. 2020 Jul 21;12(4):1053–1064. doi: 10.1111/os.12736

TABLE 2.

Quality assessment of non‐randomized controlled trials (Newcastle–Ottawa scale for non‐randomized controlled trials)

Study	Selection	Comparability	Exposure or Outcome	total score
Elhadi (2018) ⁹	★★	★★	★★★	7
Kayali (2006) ¹¹	★★★	★	★★	6
Kim (2020) ¹²	★★	★★	★★	6
Kim (2014) ¹⁴	★★★	★	★★	6
Park (2015) ¹⁵	★★	★★	★★	6
Shen (2012) ¹⁶	★★	★★	★★★	7
Zhou (2019) ¹⁷	★★★	★★	★★★	8