Grading of recommendations

Grade	Recommendation
A (Evidence-level quality Ia, Ib)	Requires at least 1 randomized controlled trial as part of the body of literature of overall good, and consistency addressing the specific recommendation
B (Evidence levels IIa, IIb, III)	Requires availability of well-conducted clinical studies but no randomized clinical trials on the topic of recommendation
C (Evidence level IV)	Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities; indicates absence of directly applicable studies of good quality