Table 5.

Risk of bias

Study	Random sequence generation (selection bias)	Allocation concealment (selection bias)	Blinding participants and personnel (performance bias)	Blinding of outcome assessment (detection bias)	Incomplete outcome data (attrition bias)	Selective reporting (reporting bias)	Other bias
Church et al. (2009) (15)	Unclear	NR	High risk	NR	Low risk	Low risk	High risk
Fujita et al. (2003) (52)	Low risk	NR	High risk	NR	Low risk	Low risk	High risk
Hollowell et al (2009) (55)	Low risk	NR	High risk	NR	High risk	Low risk	High risk
Rangan et al (2011) (56)	Low risk	NR	High risk	NR	High risk	Low risk	High risk
Rosenkilde et al. (2012) (21)	Low risk	NR	High risk	NR	Low risk	Low risk	High risk
Turner et al. (2010) (53)	Unclear	NR	High risk	NR	High risk	Low risk	High risk
VanEtten et al. (1997) (54)	High risk	NR	High risk	NR	Low risk	Low risk	High risk

NR, not reported.