Table 1.

Comparison of Levels of Evidence and Classes of Recommendation Criteria in Practice Guidelines in 2008 and 2016

Criterion	2008a	2016b
Class of recommendation
	Class I	Class 1 (STRONG)
	Class IIa	Class IIa (MODERATE)
	Class IIb	Class IIb (WEAK)
	Class III	Class III: no benefit (MODERATE)
		Class III: harm (STRONG)
Level of evidence
	Level A	Level A
	Level B	Level B‐R
		Level B‐NR
	Level C	Level C‐LD
		Level C‐EO

EO indicates expert opinion; LD, limited data; NR, nonrandomized; R, randomized.

^aCriterion from3 Note that in the Methodology Manual and Policies From the ACC/AHA Task Force on Practice Guidelines (2010),4 the Class III class of recommendation was split into “no benefit” and “harm” subcategories.

^bCriterion from5