“…A total of 12 studies 27 , 29 , 30 , 31 , 32 , 38 , 40 , 41 , 42 , 44 , 46 , 47 were considered to have a low risk of bias, and 12 studies 28 , 33 , 34 , 35 , 36 , 37 , 39 , 43 , 45 , 48 , 49 , 50 were considered to have a moderate risk of bias ( appendix 10 p 17 ). Specifically, 15 studies 29 , 30 , 31 , 32 , 34 , 35 , 38 , 40 , 41 , 42 , 44 , 46 , 47 , 48 , 50 reported a random component in the sequence generation process.…”