Table 2.

Appraisal of the four reviewed studies using the Cochrane risk of bias tool

	Hopman-Rock & Westhoff (2000) [16]	van Baar et al. (2001) [19]	Rosemann et al. (2007) [18]	Hansson et al. (2010) [17]
Sequence generation	?	+	+	?
Allocation concealment	?	+	+	+
Blinding	?	?	?	?
Incomplete outcome data	?	+	?	+
Selective outcome reporting	?	?	?	+
Other sources of bias	?	?	?	?

Key (Low risk of bias = +, High risk = −, Unclear of risk = ?)