Author Random sequence generation Allocation concealment Blinding Incomplete outcome data Selective reporting Other bias
Anner et al. [20] ? ? - + ? +
Costa et al. [21] ? ? ? - ? +
Frisch et al. [22] ? ? ? - ? +
Rinke et al. [23] ? ? ? + ? +
Roccuzzo et al. [24] ? ? + + ? +
Roccuzzo et al. [25] ? ? + + ? +
Roccuzzo et al. [26] ? ? + + ? +

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