Table 2.

Quality assessment of the prospective and retrospective nonrandomized studies using Newcastle–Ottawa scale

Study (year)	Selection	Comparability	Outcome
Kim et al. (2014)[19]	***	*	***
Manoj et al. (2018)[20]	***	**	***
Shetty et al. (2018)[21]	***	**	***
Yang et al. (2014)[22]	***	*	***
Chen et al. (2016)[23]	***	*	***
Özveri Koyuncu et al. (2019)[24]	***	**	***
Pirpir et al. (2017)[25]	***	**	***
Sohn et al.(2017)[26]	***	*	***

*,**,***is the quality assessment score according to Newcastle-Ottawa Scale