. 2015 Oct 19;77(2):191–200. doi: 10.1590/S1808-86942011000200009

Table 5.

Comparing the recommendations from both academies.

Fife et al., Neurology, 2008¹⁸ American Academy of Neurology (AAN)	Bhattacharyya et al., 2008¹⁹ Otolaryngology - Head and Neck Surgery (AAO-HNS).
Level A: Established as efficient, inefficient or harmful for a given condition on the specified population. (requiring at least two consistent class I studies.) Level B: Probably efficient, inefficient or harmful for the condition in the specified population. (Level B required at least one Class I study or at least two consistent Class II studies). Level C: Possibly efficient, inefficient, or harmful for the condition in the specified population. (Class C classification level required at least one Class II study or at least to Class III consistent studies.) Level U: Inadequate or conflicting data with the current knowledge, treatment would not be approved. · The recommendations could have been positive or negative.	“Strong recommendation”: the benefits were clearly higher than the risks and the quality of support evidence was excellent (class A or B). In some clearly identified circumstances, it could be based in less evidence when possible to obtain high quality proof and the benefits would clearly outweigh the risks. “Recommendation”: the benefits were greater than the risks, but the quality of the evidence was not so strong (class B or C). Could have been made under the same previous conditions (A or B). “Option”: the quality of the existing evidence was suspicious (class D) or well conducted studies (class A, B or C) showed small advantages of one method over the other. “Without recommendations”: there was a lack of pertaining evidence (class D), as a not very clear balance of the risks and benefits.

Fife et al., Neurology, 2008¹⁸
American Academy of Neurology (AAN)

Bhattacharyya et al., 2008¹⁹
Otolaryngology - Head and Neck Surgery (AAO-HNS).

Level A: Established as efficient, inefficient or harmful for a given condition on the specified population. (requiring at least two consistent class I studies.)
Level B: Probably efficient, inefficient or harmful for the condition in the specified population. (Level B required at least one Class I study or at least two consistent Class II studies).
Level C: Possibly efficient, inefficient, or harmful for the condition in the specified population. (Class C classification level required at least one Class II study or at least to Class III consistent studies.)
Level U: Inadequate or conflicting data with the current knowledge, treatment would not be approved.

·
The recommendations could have been positive or negative.

“Strong recommendation”: the benefits were clearly higher than the risks and the quality of support evidence was excellent (class A or B). In some clearly identified circumstances, it could be based in less evidence when possible to obtain high quality proof and the benefits would clearly outweigh the risks.
“Recommendation”: the benefits were greater than the risks, but the quality of the evidence was not so strong (class B or C). Could have been made under the same previous conditions (A or B).
“Option”: the quality of the existing evidence was suspicious (class D) or well conducted studies (class A, B or C) showed small advantages of one method over the other.
“Without recommendations”: there was a lack of pertaining evidence (class D), as a not very clear balance of the risks and benefits.