Table 2 Spine X-ray lesions (A: Cervical, B: Thoracic, C: Lumbar; the presence of SpA changes was defined by a positive score for erosions, sclerosis, squaring, syndesmophytes, or bridging syndesmophytes; the presence of degenerative changes was defined by the presence of spondylophytes or bridging spondylophytes)

A: Cervical Spine X-ray lesions

Number of patients evaluated

9

8

3

20

Number of disco-vertebral units evaluated

45

27

7

79

Number of quadrants evaluated

180

108

28

316

Erosions

Quadrants with SpA erosions, N (%)

11 (6.1)

0

1 (3.5)

12 (3.8%)

Patients with SpA erosions, N (%)

5 (55.6)

0

1 (33.3)

6 (30.0)

0.277

Quadrants with erosions per patient

2.2

1

2

Sclerosis

Quadrants with SpA sclerosis, N (%)

0

0

0

0

Patients with SpA sclerosis, N (%)

0

0

0

0

N/A

Quadrants with sclerosis per patient

Squaring

Quadrants with SpA squaring, N (%)

0

0

0

0

Patients with SpA squaring, N (%)

0

0

0

0

N/A

Quadrants with squaring per patient

Syndesmophytes

Quadrants with SpA syndesmophytes, N (%)

5 (2,8)

0

0

5 (1,6)

Patients with SpA syndesmophytes, N (%)

2 (2.22)

0

0

2 (10.0)

0.706

Quadrants with syndesmophytes per patient

2.5

2.5

Bridging syndesmophytes

Quadrants with SpA bridging syndesmophytes, N (%)

0

0

0

0

Patients with SpA bridging syndesmophytes, N (%)

0

0

0

0

N/A

Quadrants with bridging syndesmophytes per patient

Patients with SpA-like changes, N / All patients in the group (%)

6/9 (66.7)^@2

0/8 (0)

1/3 (33.3)

7/20 (35.0)

0.013

Spondylophytes

Quadrants with spondylophytes, N (%)

39 (21.7)

10 (9.3)

9 (32.1)

58 (18.3)

Patients with SpA spondylophytes, N (%)

5 (55.6)

4 (50.0)

2 (66.6)

11 (55.0)

0.913

Quadrants with spondylophytes per patient

7.8

2.5

4.5

5.3

Bridging spondylophytes

Quadrants with bridging spondylophytes, N (%)

10 (5.5)

24 (22.2)

4 (14.3)

38 (12.0)

Patients with SpA bridging spondylophytes, N (%)

5 (55.6)

4 (50.0)

1 (33.3)

10 (50.0)

0.686

Quadrants with bridging spondylophytes per patient

2

6

4

3.8

Patients with degenerative changes N /

All patients in the group (%)

5/9 (55.6)

5/8 (62.5)

2/3 (66.7)

12/20 (60.0)

1.000

B: Thoracic Spine X-ray lesions

Number of patients evaluated

66

36

26

128

Number of disco-vertebral units evaluated

224

172

93

490

Number of quadrants evaluated

896

685

372

1953

Erosions

Quadrants with SpA erosions, N (%)

2 (0.22)

6 (0.88)

1 (0.27)

9 (0.46)

Patients with SpA erosions, N (%)

2 (3.0)

6 (16.7)*¹

1 (3.8)

9 (7.0)

0.038

Quadrants with erosions per patient

1

1

1

1

Sclerosis

Quadrants with SpA sclerosis, N (%)

0

0

0

0

Patients with SpA sclerosis, N (%)

0

0

0

0

N/A

Quadrants with sclerosis per patient

Squaring

Quadrants with SpA squaring, N (%)

0

0

0

0

Patients with SpA squaring, N (%)

0

0

0

0

N/A

Quadrants with squaring per patient

Syndesmophytes

Quadrants with SpA syndesmophytes, N (%)

0

2 (0.29)

0

2 (0.10)

Patients with SpA syndesmophytes, N (%)

0

1 (2.8)

0

1 (0.78)

0.478

Quadrants with syndesmophytes per patient

2

2

Bridging syndesmophytes

Quadrants with SpA bridging syndesmophytes, N (%)

2 (0.22)

12 (1.8)

6 (1.61)

20 (1.02)

Patients with SpA bridging syndesmophytes, N (%)

1 (1.5)

3 (8.3)

2 (7.7)

6 (4.7)

0.154

Quadrants with bridging syndesmophytes per patient

2

4

3

3.3

Patients with SpA-like changes, N / All patients in the group (%)

5/66 (7.6)

10/36 (27.8)*¹

3/26 (11.5)

18/128 (14.1)

0.024

Spondylophytes

Quadrants with spondylophytes, N (%)

176 (19.6)

121 (17.7)

66 (17.7)

363 (18.6)

Patients with SpA spondylophytes, N (%)

47 (71.2)

28 (77.8)

18 (69.2)

93 (72.6)

0.709

Quadrants with spondylophytes per patient

3.7

4.3

3.7

3.9

Bridging spondylophytes

Quadrants with bridging spondylophytes, N (%)

118 (13.2)

182 (26.6)

98 (26.3)

398 (20.4)

Patients with SpA bridging spondylophytes, N (%)

33 (50.0)

32 (88.9)*¹

19 (73.1)^#1

84 (65.6)

< 0.001

Quadrants with bridging spondylophytes per patient

3.6

5.7

5.2

4.7

Patients with degenerative changes N / All patients in the group (%)

58/66 (87.9)

36/36 (100)*¹

25/26 (96.1)

119/128 (93.0)

0.055

C: Lumbar Spine X-ray lesions

Number of patients evaluated

62

32

22

116

Number of disco-vertebral units evaluated

305

141

127

573

Number of quadrants evaluated

1218

563

505

2286

Erosions

Quadrants with SpA erosions, N (%)

17 (1.4)

8 (1.4)

7 (1.4)

32 (1.4)

Patients with SpA erosions, N (%)

12 (19.3)

6 (18.7)

5 (22.7)

23 (19.8)

0.959

Quadrants with erosions per patient

1.4

1.3

1.4

1.4

Sclerosis

Quadrants with SpA sclerosis, N (%)

1 (0.08)

1 (0.18)

2 (0.40)

4 (0.17)

Patients with SpA sclerosis, N (%)

1 (1.6)

1 (3.1)

2 (9.1)

4 (3.4)

0.242

Quadrants with sclerosis per patient

1

1

1

1

Squaring

Quadrants with SpA squaring, N (%)

0

0

0

0

Patients with SpA squaring, N (%)

0

0

0

0

N/A

Quadrants with squaring per patient

Syndesmophytes

Quadrants with SpA syndesmophytes, N (%)

4 (0.33)

0

1 (0.20)

5 (0.22)

Patients with SpA syndesmophytes, N (%)

3 (4.8)

0

1 (4.5)

4 (3.4)

0.526

Quadrants with syndesmophytes per patient

1.3

1

1.2

Bridging syndesmophytes

Quadrants with SpA bridging syndesmophytes, N (%)

2 (0.16)

0

4 (0.79)

6 (0.26)

Patients with SpA bridging syndesmophytes, N (%)

1 (1.6)

0

2 (9.1)

3 (2.6)

0.167

Quadrants with bridging syndesmophytes per patient

2

2

2

Patients with SpA changes, N / All patients in the group (%)

14/62 (22.6)

7/32 (21.9)

11/22 (50.0)^##

32/116 (27.6)

0.033

Spondylophytes

Quadrants with spondylophytes, N (%)

308 (25.3)

174 (30.9)

129 (25.5)

611 (26.7)

Patients with SpA spondylophytes, N (%)

57 (91.9)

28 (87.5)

21 (95.4)

106 (91.4)

0.734

Quadrants with spondylophytes per patient

5.4

6.2

6.1

5.8

Bridging spondylophytes

Quadrants with bridging spondylophytes, N (%)

46 (3.8)

58 (10.3)

42 (8.3)

146 (6.4)

Patients with SpA bridging spondylophytes, N (%)

16 (25.8)

17 (53.0)*¹

11 (50.0)

44 (37.9)

0.036

Quadrants with bridging spondylophytes per patient

2.9

3.4

3.8

3.3

Patients with degenerative changes N / All patients in the group (%)

58/62 (93.5)

30/32 (93.8)

21/22 (95.5)

109/116 (93.9)

1.000