Table 4: NOS Scores.

No.

Author, year, country

Selection (4 stars)

Comparability (2 stars)

Outcome/Exposure

(3 stars)

Total Score (9 stars)

1

Cerri, et al. Italy [15]

3

2

2

7

2

Gariballa & Alessa, UK [14]

3

2

3

8

3

Martone, et al. Italy [4]

4

2

2

8

4

Rossi, et al. Italy [16]

3

2

2

7

5

Vetrano, et al, Italy [17]

3

1

3

7

6

Yang, et al. China [18]

3

2

3

8