Table 2.

NOS scale quality assessment

Author (Year)	Selection	Comparability	Outcomes	Quality score
Verter (2021) [12]	★★★	★★★	★★★	8
Wang (2019) [24]	★★★	★★★	★★★	8
Kim (2019) [3]	★★★	★★★	★★★	7
Neal (2015) [25]	★★★	★★★	★★★	8
Neal (2011) [26]	★★★	★★★	★★★	7
Neal (2009) [27]	★★★	★★★	★★★	7
Mao (2019) [28]	★★★	★★★	★★★	8
Halazun (2008) [29]	★★★	★★★	★★★	8
Erstad (2020) [30]	★★★	★★★	★★★	7
Neofytou (2014) [31]	★★★	★★★	★★★	7
Peng (2017) [32]	★★★	★★★	★★★	7
Zeman (2013) [33]	★★★	★★★	★★★	8
Giakoustidis (2015) [34]	★★★	★★★	★★★	7
Wu (2016) [35]	★★★	★★★	★★★	7
Hamada (2020) [21]	★★★	★★★	★★★	7
Zhang (2012) [36]	★★★	★★★	★★★	7
Weiner (2018) [37]	★★★	★★★	★★★	7
Tohme (2015) [38]	★★★	★★★	★★★	7

★: 1 point