Table 3 Study population of the included studies.

Meyer, Huston¹⁸

10

10.28 ± 6.34

–

Oubel, Cebral¹²

18

8.29 ± 5.73

–

Karmonik, Diaz¹⁷

7

10.01 ± 5.80

–

Kuroda, Kinoshita²²

22

6.88 ± 4.33

–

Firouzian, Manniesing²⁰

19

–

7.63 ± 3.67

Illies, Saring¹⁵

10

–

8.12 ± 4.27

Illies, Saering⁵

14

9.07 ± 3.75

–

Kunitomi, Watanabe²¹

8

10.89 ± 6.46

–

Gu, Zhang²⁸—irregular

25

–

5.3 ± 2.0

Gu, Zhang²⁸—regular

40

–

4.9 ± 1.6

Kleinloog, Zwanenburg¹⁶

9

6.69 ± 2.67

–

Dissaux, Ognard¹⁹

15

4.43 ± 2.78

–

Total

207