Table 1 Baseline characteristics of patients included in the study

Sex, n (%;95% CI)

♂ 60 (71.4; 61.1, 80.3)

♀ 24 (28.6; 19.7, 38.9)

Age in years, mean (± SD)

59 (± 13)

Body mass index in kg/m², mean (± SD)

28.9 (± 4.7)

Presence of syndesmophytes, n (%;95% CI)

40 (47.6; 37.1, 58.3)

Presence of osteophytes, n (%;95% CI)

18 (21.4; 13.6, 31.2)

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

43 (51.2; 40.6, 61.8)

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

41 (48.8; 38.3, 59.5)

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

 > 10 years

55 (65.5; 54.9, 75)

 5–10 years

17 (20.2; 12.7, 29.8)

 < 5 years

12 (14.3; 7.9, 23)

 BASDAI, mean (± SD) (n = 52)

3.7 (± 2.2)

 BASFI, mean (± SD) (n = 52)

4.3 (± 2.3)

 ASDAS, mean (± SD) (n = 38)

2.7 (± 0.9)

 CRP mg/L, median (IQR)

5 (53)

 ESR mm/h, median (IQR)

9 (57)

 25-OH-D ng/dL, median (IQR) (n = 78)

24 (66)

 Blood calcium mg/dL, mean (± SD) (n = 76)

9.4 (± 0.4)

 24-h urinary calcium, median (IQR) (n = 33)

143 (421)

 PTH pg/mL, median (IQR) (n = 40)

47 (114)

 ALP UI/L, median (IQR) (n = 70)

71.5 (180)

 β-CTX pg/mL, median (IQR) (n = 45)

374 (901)

Lumbar spine T-score

 Osteoporosis, n (%;95% CI)^a

6 (7.2; 3, 14.4)

 Osteopenia, n (%;95% CI)^a

10 (12;6.3, 20.4)

Hip T-score

 Osteoporosis, n (%;95% CI)^a

12 (14.8; 8.3, 23.9)

 Osteopenia, n (%;95% CI)^a

18 (22.2; 14.2, 32.2)

Lumbar spine Z-score

 Low bone mass, n (%;95% CI)^a

2 (2.4;0.4, 7.7)

Hip Z-score

 Low bone mass, n (%;95% CI)^a

0

TBS range (n = 81)

 Low, n (%;95% CI)

14 (17.3; 10.2, 26.7)

 Intermediate, n (%;95% CI)

18 (22.2; 14.2, 32.2)

 Presence of vertebral fracture, n (%;95% CI)

10 (11.9; 6.2, 20.2)