Grading of evidence4
| Rank | Explanation | Examples |
|---|---|---|
| High | Further research is very unlikely to change our confidence in the estimate of effect | Randomised trials without serious limitations Well-performed observational studies with very large effects (or other qualifying factors) |
| Moderate | Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate | Randomised trials with serious limitations Well-performed observational studies yielding large effects |
| Low | Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate | Randomised trials with very serious limitations Observational studies without special strengths or important limitations |
| Very low | Any estimate of effect is very uncertain | Randomised trials with very serious limitations and inconsistent results Observational studies with serious limitations Unsystematic clinical observations (eg, case series or case reports) |