Table 1.

Grading criteria for clinical evidence of the treatments.

Grade	Evidence levels quality/Type of evidence	Requirements
High	Ia Evidence obtained from meta-analysis of randomized controlled trials Ib Evidence obtained from at least one randomized controlled trial	Requires at least one randomized controlled trial as part of the body of literature of overall good consistency addressing the specific recommendation.
Medium	IIa Evidence obtained from at least one well-designed controlled study without randomization IIb Evidence obtained from at least one other type of well-designed quasi-experimental study III Evidence obtained from well-designed non-experimental descriptive studies, such as comparative studies, correlation studies, and case-control studies	Requires availability of well-conducted clinical studies with no randomization clinical trials on the topic of recommendation
Low	IV Evidence obtained from expert committee reports or opinions and/or clinical experience of respected authorities	Requires evidence from expert committee reports or opinions and/or clinical experience of respected authorities. Indicates the absence of directly applicable studies of good quality

Adapted from General Guidelines for Methodologies on Research and Evaluation of Traditional Medicine World Health Organization (WHO, 2000).