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.