Table 1. Risk of bias and applicability assessment grading of 31 studies as per the PROBAST criteria.

Research	Participant bias	Predictor bias	Outcome bias	Analysis bias	Overall bias rating	Overall applicability rating
Delen, 2005 [2]	Low	Low	Low	High	High	Low
Bellaachia, 2006 [23]	Low	Low	Low	Low	Low	Low
Endo, 2007 [24]	Low	Low	Low	Moderate	Moderate	Low
Khan, 2008 [25]	Low	Low	Low	High	High	Low
Thongkam, 2008 [26]	Low	Low	Low	Moderate	Moderate	Low
Choi, 2009 [27]	Low	Low	Low	High	High	Low
Liu, 2009 [28]	Low	Low	Low	High	High	Low
Wang, 2013 [29]	Low	Low	Low	Moderate	Moderate	Low
Kim, 2013 [30]	Low	Low	Low	Moderate	Moderate	Low
Park, 2013 [31]	Low	Low	Low	Moderate	Moderate	Low
Shin, 2014 [32]	Low	Low	Low	Moderate	Moderate	Low
Wang, 2015 [33]	Low	Low	Low	Moderate	Moderate	Low
Wang, 2014 [34]	Low	Low	Low	Moderate	Moderate	Low
Chao, 2014 [35]	Low	Low	Low	Moderate	Moderate	Low
García-Laencina, 2015 [36]	Low	Low	Low	Low	Low	Low
Lotfnezhad Afshar, 2015 [37]	Low	Low	Low	Low	Low	Low
Khalkhali, 2016 [38]	Low	Low	Low	Low	Low	Low
Shawky, 2016 [39]	Low	Low	Low	Moderate	Moderate	Low
Sun, 2018 [40]	Low	Low	Low	Low	Low	Low
Sun, 2018 [41]	Low	Low	Low	Moderate	Moderate	Low
Zhao, 2018 [42]	Low	Low	Low	Moderate	Moderate	Low
Fu, 2018 [43]	Low	Low	High	High	High	High
Lu, 2019 [44]	Low	Low	Low	High	High	Low
Abdikenov, 2019 [45]	Low	Low	Low	Moderate	Moderate	Low
Kalafi, 2019 [46]	Low	Low	Low	High	High	Low
Shouket, 2019 [47]	Low	Low	Low	Moderate	Moderate	Low
Ganggayah, 2019 [48]	Low	Low	Low	High	High	Low
Simsek, 2020 [49]	Low	Low	Low	Moderate	Moderate	Low
Salehi, 2020 [50]	Low	Low	Low	High	High	Low
Tang, 2020 [51]	Low	Moderate	Low	Moderate	Moderate	Moderate
Hussain, 2020 [52]	Low	Low	Low	Moderate	Moderate	Low