Table 3.

Levels of evidence

Level of evidence	ILATF	BTS	IAB	JICS
High Evidence	GRADE A: requires at least one randomized control trial as part of a body of literature of overall good quality and consistency addressing the specific recommendation	GRADE A/B | 1 +  + and 1 +	“Level 1: High‐quality evidence supported by findings from well‐executed randomized controlled trials or unequivocal evidence from well‐conducted observational studies with strong effects”	"Level 1: High‐quality evidence supported by findings from well‐executed randomized controlled trials or unequivocal evidence from well‐conducted observational studies with strong effects "
Moderate Evidence	Grade B: requires availability of well-conducted clinical studies but no randomized clinical trials on the topic of the recommendation	GRADE C/D | 1-/2 + /2 +  +	Level 2: Moderate‐quality evidence from randomized trials or from several observational studies with some limitations (inconsistency, indirectness, flaws in conduct, reporting bias, imprecise estimates, small sample size, or others)	Level 2: Moderate‐quality evidence from randomized trials or from several observational studies with some limitations (inconsistency, indirectness, flaws in conduct, reporting bias, imprecise estimates, small sample size, or others)
Low Evidence	"Grade C: requires evidence from expert committee reports or opinions and clinical experience of respected authorities."	Important practice point | 3 and 4	"Level 3: Low‐quality evidence from observational studies or from controlled trials with serious limitations UPP: Not supported by sufficient evidence; however, a consensus reached by the working group, based on clinical experience and expertise "	"Level 3: Low‐quality evidence from observational studies or from controlled trials with serious limitations UPP: Not supported by sufficient evidence; however, a consensus reached by the working group, based on clinical experience and expertise "