“…Six studies were conducted in European countries [ 12 , 19 , 20 , 22 , 23 , 28 ], six in North American countries [ 17 , 21 , 25 , 26 , 29 , 30 ], and four in Asian countries [ 8 , 24 , 27 , 31 ]. Three studies were prospective cohort study [ 21 , 23 , 25 ], seven were retrospective cohort study [ 8 , 17 , 20 , 24 , 26 , 27 , 29 ], two were case-control study [ 12 , 31 ], two were cross-sectional study [ 19 , 30 ], one was case series [ 28 ], and one was retrospective observational study [ 22 ]. Of the 16 studies analyzed, ten were comparative and analyzed using the 24-point scale; the remaining six non-comparative studies were analyzed on the 16-point scale.…”