CHARACTERISTICS OF STUDIES.

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Birch 1990	Not a randomized or quasi-randomized trial
Birch 2000	Not a randomized or quasi-randomized trial
Birch 2006	Not a randomized or quasi-randomized trial
Buck 2009	Not a randomized or quasi-randomized trial
Dadeya 2001	Method of treatment allocation not reported, though comparison is of interest
Elliott 2013	Not a randomized or quasi-randomized trial; review article, intervention comparison not of interest
Figueira 2006	Not a randomized or quasi-randomized trial
Lam 1993	Not a randomized or quasi-randomized trial
Meyer 1998	Not a randomized or quasi-randomized trial
NCT01791946	Included adult participants only (ages 18 to 60 years old)
Shauly 1994	Not a randomized or quasi-randomized trial
Simonsz 2005	Not a randomized or quasi-randomized trial
Spiegel 1997	Not a randomized or quasi-randomized trial
Spierer 1988	Not a randomized or quasi-randomized trial
Weakley 1997	Not a randomized or quasi-randomized trial
Zak 1982	Not a randomized or quasi-randomized trial

Three studies (Dadeya 2001; Lam 1993; Weakley 1997) included outcome measures that we planned to evaluate for our review, but for two studies (Lam 1993; Weakley 1997) the participants were not randomized and for one study (Dadeya 2001) the method of allocation to treatment groups was not available - either in the articles published or by trying to contact the study investigators.