Table 2 Basic demographic characteristics of all participants

N

59

89

88

74

52

40

Sex

0.250

0.907

0.373

 Male

20

29

29

21

21

18

 Female

39

60

59

53

31

22

Age, year

13.66 ± 2.85

12.66 ± 2.38

0.104

12.00 ± 1.58

12.45 ± 1.06

0.145

13.20 ± 2.30

13.74 ± 1.11

0.343

Height, cm

144.33 ± 14.95

148.77 ± 11.97

0.158

151.22 ± 11.65

152.14 ± 8.88

0.699

157.40 ± 15.31

157.75 ± 5.04

0.922

Weight, kg

37.13 ± 7.70

39.28 ± 7.28

0.223

40.38 ± 11.45

43.14 ± 9.16

0.248

45.40 ± 10.51

45.00 ± 3.62

0.871

Cobb angle, degree

55.58 ± 15.86

56.01 ± 21.98

0.873

61.04 ± 20.57

60.14 ± 18.65

0.735

67.00 ± 17.45

65.43 ± 20.54

0.856

Preoperative hemoglobin, g/dL

13.53 ± 1.21

13.32 ± 1.62

0.544

13.35 ± 1.01

13.07 ± 0.51

0.134

13.58 ± 1.02

14.12 ± 0.76

0.054

Preoperative hematocrit, %

39.26 ± 3.54

39.13 ± 2.04

0.731

40.01 ± 0.45

39.62 ± 4.501

0.550

39.72 ± 1.94

39.786 ± 3.33

0.331