Validity and grading of recommendations
| Category of evidence | Grading of recommendations | ||
|---|---|---|---|
| Meta-analysis of randomised controlled trial | Ia | A | |
| Randomised controlled trial | Ib | ||
| Well-designed controlled study without randomisation | IIa | B | |
| Well-designed quasi-experimental study | IIb | ||
| Non-experimental descriptive study | III | ||
| Expert opinion | IV | C | |