2. Quality Assessment: A = adequate; B = unclear; C = inadequate; D = not possible.

Study ID	Allocate concealment	Generate allocate	Participants blinded	Providers blinded	Differences in care	Protocol deviations	Analysis deviations	Assessors blinded	Select report result
Bogataj 1995	C	C	D	D	C	A	C	C	C
Burridge 1997	C	C	D	D	C	A	A	C	A
Cauraugh 2000	B	B	C	D	A	A	A	B	C
Cauraugh 2002	B	B	C	D	A	A	A	C	A
Cauraugh 2003	A	A	C	D	A	A	A	B	A
Chae 1998	C	C	A	D	A	C	C	A	A
Cozean 1988	B	B	A	A	A	A	A	A	C
Daly unpublished	B	B	D	D	A	A	C	B	A
Francisco 1998	B	A	C	D	A	A	A	A	A
Gosman‐Hedstrom 1998	A	A	D	D	A	A	A	A	A
Heckman 1997	B	C	C	D	A	A	A	B	C
Johansson 2001	A	A	D	D	A	A	A	A	C
Kimberley 2004	B	B	A	A	A	A	A	A	A
King 1996	B	B	C	D	B	A	A	B	A
Linn 1999	B	B	C	D	A	A	A	A	A
Macdonell 1994	B	B	D	D	A	B	B	A	A
Merletti 1978	B	B	D	D	A	B	B	B	C
Pei 2001	B	B	D	D	C	A	B	B	B
Popovic 2003	B	C	C	C	A	A	A	A	A
Powell 1999	A	A	C	C	A	A	C	A	C
Sonde 1998	B	B	C	C	A	B	B	B	C
Tekelou 1998	B	B	A	C	A	A	B	B	A
Wright unpublished	B	B	D	D	A	A	A	B	A
Yan 2005	A	B	A	D	A	A	C	A	C