens; benefits may be closely balanced with risks and burdens.
Quality of supporting evidence
Evidence from observational studies, unsystematic clinical experience, or from randomised, controlled trials with serious flaws. Any estimate of effect is uncertain.
Implications
Very weak recommendation; other alternatives may be equally reasonable.