GRADE Working Group grades of evidence High-certainty: Further research is very unlikely to change our confidence in the estimate of effect. Moderate-certainty: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low-certainty: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low-certainty: We are very uncertain about the estimate.