Table 1

Characteristics of the ankylosing spondylitis study population

Total group

Validity study

Reliability study


Number of patients

115

63

52

Age (years)

44.6 ± 12.1

43.2 ± 12.3

46.3 ± 11.8

Gender (male)

71 (62)

40 (64)

31 (60)

Body mass index

26.4 ± 4.4

26.2 ± 4.8

26.6 ± 3.9

Duration of symptoms (years)

16 (0 to 54)

18 (2 to 54)

16 (0 to 53)

Time since diagnosis

10 (0 to 42)

11 (1 to 42)

9 (0 to 37)

HLA-B27+

82 (76)

49 (82)

33 (69)

Anti-TNF use

78 (70)

39 (62)

39 (81)*

NSAID use

44 (40)

24 (39)

20 (42)

DMARD use

17 (15)

13 (21)

4 (8)

BASDAI (range 0 to 10)

3.7 (0.0 to 9.0)

3.8 (0.4 to 8.6)

3.5 (0.0 to 9.0)

ESR (mm/hour)

11 (2 to 60)

13 (2 to 60)

10 (2 to 39)

CRP (mg/l)

3 (2 to 46)

3 (2 to 44)

4 (2 to 46)

ASDASCRP

2.3 (0.7 to 4.4)

2.3 (0.9 to 4.2)

2.3 (0.7 to 4.4)

BASFI (range 0 to 10)

3.8 ± 2.4

3.6 ± 2.4

4.2 ± 2.4

Occiput-to-wall distance (cm)

0.0 (0.0 to 29.0)

0.0 (0.0 to 29.0)

0.0 (0.0 to 20.0)

Chest expansion (cm)

5.0 (1.0 to 14.0)

6.0 (1.0 to 10.5)

4.0 (1.0 to 14.0)**

Modified Schober test (cm)

4.0 (0.4 to 7.0)

4.0 (0.4 to 6.2)

3.9 (0.0 to 7.0)

Lateral spinal flexion (cm)

10.0 (0.0 to 27.0)

10.0 (0.0 to 25.0)

10.0 (1.8 to 27.0)

Cervical rotation (degrees)

63 (5 to 98)

70 (7 to 95)

58 (5 to 98)

ASQoL (range 0 to 18)

6 (0 to 18)

6 (0 to 17)

6 (0 to 18)


Data presented as mean ± standard deviation, n (%) or median (range). ASDAS, Ankylosing Spondylitis Disease Activity Score; ASQoL, Ankylosing Spondylitis Quality of Life; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; CRP, C-reactive protein; DMARD, disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; HLA-B27+, human leukocyte antigen B27-positive; NSAID, nonsteroidal anti-inflammatory drug; TNF, tumor necrosis factor. *Statistically significant difference compared to the validity study (P < 0.05). **Statistically significant difference compared to the validity study (P < 0.01).

Arends et al. Arthritis Research & Therapy 2013 15:R99   doi:10.1186/ar4279

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