Table 2 Four levels of evidence to assess the quality of a body of evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach
Quality level* | Definition |
|---|---|
High | We are very confident that the true effect lies close to that of the estimate of the effect |
Moderate | We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different |
Low | Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect |
Very low | We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of the effect |