“…Of these, the confounders were 80–100% controlled in three studies [ 21 , 36 , 40 ], while in seven studies [ 3 , 32 , 34 , 41 , 43 , 45 , 48 ], no important confounders were observed between the groups. While most of the studies [ 3 , 21 , 30 , 33 , 34 , 37 , 38 , 39 , 41 , 42 , 44 , 46 , 47 , 48 , 49 ] did not report the outcome assessors’ blinding, six of the studies [ 31 , 35 , 36 , 40 , 43 , 45 ] reported that the outcome assessors were not aware, and only one study [ 32 ] reported that the outcome assessors were aware of the intervention or exposure status of the participants. Data collection methods were shown to be valid in seven studies [ 30 , 32 , 33 , 39 , 40 , 44 , 45 ] and of these, only three studies [ 30 , 40 , 44 ] reported that the data collection methods demonstrated good reliability in that particular data.…”