Table 2 Status and change scores of mSASSS and extended mSASSS

Status score at baseline, mean ± SD

4.2 ± 8.3

8.6 ± 18.0

5.9 ± 10.3

12.8 ± 22.5

2.3 ± 4.2

3.5 ± 7.4

Status score at year 2, mean ± SD

5.0 ± 9.6

9.8 ± 20.0

6.8 ± 11.7

14.5 ± 24.9

2.8 ± 5.3

4.1 ± 8.9

Change score, mean ± SD

0.7 ± 2.3

1.2 ± 3.7

1.0 ± 2.8

1.7 ± 4.6

0.5 ± 1.6

0.6 ± 2.2

Smallest detectable change

4.1

6.4

4.7

7.5

3.3

4.6

Change score ≥ smallest detectable change, n (%)

14 (6.7)

12 (5.7)

7 (6.1)

8 (7.0)

4 (4.2)

6 (6.3)

Presence of syndesmophytes at baseline, n (%)

48 (22.9)

64 (30.5)

35 (30.4)

48 (41.7)

13 (13.7)

16 (16.8)

Presence of syndesmophytes at year 2, n (%)

50 (23.8)

65 (31.0)

36 (31.3)

50 (43.5)

14 (14.7)

15 (15.8)

Total number of syndesmophytes at baseline, mean ± SD

0.9 ± 2.6

1.9 ± 5.2

1.5 ± 3.3

3.2 ± 6.6

0.3 ± 1.1

0.5 ± 1.9

Total number of syndesmophytes at year 2, mean ± SD

1.1 ± 3.1

2.2 ± 6.0

1.7 ± 3.8

3.5 ± 7.6

0.4 ± 1.4

0.6 ± 2.4

Change score ≥ 2 points after 2 years, n (%)

30 (14.3)

44 (21.0)

23 (20.0)

35 (30.4)

7 (7.4)

9 (9.5)

Development of new syndesmophytes after 2 years, n (%)

16 (7.6)

20 (9.5)

13 (11.3)

17 (14.8)

3 (3.2)

3 (3.2)

Development of new /growth of existing syndesmophytes after 2 years, n (%)

18 (8.6)

23 (11.0)

15 (13.0)

20 (17.4)

3 (3.2)

3 (3.2)