Table 2.

Quality evaluation of the included studies.

Included studies	Random allocation	Allocation concealment	Double blind method	Evaluation of blindness	Data integrity	Selective report	others
Chen 2006	Unknown	No	No	No	Yes	Yes	Yes
He 2002	No	No	No	No	Yes	Yes	Yes
Hu 2005	Unknown	No	No	No	Yes	Yes	Yes
Li 2007	Yes	No	No	No	Yes	Yes	Yes
Liu 2015	Unknown	No	No	No	Yes	Yes	Yes
Wang 2017	Yes	No	No	No	Yes	Yes	Yes
Wu 2014	Yes	No	No	No	Yes	Yes	Yes
Zhang 2015	Unknown	No	No	No	Yes	Yes	Yes