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Description of the common levels of evidence used in clinical practice guidelines
| Level of evidence | Description |
|---|---|
| Level A | Data derived from multiple randomized clinical trials or meta-analyses Multiple populations evaluated |
| Level | B Data derived from a single randomized clinical trial or large non-randomized studies Limited populations evaluated |
| Level C | Consensus of the experts and/or small studies, retrospective studies, and registries Very limited populations evaluated |
