Certainty assessment
The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system11 were used to assess the certainty (quality) of evidence associated with specific outcomes and in constructing a findings summary table. In the process of evaluating the quality of evidence for RCTs, five downgrade factors, including the study limitations, consistency of effect, imprecision, indirectness, and publication bias, were used to estimate the certainty of the outcomes12. The outcomes were degraded from a high-quality level for each degrading factor, rated as either not serious, serious, or very serious.[27, 28] Depending on the severity, outcomes were considered to degrade one (serious) or two levels (very serious), with the final level of evidence quality considered as either high, moderate, low, or very low.