Table 2.

Quality evaluation of included literatures.

Included studies	Random allocation	Allocation concealment	Double-blind method	Evaluation of blindness	Data integrity	Selective report	Others
Joy 2017	Low risk	Low risk	Low risk	Low risk	Low risk	Low risk	Unclear
Nelson 2009	Unclear	Unclear	Low risk	Low risk	Low risk	Low risk	Low risk
Athyros 2006	Unclear	Low risk	High risk	Unclear	Unclear	Unclear	Unclear
Alam 2018	Low risk	Unclear	Unclear	Low risk	Unclear	Low risk	Unclear
Samy 2011	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk	Low risk
Smits 2016	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk	Unclear
Peng 2013	Low risk	Low risk	Low risk	Unclear	Low risk	Low risk	Unclear
Xu 2015	Unclear	Unclear	Low risk	Unclear	Low risk	Unclear	Unclear
You 2011	Unclear	Unclear	Unclear	Unclear	Low risk	Unclear	Unclear
Bi 2016	Low risk	Unclear	Unclear	Low risk	Low risk	Low risk	Unclear
Qin 2013	Unclear	Low risk	Unclear	Unclear	Low risk	Unclear	Unclear
Lai 2012	Unclear	Unclear	Unclear	Low risk	Low risk	Low risk	Low risk
Jiang 2018	Unclear	Unclear	Unclear	Unclear	Low risk	Unclear	Unclear
Li 2011	Unclear	Unclear	Unclear	Low risk	Low risk	Unclear	Low risk