Table 3.

Degrees of recommendation from Guyatt et al. (1995)

Grade of recommendation	Strength of evidence
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 studies support the recommendation
C Weak evidence	A single level II study or a preponderance of level III and IV studies including statements of consensus by content experts support the recommendation
D Conflicting evidence	Higher-quality studies conducted on this topic arrived at conflicting conclusions. The recommendation is based on these conflicting studies
E Theoretical/foundational evidence	A preponderance of evidence from animal or cadaver studies, from conceptual models/principles, or from basic sciences/bench research support this conclusion
F Expert opinion	Best practice based on the clinical experience of the guidelines development team