Random
sequence
generation 		Allocation
concealment		 Blinding of
outcome
assessment		 Incomplete
outcome
data		 Selective
reporting		 Timing of
outcome
assessments		 Other
sources of
bias
Baeshen et al. [5] ? ? + + + + +
Huang et al. [8] ? ? + + + + +
Enaia et al. [19] ? ? ? + + + +
Agarwal et al. [20] ? ? + + + + +
Akin et al. [27] ? ? ? + + + +
Du et al. [28] ? ? ? + + + +
Bailey et al. [29] ? + + + + + ?
Richter et al. [30] + ? ? + + ? +
Al Mulla et al. [31] ? ? ? + + + +
Robertson et al. [32] ? + + + + + +
Bröchner et al. [33] + + ? + + + ?
Beerens et al. [34] ? + + + + + ?