Study	Reason for exclusion
Cao 2007	Not a randomised trial
Chen 2000	Duplicate
Chen 2001	Not a randomised trial
Chen 2004	Not a randomised trial
Chen 2008	Not a randomised trial
Cui 2006	Not a randomised trial
Gong 2010	Not a randomised trial
Hu 2006	Not appropriate comparison group
Jiang 2013	Similar method and data as Zhang 2007 but with different author team
Jiao 2003	Not a randomised trial
Jin 2008	Not a randomised trial
Li 2004	Not a randomised trial
Li 2006a	Not a randomised trial
Li 2006b	Not a randomised trial
Li 2006c	Not a randomised trial
Li 2013	Not a randomised trial
Liu 2001a	Not a randomised trial
Liu 2001b	Not a randomised trial
Liu 2002	Not a randomised trial
Pan 2005	Not a randomised trial
Qin 2003	Not a randomised trial
She 2000	Not a randomised trial
Song 2008	Not a randomised trial
Su 2006	Not a randomised trial
Sui 2006	Not a randomised trial
Sun 2002	Not a randomised trial
Sun 2006	Not a randomised trial
Tang 2005	Not a randomised trial
Wang 2001	Not a randomised trial
Wang 2003	Not a randomised trial
Wang 2006a	Not a randomised trial
Wang 2006b	Not a randomised trial
Wang 2007	Not a randomised trial
Wang 2009	Not a randomised trial
Wu 2009	Not a randomised trial
Xia 2003	Not a randomised trial
Xiao 2013	Not a randomised trial
Xie 2003	Not a randomised trial
Xue 2016	Not a randomised trial
Yang 2005	Not a randomised trial
Yu 2002	Not a randomised trial
Zhang 2001b	Not a randomised trial
Zhong 2008	Not a randomised trial
Zhou 2014	Not a randomised trial