Table 2.

Categories of quality (certainty) of evidence (adapted from GRADE [16])

High	Very confident that the true effect lies close to that of the estimate of the effect
Moderate	Moderate confidence 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	Limited confidence in the effect estimate – the true effect may be substantially different from the estimate of the effect
Very low	Very little confidence in the effect estimate – the true effect is likely to be substantially different from the estimate of effect