Table 1. Components used in the grading of the quality of evidence and the strength of recommendations.

Category	Grade	Description
Quality of evidence	A	Evidence from high-quality randomized controlled trial (RCT) or systemic reviews/meta-analyses
	B	Evidence from defective RCT, low-quality systemic reviews/meta-analyses, or high-quality observational studies
	C	Evidence from non-randomized, case-control, or other observational studies
	D	Expert individual opinion
Strength of recommendation	1	Strong recommendation
	2	Weak recommendation
	3	No specific recommendation (insufficient evidence on which to formulate a recommendation)