Table 3. Risk of bias in studies.

Study ID	Random sequence generation	Allocation concealment	Blinding of participants	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other sources of bias
Scahill, 2001	U	U	L	U	U	U	L
Cummings, 2002	U	L	L	U	U	U	L
Goetz,1987	U	U	U	U	L	U	U
Leckman,1991	U	U	U	U	H	U	L
Du,2008	L	U	L	L	U	U	L
Singer,1994	U	U	U	U	L	U	U
Zhong,2007	L	U	U	L	U	U	L
Niederhofer,2003	U	U	U	L	U	U	U
Hedderick, 2009	U	U	L	L	L	U	L
Kurlan,1991	U	U	U	U	U	U	U
Smith-hicks,2007	L	U	U	U	L	U	U
Jankovic, 2010	L	U	U	U	L	U	U
Scahill,1997	U	U	L	U	L	U	L
George,1993	U	U	U	L	L	U	U
Spencer,2002	U	L	U	U	U	U	L
Feigin, 1995	L	U	U	U	U	U	L
Shapiro, 1989	U	U	U	U	L	L	U
Sallee, 1997	U	L	U	U	L	U	U
Shapirc,1984	U	U	U	U	L	L	U
Sallee, 1999	U	U	U	U	U	H	U
Scahill, 2003	L	L	U	U	L	U	U
Dion, 2002	U	U	U	U	L	L	U
Gaffney,2002	U	U	U	U	L	L	U
Gilbert,2004	L	L	L	L	L	L	U
Yoo,2013	U	U	U	U	L	U	L
Ghanizadeh,2014	L	U	L	L	L	U	L
Eggers,1988	U	U	U	U	U	U	L
Onofrj, 2000	L	U	U	U	L	L	U
Muller-vahl,2002	U	L	L	L	L	U	U
Gadow,1995	U	U	U	U	U	U	L
Gadow,1999	U	U	U	U	U	U	L
Gadow,2007	U	L	U	U	U	U	L
Castellanos,1997	U	U	U	U	U	U	L
Kurlan,2002	L	L	L	U	L	U	L
Silver, 2001	U	U	U	U	U	U	L
Gilbert, 2003	U	U	L	U	H	U	U
Gilbert, 2000	L	L	L	U	L	U	L
Kurlan,2012	U	U	U	U	H	U	L
Goetz,1994	U	U	U	L	U	U	U
Singer, 2001	L	U	L	U	U	U	H
Lemmon,2015	L	U	L	U	U	U	U
Bloch,2016	U	L	L	L	U	U	U
Allen,2005	L	U	U	U	L	U	L
Spencer,2008	U	U	U	U	H	U	L
Silver,2001	L	L	L	U	H	U	L
Mcconville,1992	U	U	U	U	L	U	L
Zhao,2010	U	L	L	L	L	L	U
Zheng,2016	U	U	L	U	L	L	L
Li, 2009	L	U	U	U	L	L	U
Wu,2010	U	U	U	U	U	U	U
Wu,2009	L	U	U	U	U	L	U
Toran,2005	U	U	U	U	U	U	H
Nicolson,2005	U	U	U	U	L	U	L

Note: H: high risk; L:low risk; U:unclear