TABLE 2. Grades of Recommendations^a.

GRADE	RECOMMENDATION	STRENGTH OF RECOMMENDATION
A	Strong evidence	A preponderance of level I and/or level II studies supports the recommendation. This must include at least 1 level I study
B	Moderate evidence	A single high-quality randomized controlled trial or a preponderance of level II evidence supports the recommendation
C	Weak evidence	A single level II study or a preponderance of level III and IV studies supports the recommendation
D	Expert opinion	Best practice based on the clinical experience of the guideline development team and guided by the evidence, which may be conflicting. Where higher quality studies disagree with respect to their conclusions, it may be possible to come to agreement on certain aspects of intervention (eg, variations in treatment/diagnostic test, population, or setting that may account for conflict)

^aEach Action Statement is preceded by a bolded letter grade (A-D) indicating the strength of the recommendation.