Level of evidence
| Level | Definition |
|---|---|
| High | Evidence from a well-conducted RCT/meta-analysis with low risk of bias in study design and conduct, or from an observational study with no bias in study design or conduct and an effect size rated as very large |
| Moderate | Evidence derived from RCT or meta-analysis with bias in study design and conduct, or from an observational study without bias in study design or conduct and a large effect size |
| Low | Evidence resulting from RCT or meta-analysis with biases reported in two or more aspects of study design and conduct, or from an observational study without biases in study design and conduct |
| Very low | Evidence from observational studies, case reports, or inadequately conducted observational studies with biases in study design and conduct |
RCT = randomized controlled trial.