Study Random
sequence
generation 		Allocation
concealment 		Blinding
(participants
and personnel) 		Blinding
(outcome
assessment) 		Incomplete
outcome
data 		Selective
reporting 		Other
bias
Benic et al. [14] + + + + + + +
Bienz et al. [15] + + ? - + + +
Hassouna et al. [16] + + + + + + +
Ioannidis et al. [17] + + - + + + +
Koller et al. [18] + + ? + + + +
Müller et al. [19] + + + ? + + +
Osman et al. [20] + - - ? + + +
Payer et al. [21] + + + + + + +
Siddiqi et al. [22] + + + + + + +
Tolentino et al. [23] + ? - + + + +

+ = yes; - = no; ? = unclear.