Table 2.

Criteria for recommendation (grades)

Grade A	Action is strongly recommended In principle at least one Level I item of evidence indicating effectiveness is present
Grade B	Action is recommended In principle at least one Level II item of evidence indicating effectiveness is present
Grade C1	Action may be considered, but scientific grounds are not yet sufficient (Alternatively, scientific grounds are not yet sufficient, but the possibility exists that effectiveness can be expected) Multiple Level III items of evidence indicating effectiveness are present, and results are generally consistent
Grade C2	Scientific grounds are not sufficient and application in routine treatment is not recommended
Grade D	Action is not recommended Usefulness/effectiveness is not evident, and indeed the treatment may be harmful

In addition to the question of evidence, recommendation Grade A can be applied based on judgment on the level of general common sense. Because evidence is extremely sparse in the case of rare diseases, recommendation grades are decided based on the judgment of the Drafting Committee