Study Year of
publication 		Random
sequence
generation 		Allocation
concealment 		Binding of
participants
and personnel 		Blinding of
outcome
assessments 		Incomplete
outcome
data 		Selective
reporting 		Other
bias
Wu et al. [27] 2012 ? ? ? ? ? - -
Shehata et al. [28] 2013 - - - ? - - ?
Zúñiga et al. [29] 2013 ? + - ? ? - ?
Zhang et al. [30] 2014 - - - ? - - ?

+ = low risk; ? = unclear risk; - = high risk.