TABLE 2.

Recommendations based on defined grades of evidence^*

Grade	Research Quality	Preponderance of benefit over harm	Balance of benefit and harm
A	Well designed RCT’s	Strong recommendation	Option
B	RCT’s with minor limitations; Overwhelmingly consistent evidence from observational studies	Recommendation	Option
C	Observational studies (case control and cohort design)	Recommendation	Option
D	Expert opinion, Case reports, Reasoning from first principles	Option	No recommendation

^*American Academy of Otolaryngology - Head and Neck Surgery Clinical Practice Guideline Development Manual, Third Edition²⁵.