Table 2.

Risk of Methodological Bias of the Included Studies.

Study	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data addressed	Selective reporting	Other bias
Beith et al 29	L	L	L	L	L	L	H
Hu and Zhao 31	L	H	H	U	L	H	H
Ji et al 38	L	L	L	L	L	L	L
Li 36	L	L	L	L	H	L	H
Lu et al 34	L	L	H	U	L	L	H
Liu 35	L	L	H	U	L	H	H
Meng and Lü 30	L	L	H	U	L	L	H
Shi 37	L	L	H	H	H	L	L
Xie et al 33	L	H	H	L	L	H	H
Zhu et al 32	L	H	H	U	L	L	H

Abbreviations: L, low risk; H, high risk; U, unclear risk of bias.