Table 2.

Risk of bias assessment.

Studies	Random sequence generation	Allocation concealment	Selective reporting	Other sources of bias	Blinding (participants and personnel)	Blinding (outcome assessment)	Incomplete outcome data	General risk of bias
Medina et al. (42)	L	H	H	H	U	H	L	Bad
RISerus et al. (43)	L	H	H	L	L	U	H	Bad
Albers et al. (44)	L	L	H	L	L	U	L	Good
Riserus et al. (45)	L	H	H	H	L	U	H	Bad
Desroches et al. (46)	L	H	H	H	L	U	L	Bad
Gaullier et al. (47)	L	H	L	L	L	U	L	Good
Song et al. (48)	L	H	L	L	L	U	L	Good
Smedman et al. (49)	L	H	H	L	H	H	L	Bad
Ramakers et al. (50)	L	L	H	L	L	L	L	Good
Colakoglu et al. (11)	L	H	H	H	L	U	H	Bad
Taylor et al. (51)	L	H	H	L	L	U	L	Fair
Naumann et al. (52)	L	H	H	H	H	H	H	Bad
Gaullier et al. (27)	L	L	L	H	L	U	H	Fair
Nazare et al. (53)	L	H	L	L	L	U	L	Good
Iwata et al. (55)	L	H	H	H	L	U	L	Bad
Watras et al. (54)	L	H	H	H	L	U	L	Bad
Mullen et al. (57)	L	H	H	H	L	U	L	Bad
Steck et al. (56)	L	H	H	L	L	U	L	Fair
Kim et al. (58)	L	H	H	H	H	H	L	Bad
Sneddon et al. (28)	L	H	H	L	L	U	L	Fair
Turpeinen et al. (59)	L	H	H	H	L	U	H	Bad
Aryaeian et al. (60)	L	H	H	H	L	U	H	Bad
Raff et al. (61)	L	H	H	H	L	U	H	Bad
Zhao et al. (62)	L	H	H	H	L	U	L	Bad
Norris et al. (63)	L	L	H	L	L	U	L	Good
MacRedmond et al. (12)	L	H	H	H	H	H	L	Bad
Tavakkoli Darestani et al. (66)	L	L	H	H	L	U	L	Fair
Sofi et al. (64)	L	L	H	L	L	U	L	Good
Sluijs et al. (65)	L	L	H	L	L	U	L	Good
Joseph et al. (68)	L	H	L	H	L	U	H	Bad
Brown et al. (67)	L	H	H	H	L	U	H	Bad
Pfeuffer et al. (69)	L	H	H	L	H	H	H	Bad
Rubin et al. (70)	L	L	H	H	L	U	L	Fair
Shadman et al. (71)	L	H	L	L	L	U	L	Good
Lopez-Plaza et al. (16)	L	L	H	H	L	U	L	Fair
Bulut et al. (72)	L	L	H	L	L	U	L	Good
Eftekhari et al. (73)	L	H	H	H	L	U	L	Bad
Aryaeian et al. (19)	L	H	H	H	L	U	L	Bad
Baghi et al. (74)	L	H	L	L	L	U	L	Good
Dus-Zuchowska et al. (75)	L	L	H	H	L	U	L	Fair
Abedi et al. (76)	L	L	L	L	H	H	L	Fair
Aslani et al. (18)	L	L	H	H	L	U	H	Bad

U, unclear risk of bias; L, low risk of bias; H, high risk of bias.

Good < 2 high risks of bias; Fair = 2 high risks of bias; Bad > 2 high risks of bias.