“…Most of the studies involved randomization [ 23 , 29 , 31 , 35 - 38 , 46 - 48 , 51 , 53 ], with four exceptions [ 21 , 28 , 43 , 5 ]. Most also involved allocation concealment, again with four exceptions [ 28 , 45 , 46 , 51 ]. Blinding of the participants was done in more than half of the studies the exceptions being [ 21 , 28 , 31 , 35 , 45 - 46 , 51 ], while there was no clear blinding of the outcome in more than half the exceptions being [ 23 , 29 , 36 - 38 , 47 ].…”