Table 3 Risk factors for facet joints ankylosis in thoracic spine

sex

 Female

1

 Male

1.09(0.56, 2.11)

0.79

Age, years

 (~ , 30)

1

 (30, 40)

0.59(0.14, 2.47)

0.47

 (40, 50)

0.57(0.22, 1.49)

0.25

 (50, 60)

1.27(0.49, 3.26)

0.62

 (60, 70)

0.31(0.09, 1.12)

0.08

 (70, ~)

0.51(0.16, 1.63)

0.26

Disease duration, years

 (~ , 10)

1

 (10, 20)

1.66(0.82, 3.35)

0.16

 (20, 30)

1.15(0.48, 2.79)

0.75

 (30, 40)

1.46(0.54, 3.96)

0.45

 (40, 50)

1.56(0.95, 4.56)

0.21

Inflammatory back pain

0.39(0.17, 1.87)

0.23

Ever Achilles enthesitis

1.03(0.58, 1.82)

0.93

Ever peripheral arthritis

1.18(0.77, 1.79)

0.45

Ever uveitis

1.26(0.66, 2.43)

0.48

Ever ulcerative colitis

0.46(0.21, 0.99)

0.05

Current smoker

1.03(0.63, 1.69)

0.89

BMI, kg/m²

  < 18.5

1

 18.5–24.9

0.27(0.12, 0.59)

 < 0.01**

  > 24.9

1.45(1.03, 8.57)

0.02*

 Elevated level of CRP

1.02 (0.96, 1.08)

0.58

 Elevated level of ESR

0.99(0.98, 1.01)

0.28

 HLA-B27 positive

0.90(0.56, 1.45)

0.67