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Table 3: Classes of recommendation and levels of evidence. |
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Class |
Definition |
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I |
Evidence and/or general agreement that a given treatment or procedure is beneficial, useful, and effective |
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IIa |
Weight of evidence/opinion is in favor of usefulness/efficacy |
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IIb |
Usefulness/efficacy is less well established by evidence/opinion |
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III |
Evidence or general agreement that the treatment or procedure is not useful/effective and in some cases may be harmful |
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Level |
Source of evidence |
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A |
Data derived from multiple randomized clinical trials or meta-analyses |
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B |
Data derived from a single randomized clinical trial or large non-randomized studies |
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C |
Consensus of expert opinion and/or small studies, retrospective studies, registries |
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Classification of recommendations and levels of evidence adapted from the European Society of Cardiology (ESC) Guidelines.6,7,16 |
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