Criteria Qi et al.
[23] 		Khullar et al.
[38] 		Yari et al.
[39] 		Miloro and
Criddle [45]
Generating the randomization sequence + + + ?
Randomization sequence concealment - - + +
Masking of investigators, study personnel, or study participants - + + +
Masking the evaluation or measurement of outcomes + - + +
Incomplete results data + + + -
Selective description of results + - + -

"-" = high risk of bias; "+" = low risk of bias; "?" = unclear risk of bias.