“…In all included studies, the sampling strategy was relevant to address the research question. In more than two thirds of the studies, the study sample was clearly described and representative of the target population [ 13 , 20 , 23 , 24 , 25 , 26 , 28 , 30 , 31 , 32 , 33 , 34 , 35 , 37 , 38 , 39 , 40 , 42 , 43 , 45 , 47 , 48 , 49 , 50 ], the risk of non-response bias low [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 30 , 31 , 33 , 35 , 36 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 48 , 49 ], and the statistical analysis appropriate to answer the research question [ 13 , 20 , 22 , 24 , 25 , 27 ,…”