Table 1 Characteristics of the 38 studies included in the meta-analysis

Bi et al. [22]

67.2 + 4.9

65.5 + 6.8

Retrospective study

26/34

II, 60

Boudard et al. [23]

64.1 + 15.8

49.6 + 17.5

Retrospective study

30/33

III, 21; IV, 9/III, 21; IV, 12

Chen and Chen [24]

61.86 + 5.03

62.03 + 5.14

Retrospective study

46/64

II/III

Cheng et al. [25]

54.0 + 12.5

55.8 + 13.3

Retrospective study

54/54

III, 32; IV, 22/III, 36; IV, 18

Cui et al. [26]

55.4 + 5.8

57.5 + 5.8

Retrospective study

23/25

II, 48

Ding et al. [27]

74.3 + 3.4

74.2 + 3.3

Retrospective study

25/60

II, 17; III, 8/II, 37; III, 23

Dong et al. [28]

4.02 + 0.78

3.92 + 0.88

Retrospective study

17/32

II, 11; III, 6/II, 21; III, 10; IV, 1

Gadea et al. [29]

64

57

Retrospective study

54/53

IV, 107

Gracitelli et al. [30]

64.5 + 9.3

66.4 + 8.1

RCT

32/33

II, 16; III, 16/II, 16; III, 17

Gradl et al. [31]

63 + 16

63 + 16

Prospective

76/76

II, 52; III, 60; IV, 40

Ke [32]

51.3 + 4.6

50.2 + 4.9

Retrospective study

40/40

II, 80

Konrad et al. [33]

64.8 + 13.0

65.4 + 15.6

Prospective

58/153

III, 211

Li [34]

74

76

Retrospective study

29/25

II, 12; III, 17/II, 11; III, 14

Li et al. [35]

74

76

Retrospective study

29/25

II, 12; III, 17/II, 11; III, 14

Matziolis et al. [36]

55.6 + 16.5

54.8 + 16.9

Retrospective study

11/11

II, 22

Pan et al. [37]

69.2 + 8.83

69.15 + 8.08

Retrospective study

30/40

III, 19; IV 14/III, 23; IV, 17

Pu [38]

55.8 + 4.7

56.6 + 4.3

Retrospective study

27/27

NA

Qi [39]

NA

NA

Retrospective study

31/38

II/III

Shao et al. [40]

55.9 + 12.4

55.7 + 12.3

Retrospective study

34/34

II, 30; III, 21

Shen [41]

67

67

Retrospective study

22/24

II, 46

Shi et al. [42]

65.4 + 4.5

61.7 + 5.9

Retrospective study

33/37

II, 17; III, 21/II, 21; III, 16

Sui et al. [43]

59.61 + 6.71

58.32 + 6.54

Retrospective study

15/15

II, 4; III, 7; IV, 4/II, 5; III, 7; IV, 3

Tian et al. [44]

56.3 + 4.6

56.3 + 4.6

Retrospective study

30/30

NA

Trepat et al. [45]

64.5

68.3

Prospective

15/14

II, 29

Urda et al. [46]

70.92 + 11.4

71 + 13.54

Retrospective study

26/15

II, 41

Wang et al. [47]

63.4

63.4

Retrospective study

48/55

II, 21; III, 19; IV, 8/II, 3; III, 14; IV, 38

Wang [48]

61.8 + 4.7

62.2 + 4.1

Retrospective study

28/40

II, 68

Wang and Sheng [49]

76.9 + 4.5

76.5 + 4.7

Retrospective study

45/45

NA

Wu [50]

47.5 + 2.5

48.8 + 1.5

Retrospective study

43/43

NA

Xu et al. [51]

56.0 + 17.4

64.6 + 16.2

Retrospective study

14/24

II, 8; III, 5; IV, 1/II, 7; III, 11; IV, 6

Xue [52]

65.15 + 8.74

66.14 + 8.81

Retrospective study

40/40

II, 27; III, 13/II, 26; III, 14

Yu [53]

62.7 + 10.5

61.9 + 11.2

Retrospective study

46/46

II, 19; III, 22; IV, 5/II, 18; III, 19; IV, 9

Yu et al. [54]

59.3

59.3

Retrospective study

26/26

II, 20; III, 5; IV, 1/II, 21; III, 4; IV, 1

Zhou et al. [55]

46.46 + 5.78

43.45 + 6.34

Retrospective study

25/26

II, 30; III, 21

Zhou et al. [56]

65.2 + 3.6

64.5 + 4.7

Retrospective study

63/64

III, 127

Zhu et al. [57]

54.8 + 17.1

50.5 + 19.9

RCT

25/26

II, 51

Lekic et al. [58]

60

59

Retrospective study

12/12

II, 24

Tamimi et al. [59]

65.3

65.3

Retrospective study

10/22

II, 8; III, IV, 2/II, 2; III, IV, 20