1. Risk of bias of each included studya.

Study	Allocation sequence generation	Allocation concealment	Blinding	Inclusionb
Krudsood 2003	Not described	Not described	No	Inadequate
Lefevre 2001	Not described	Not described	No	Adequate
Mayxay 2004	Not described	Adequate	No	Adequate
Mutabingwa 2005	Adequate	Adequate	No	Adequate
Ndayiragije 2004	Not described	Not described	No	Adequate
Piola 2005	Adequate	Adequate	No	Adequate
Stohrer 2004	Not described	Adequate	No	Adequate
Sutherland 2005	Not described	Adequate	Single	Inadequate
Van Vugt 2000	Not described	Adequate	No	Inadequate

^aInclusion of all randomized participants in the analysis; see the 'Methods of the review' for the assessment methods, and the 'Characteristics of included studies' for the methods used in each trial.