Table 1 Definitions for strength of recommendations

Rating of RecommendationTranslation of evidence to recommendations
A: Established as useful/predictive or not useful/predictive for the given condition in the specified populationLevel A rating requires at least one convincing Class I study or at least two consistent, convincing Class II studies
B: Probably useful/predictive or not useful/predictive for the given condition in the specified populationLevel B rating requires at least one convincing Class II study or at least three consistent Class III studies
C: Possibly useful/predictive or not useful/predictive for the given condition in the specified populationLevel C rating requires at least two convincing and consistent Class III studies
U: Data inadequate or conflicting. Given current knowledge, test/predictor is unproven