| Code | Quality of evidence | Definition |
|---|---|---|
| A | High | We are very confident that the true effect lies close to that of the
estimate of the effect.
|
| B | 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.
|
| C | Low | Our confidence in the effect estimate is limited: The true effect may
be substantially different from the estimate of the effect.
|
| D | Very low | We have very little confidence in the effect estimate: The true effect
is likely to be substantially different from the estimate of effect.
|
Source: GRADE (Grading of Recommendations Assessment, Development and Evaluation) Working Group «http://www.gradeworkinggroup.org»1 (modified by the EBM Guidelines Editorial Team)