Table 2.

Summary of Cochrane risk-of-bias tool for randomised trials (version 2).

Study	Randomisation process	Deviations from intended interventions	Missing outcome data	Measurement of outcome	Selection of reported result	Overall bias
Alpay and Turhan (2001)	High	High	Low	High	Some concerns	High
Flores-Ramos et al. (2003)	Some concerns	Low	Low	Low	High	High
Freeman et al. (1999)	Some concerns	Low	Low	Low	Some concerns	Some concerns
Freeman et al. (2002)	High	Low	Low	Some concerns	Some concerns	High
Freeman et al. (2004)	Low	Low	Low	Low	Some concerns	Some concerns
Landén et al. (2007)	Low	Low	Low	Low	Some concerns	Some concerns
Wikander et al. (1998)	Low	Low	Low	Low	Some concerns	Some concerns
Wu et al. (2008)	High	Low	Low	Low	Some concerns	High