1. Quality assessment.

Trial	Allocation sequence generation	Allocation concealment	Blinding	Inclusiona
Amer 1992	Unclear	Unclear	Unclear	Adequate
Amerio 2003	Adequate	Adequate	Investigators	Adequate
Avila‐Romay 1991	Unclear	Unclear	Unclear	Adequate
Bachewar 2009	Adequate	Unclear	None	Inadequate
Biele 2006	Adequate	Unclear	Investigators	Adequate
Brooks 2002	Adequate	Unclear	Investigators	Inadequate
Chouela 1999	Unclear	Unclear	Described as "double blind"; participants blinded	Adequate
Glaziou 1993	Unclear	Unclear	Outcomes assessor	Adequate
Gulati 1978	Unclear	Unclear	Unclear	Adequate
Hansen 1986	Unclear	Unclear	"Single blind", unclear who was blinded	Adequate
Ly 2009	Adequate	Unclear	None	Adequate
Macotela‐Ruiz 1993	Unclear	Unclear	Participant and outcomes assessor	Adequate
Madan 2001	Unclear	Unclear	Outcomes assessor	Inadequate
Maggi 1986	Unclear	Unclear	Unclear	Adequate
Nnoruka 2001	Adequate	Unclear	Unclear	Adequate
Schenone 1986	Unclear	Unclear	Unclear	Adequate
Schultz 1990	Unclear	Adequate	Outcomes assessor	Adequate
Singalavanija 2003	Adequate	Unclear	Unclear	Inadequate
Taplin 1986	Unclear	Adequate	Investigators	Adequate
Taplin 1990	Unclear	Adequate	Investigators	Adequate
Usha 2000	Adequate	Adequate	None	Adequate
Zargari 2006	Unclear	Adequate	Investigators and participants	Adequate

^aInclusion of randomized participants in analysis.