Table 2 Differences in baseline characteristics of patients included in the study regarding syndesmophyte status

Sex, n ♂ / n ♀

38 / 2

22 / 22

 < 0.001

Age in years, mean (± SD)

62 (± 12)

56.2 (± 13.6)

0.004

Body mass index in kg/m², mean (± SD)

30.7 (± 4.5)

27.3 (± 4.4)

0.001

Treatment with NSAIDs / biologics, n (%;95% CI)

22 (55; 39.5, 69.8) / 18 (45; 30.2, 60.5)

21 (47.7; 33.3, 62.4) / 23 (52.3; 37.6, 66.6)

0.505

Disease duration in range of years, n (%;95% CI)

     > 10 years

     5–10 years

      < 5 years

27 (67.5; 51.9, 80.6)

9 (22.5; 11.6; 37.3)

4 ( 10; 3.26, 22.4)

28 (63.6; 48.7, 76.8)

8 (18.2; 8.8, 31.6)

8 (18.2; 8.8, 31.6)

0.543

    BASDAI, mean (± SD) (n = 22/30)

3.8 (± 2.3)

3.6 (± 2.2)

0.651

    BASFI, mean (± SD) (n = 23/29)

4.7(± 2)

3.9 (± 2.6)

0.225

    ASDAS, mean (± SD) (n = 18/20)

2.7 (± 0.9)

2.7 (± 0.8)

0.842

    CRP mg/L, median (IQR)

5 (48)

5 (53)

0.731

    ESR mm/h, median (IQR)

10 (57)

8 (50)

0.435

    25-OH-D ng/dL, median (IQR) (n = 38/40)

23 (66)

24.5 (55)

0.339

    Blood calcium mg/dL, mean (± SD) (n = 38/38)

9.37 (± 0.3)

9.33 (± 0.39)

0.669

    24-h urinary calcium, median (IQR) (n = 18/15)

125 (317)

145 (381)

0.448

    PTH pg/mL, median (IQR) (n = 23/17)

47 (107)

49 (65)

0.891

    ALP UI/L, median (IQR) (n = 31/39)

73 (180)

71 (77)

0.242

    β-CTX pg/mL, median (IQR) (n = 23/22)

352 (901)

396.5 (522)

0.394

    TBS values median (IQR) (n = 39/42)

1.31 (0.58)

1.33 (0.8)

0.187

    Lumbar spine BMD values mean (± SD)

1.37 (± 0.26)

1.14 (± 0.22)

 < 0.001

    Total hip BMD values mean (± SD) (n = 38/43)

0.99 (± 0.17)

0.96 (± 0.16)

0.463

    Femoral neck BMD values mean (± SD) (n = 38/43)

0.88 (± 0.14)

0.87 (± 0.14)

0.820