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.