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Table 2 GRADE Quality of evidence and strength of recommendations

From: Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines

Quality of evidence and strength of recommendation Clarity of balance between desirable and undesirable effects Methodological quality of supporting evidence Implications
High-quality evidence, strong recommendation Desirable effects clearly outweigh undesirable effects or vice versa Consistent evidence from well-performed RCTs or exceptionally strong evidence from unbiased observational studies Recommendation can apply to most patients in most circumstances. Further research is unlikely to change our confidence in the estimate effect
Moderate quality evidence, strong recommendation Desirable effects clearly outweigh undesirable effects or vice versa Evidence from RCTs with important limitations (inconsistent results, methodological flaws, indirectness, imprecision) or exceptionally strong evidence from unbiased observational studies Recommendation can apply to most patients in most circumstances. Further research (if performed) is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
Low-quality evidence, strong recommendation Desirable effects clearly outweigh undesirable effects or vice versa Evidence for at least one critical outcome from observational studies, RCTs with serious flaws or indirect evidence Recommendation may change when higher quality evidence becomes available. Further research (if performed) is likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate
Very low-quality evidence, strong recommendation (rarely applicable) Desirable effects clearly outweigh undesirable effects or vice versa Evidence for at least one critical outcome from unsystematic clinical observations or very indirect evidence Recommendation may change when higher quality evidence becomes available; any estimate of effect for at least one critical outcome is very uncertain
High-quality evidence, weak recommendation Desirable effects closely balanced with undesirable effects Consistent evidence from well-performed RCTs or exceptionally strong evidence from unbiased observational studies The best action may differ depending on circumstances or patients or societal values. Further research is unlikely to change our confidence in the estimate effect
Moderate quality evidence, weak recommendation Desirable effects closely balanced with undesirable effects Evidence from RCTs with important limitations (inconsistent results, methodological flaws, indirectness, imprecision) or exceptionally strong evidence from unbiased observational studies Alternative approaches likely to be better for some patients under some circumstances. Further research (if performed) is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
Low-quality evidence, weak recommendation Uncertainty in the estimates of desirable effects, harms, and burden; desirable effects, harms, and burden may be closely balanced Evidence for at least one critical outcome from observational studies, RCTs with serious flaws or indirect evidence Other alternatives may be equally reasonable. Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate
Very low-quality evidence, weak recommendation Major uncertainty in the estimates of desirable effects, harms, and burden; desirable effects may or may not be balanced with undesirable effects Evidence for at least one critical outcome from unsystematic clinical observations or very indirect evidence Other alternatives may be equally reasonable. Any estimate of effect, for at least one critical outcome, is very uncertain