2.5 The certainty of evidence
Two independent reviewers (XKL and YJY) independently used the GRADE approach for network meta-analysis to assess the certainty of the evidence.15-17 Each outcome had four classifications: high, moderate, low, or very low, based on consideration of the risk of bias, incoherence, inconsistency, indirectness, intransitivity, publication bias, and imprecision. Discrepancies were resolved by discussion with a third reviewer (NS) if necessary.