2.6. Document quality evaluation

The bias risk assessment tool in Cochrane5.1.0 is used to evaluate the methodological quality of the included trials. The corresponding risk degree is judged by the 2 researchers from the aspects of Randomsequencegeneration, Allocationconcealment, Blindingofparticipantsandpersonnel, Blindingofoutcomeassessment, Incompleteoutcome Data, Selectivereporting and Otherbias, and the assessment results are cross-checked. If disputes are discussed with each other, if no agreement can be reached, it will be agreed with the third researcher. Finally, RevMan5.3 software is used to evaluate the bias risk of the study.