Table 3.

Risk of bias of the included randomized controlled trials.

Study	Randomization process	Deviations from intended interventions	Missing outcome data	Measurement of the outcome	Selection of the reported result	Overall bias
Dong et al., 2020 [36]	Low	Low	Low	Low	Some concerns	Low
Li et al., 2020 [37]	Low	Low	Low	Low	Some concerns	Low
Zhang et al., 2020 [38]	Low	Low	Low	Low	Some concerns	Low
Deng et al., 2019 [39]	Low	Low	Low	Some concerns	Some concerns	Some concerns
Dang et al., 2018 [40]	Low	Low	Low	Some concerns	Some concerns	Some concerns
Zhang et al., 2017 [41]	Low	Low	High	Low	Some concerns	High
Zhou and Gao, 2017 [42]	Low	Low	Low	Low	Some concerns	Some concerns
Chai, 2016 [43]	Low	Low	Low	Low	Some concerns	Some concerns
Chen et al., 2016 [44]	Low	Low	Low	Low	Some concerns	Some concerns
Geng et al., 2016 [45]	Some concerns	Low	Low	Low	Some concerns	Some concerns
Zhang et al., 2014 [46]	Some concerns	Low	Low	Low	Some concerns	Some concerns
Zhou et al., 2014 [47]	Low	Low	Low	Some concerns	Some concerns	Some concerns
Cheng et al., 2013 [48]	Some concerns	Low	Low	Low	Some concerns	Low
Qian, 2013 [49]	Low	Low	Low	Low	Some concerns	Low
Wang, 2013 [50]	Some concerns	Low	Low	High	Some concerns	High
Liu et al., 2012 [52]	Some concerns	Low	Low	Low	Some concerns	Low
Li et al., 2012 [51]	Some concerns	Low	Low	Some concerns	Some concerns	Some concerns
Ma and Zhang, 2012 [53]	Some concerns	Low	Low	Low	Some concerns	Some concerns
Luo, 2010 [54]	Some concerns	Low	High	Some concerns	Some concerns	High
Gao and Zhao, 2009 [55]	Some concerns	Low	Low	Some concerns	Some concerns	Some concerns
Kappa	0.688	1	0.688	1	1	1