Table 1 Comparison of patient characteristics in the first admission between the two groups

Age (years)

53.5 ± 9.6

52.6 ± 8.9

0.389

0.699

Sex (Male/Female)

10/11

30/33

-

-

BMI (kg/m²)

27.6 ± 2.7

28.0 ± 4.0

-0.436

0.664

Diagnosis

  OPLL + OFL

9 (42.9 %)

9 (14.3 %)

  OFL

9 (42.9 %)

38 (60.3 %)

  OPLL

2 (9.5 %)

12 (19.0 %)

  TDH

1 (4.7 %)

4 (6.3 %)

4.317

0.038

Number of levels involved

  Less than 3 levels

7

25

  3 or more levels

14

38

0.269

0.604

Comorbidity

  Hypertension

4

11

  Diabetes

3

6

  Cardiovascular disease

1

2

Total

9

19

1.143

0.285