TABLE 3.

Hierarchization of recommendations

A (Levels of evidence IA, IB)	Requires at least one controlled randomized trial as part of the literature, which is of good general quality, consistent, and discusses the specific recommendation.
B (Levels of evidence IIa, IIb, III)	Demands the availability of well-conducted clinical studies, but there are no randomized clinical trials on the topic.
C (Level of evidence IV)	Demands evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates absence of quality, directly applicable studies.