TableĀ 2

Grading the quality of the evidence (adapted from GRADE Working Group, 2004)34

Strength of evidenceInterpretation
High qualityVery confident in the estimate of the effect, and further research is very unlikely to change our confidence.
Moderate qualityModerately confident in the estimate of the effect, but further research may have an important impact on our confidence and may change the estimate.
Low qualitySomewhat confident in the estimate of the effect, but further research is very likely to have an important impact on our confidence and will likely change the estimate.
Very low qualityVery little confidence in the estimate of the effect as it is very uncertain.