Table 2. Risk of bias.

	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data addressed	Selective outcome reporting	Other bias	Decision
Barlow et al., [28]	Low	Low	High	High	Low	Low	Low	Low risk
Bombardier et al., [29]	Low	Low	High	High	Low	Low	High	Moderate risk
Ehde et al.,[30]	Low	Low	Low	Low	Low	High	High	Low risk
Ennis et al.,[31]	Low	Unsure	High	High	Low	Low	Low	Low to moderate risk
Finlayson et al., [32]	Low	Low	Low	High	Low	Unclear	High	Low to moderate risk
Graziano et al., [33]	Low	Unsure	Low	High	Low	Low	High	Low to moderate risk
Khan et al., [35]	Low	Unsure	High	High	Low	Low	Low	Low to moderate risk
Miller et al., [36]	Low	Low	High	High	High	Low	Low	Moderate risk
Moss-Morris et al., [37]	Low	Low	High	Unsure	Low	Low	High	Low to moderate risk
O’Hara et al., [34]	Low	Low	High	High	High	Low	Low	Moderate risk