Table 2 Univariate analysis of UIROR risk factors

 Age (years)

34.47±14.95

31.48±12.22

.385

 Gender (male/female)

7/8

42/84

.391

 Obesity (obese/none)

3/12

6/120

.046*

 Previous spine surgery history (yes/no)

0/15

18/108

.217

 Duration of spinal deformity history (years)

26.20±15.32

18.86±12.62

.040*

 Previous neurological symptom (yes/no)

10/5

29/97

.001*

 Congenital deformity (yes/no)

11/4

52/74

.026*

 Preoperative Cobb angle of main curve (°)

91.61±30.34

89.62±36.09

.838

 Preoperative flexibility of main curve (%)

16.20±16.98

14.37±14.55

.652

 Preoperative maximum kyphosis angle (°)

77.56±37.87

72.23±43.32

.649

 Preoperative AVR (>II/≤II)

11/4

47/79

.011*

 Total operative time (min)

317.00±110.01

288.65±82.71

.154

 Intraoperative estimated blood loss (ml)

1060.00±701.83

809.92±631.51

.154

 Number of fusion vertebrae

10.20±3.34

10.89±3.36

.454

 ASA (>2/≤2)

1/14

33/93

.118

 Osteotomy (yes/no)

10/5

79/47

.501

 Thoracoplasty (yes/no)

3/12

23/103

.550

 Fusion to sacrum (yes/no)

3/12

8/118

.096