“…The overall assessment scores for the quality of the 39 studies included in the present review are presented in Table 1. Only one study [28] was judged as having low risk of bias while eighteen [13,22,27,31,36,38,40,41,43,45,46,49,50,52,54,55,67,68] were considered as having moderate risk of bias. Fifteen studies [19, 21, 24-26, 29, 30, 32, 34, 39, 42, 44, 48, 51, 66] were categorized as having serious risk of bias, whereas five studies [20,23,35,37,40] were judged as having critical risk of bias.…”