2.4. Assessment of risk of bias
Two investigators (WJX and HFC) independently read the eligible articles
and assessed their methodological validity using the Cochrane
Collaboration’s tool of Review Manager (RevMan version 5.4, Cochrane
Community, London, England) software for assessing the risk of bias in
randomized-controlled trials (RCTs) and resolved disagreements through
discussion[19]. The tool consists of seven items
describing random sequence generation, allocation concealment, blinding
of participants and personnel, blinding of outcome assessment,
incomplete outcome data, selective reporting, and other biases. A
judgment of high, low, or unclear risk of material bias for each item
were assigned.