eTable 1. GRADE evaluation of the confidence in the effect estimates (modified from Balshem et al. [e78] and Meerpohl et al. [e79]).

Confidence in the effect estimates	Symbolic representation				Interpretation/implications
High					We are very confident that the true effect is close to the estimate of effect.
Moderate					We are reasonably confident in the estimate of effect: the true effect is probably close to the estimate of effect; however, there is a possibility that it is substantially different.
Low					We have limited confidence in the estimate of effect: the true effect may be substantially differ from the estimate of effect.
Very low					We have very little confidence in the estimate of effect: the true effect is likely to be substantially different from the estimate of effect.

GRADE, Grading of Recommendations Assessment, Development and Evaluation