Strength of recommendation
| A | Directly based on category 1 evidence |
|---|---|
| B | Directly based on category 2 evidence or extrapolated recommendation from category 1 evidence |
| C | Directly based on category 3 evidence or extrapolated recommendation from category 1 or 2 evidence |
| D | Directly based on category 4 evidence or extrapolated recommendation from category 2 or 3 evidence |