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Grades of recommendation assigned according to the level of the evidence and its applicability to a target population [6].
| Grade | Level of the Evidence |
|---|---|
| Grade A | Level 1 evidence that is directly applicable to the target population |
| Grade B | Extrapolated level 1 evidence, or directly applicable level 2 evidence |
| Grade C | Extrapolated level 2 evidence or directly applicable level 3 or 4 evidence |
| Grade D | All other evidence from case reports and expert opinion |
