Table 2:

Appraisal of risk of bias of the included studies using the Cochrane risk-of-bias tool ²²

Study	Risk of bias
	Random sequence generation	Allocation concealment	Blinding of patients, personnel	Blinding of outcome assessors	Incomplete outcome data	Selective outcome reporting	Other
Winblad et al. 27 study 1	Unclear	Low	Low	Low	Low	Low	Low
Winblad et al. 27 study 2	Unclear	Low	Low	Low	Low	Low	Low
Özenli et al. 28	Unclear	Unclear	Low	Unclear	Unclear	Unclear	Unclear
Salloway et al. 29	Unclear	Low	Low	Low	Unclear	Unclear	Unclear
Petersen et al. 30	Unclear	Unclear	Unclear	Unclear	Low	Unclear	Low
Doody et al. 31	Low	Low	Low	Low	Low	Unclear	Unclear
Feldman et al. 32	Low	Low	Low	Low	Low	Low	Unclear
Ferris et al. 33	Unclear	Unclear	Low	Unclear	High	Unclear	Unclear