Table 2.

The risk of bias of included Randomized Controlled Trials.

Study	Random sequence generation (selection bias)	Allocation concealment (selection bias)	Blinding of participants and personnel (performance bias)	Blinding of outcome assessment (detection bias)	Incomplete outcome data (attrition bias)	Selective reporting (reporting bias)	Other bias
Fu XX [12]	L	U	U	U	U	U	U
Zhou WM [23]	L	U	U	U	U	U	U
Ding XJ [24]	L	U	U	U	U	U	U
Duan C [25]	L	L	L	H	U	U	U

H: High risk, L: Low risk, U: Unclear risk