Recommendation Ratings Scheme - Clinical Guidelines Program

Recommendation Ratings Scheme
Strength		Quality of Evidence
Rating	Definition	Rating	Definition
A	Strong	1	Based on published results of at least 1 randomized clinical trial with clinical outcomes or validated laboratory endpoints.
B	Moderate	*	Based on either a self-evident conclusion; conclusive, published, in vitro data; or well-established practice that cannot be tested because ethics would preclude a clinical trial.
C	Optional	2	Based on published results of at least 1 well-designed, nonrandomized clinical trial or observational cohort study with long-term clinical outcomes.
		2†	Extrapolated from published results of well-designed studies (including nonrandomized clinical trials) conducted in populations other than those specifically addressed by a recommendation. The source(s) of the extrapolated evidence and the rationale for the extrapolation are provided in the guideline text. One example would be results of studies conducted predominantly in a subpopulation (e.g., one gender) that the committee determines to be generalizable to the population under consideration in the guideline.
		3	Based on committee expert opinion, with rationale provided in the guideline text.