Evidence-Based Scoring System
This is the first time that the American College of Cardiology/
American Heart Association evidence-based scoring system (see
http://circ.ahajournals.org/manual/manual_IIstep6.shtml) has
been incorporated into the AHA’s endocarditis treatment guidelines. The purpose of the scoring system is to assist the clinician
in interpreting these recommendations and formulating treatment decisions. The system is based on both a classification of
recommendations and the level of evidence. Each treatment
recommendation has been assigned a class and a level of
evidence. The use of this system should support but not supplant
the clinician’s decision making in the management of individual
patients’ cases.
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