Table 2 Newcastle-Ottawa scores of all included articles (n=16)

Mantziari et al.

2015

4

2

2

8

Hübner et al.

2016

4

2

2

8

Labgaa et al.

2017

4

2

2

8

Kumar et al.

2020

4

0

2

6

Müller et al.

2018

4

2

2

8

Galata et al.

2020

4

2

2

8

Fan et al.

1989

4

2

2

8

Labgaa et al.

2020

4

2

2

8

Liu et al.

2017

4

2

2

8

Ai et al.

2019

4

2

2

8

Giovannini et al.

2006

4

0

2

6

Labgaa et al.

2016

4

2

2

8

Hendifar et al.

2016

4

0

2

6

Ge et al.

2017

4

2

2

8

Wierdak et al.

2018

4

0

2

6

Wang et al.

2018

4

2

2

8