TableĀ 1

Grading of evidence and recommendations

Grade of recommendationClarity of risk/benefitQuality of supporting evidence
1A. Strong recommendation. High quality evidenceBenefits clearly outweigh risk and burdens, or vice versaConsistent 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
1B. Strong recommendation. Moderate quality evidenceBenefits clearly outweigh risk and burdens, or vice versaEvidence 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 affect our confidence in the estimate of benefit and risk and may change the estimate
1C. Strong recommendation. Low quality evidenceBenefits appear to outweigh risk and burdens, or vice versaEvidence from observational studies, unsystematic clinical experience, or from randomised controlled trials with serious flaws. Any estimate of effect is uncertain
2A. Weak recommendation. High quality evidenceBenefits closely balanced with risks and burdensConsistent 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
2B. Weak recommendation. Moderate quality evidenceBenefits closely balanced with risks and burdens; some uncertainly about the estimates of benefits, risks and burdensEvidence 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 affect our confidence in the estimate of benefit and risk and may change the estimate
2C. Weak recommendation. Low quality evidenceUncertainty in the estimates of benefits, risks, and burdens; benefits may be closely balanced with risks and burdensEvidence from observational studies, unsystematic clinical experience, or from randomised controlled trials with serious flaws. Any estimate of effect is uncertain