The American Heart Association Evidence-Based Scoring System

 

 

Classification of Recommendations

Class I: Conditions for which there is evidence, general

agreement, or both that a given procedure or treatment is

useful and effective.

Class II: Conditions for which there is conflicting evidence,

a divergence of opinion, or both about the usefulness/

efficacy of a procedure or treatment.

Class IIa: Weight of evidence/opinion is in favor of

usefulness/efficacy.

Class IIb: Usefulness/efficacy is less well established by

evidence/opinion.

Class III: Conditions for which there is evidence, general

agreement, or both that the procedure/treatment is not useful/

effective and in some cases may be harmful.

 

Level of Evidence

Level of Evidence A: Data derived from multiple randomized

clinical trials

Level of Evidence B: Data derived from a single randomized

trial or nonrandomized studies

Level of Evidence C: Consensus opinion of experts

 

Circulation 2006 114: 1761 1791.