2.7. Risk of bias assessment

The risk of bias of RCTs included will be evaluated on the basis of the risk of bias tool described in the Cochrane Handbook for Systematic Reviews of Interventions.^[30] Two investigators will independently evaluate the risk of bias from 6 aspects: random sequence generation, allocation consensus, blinding methods, complete outcome data, selective outcome reporting, and other bias. A research with a high risk of bias in one or more domains will be viewed as high risk of bias. A study with a low risk of bias in all domains will be considered as low risk of bias. If not, a research will be treated as unclear risk of bias.

Furthermore, 2 reviewers will independently use the modified Jadad scale to assess the quality of the RCTs included.^[31] Four domains will be appraised, namely “randomization,” “concealment of allocation,” “double blinding,” “withdrawals and dropouts”. According to the scoring principle, 1 to 3 scores will be viewed as low-quality literature, and 4 to 7 scores as high-quality literature.

Disagreements encountered during this process will be resolved through discussion or by a third senior investigator.