TABLE 2.

Grades of Recommendation

Grades of Recommendation		Strength of Evidence	Level of Obligation
A	Strong evidence	A preponderance of level I and/or level II studies support the recommendation. This must include at least 1 level I study	Should
B	Moderate evidence	A single high-quality randomized controlled trial or a preponderance of only level II studies support the recommendation. This included studies with short-term follow-up (eg, 3 months or less) and smaller sample sizes (eg, fewer than 100 participants)	May
C	Weak evidence	A single level II study supports the recommendation	Can
D	Conflicting or no evidence	Level I and/or level II studies disagree with respect to their conclusions or provide no evidence of benefit	Should not