GRADE-Leitlinien: 9. Heraufstufen der Qualität der Evidenz

The most common reason for rating up the quality of evidence is a large effect. GRADE suggests considering rating up quality of evidence one level when methodologically rigorous observational studies show at least a two-fold reduction or increase in risk, and rating up two levels for at least a five-fold reduction or increase in risk. Systematic review authors and guideline developers may also consider rating up quality of evidence when a dose-response gradient is present, and when all plausible confounders or biases would decrease an apparent treatment effect, or would create a spurious effect when results suggest no effect. Other considerations include the rapidity of the response, the underlying trajectory of the condition and indirect evidence. Key PointsGRADE includes three criteria for rating up quality of evidence particularly applicable to observational studies.Rating up one or even two levels is possible when effects in observational studies are sufficiently large, particularly if they occur over short periods of time.A dose-response gradient, or a conclusion that plausible residual confounding would further support inferences regarding treatment effect, may also raise the quality of the evidence.