Table 1

Characteristics of axSpA patients at inclusion for all axSpA patients and at first radiograph for patients with available spinal radiographs at intervals of 2 years

Characteristics(A) axSpA patients fulfilling the ASAS classification criteria
N=2977
(B) axSpA patients with available spinal radiographs
N=505
N
2977
Women
N=1210
Men
N=1767
P valueN
505
Women
N=188
Men
N=317
P value
Age, years297739.3 (11.2)39.3 (11.6)0.7750541.5 (10.7)39.5 (11.2)0.06
Symptom duration291011.6 (10.5)13.5 (11.4)<0.00149713.0 (10.4)12.4 (9.6)0.67
HLA-B27 positive, N (%)2724768 (70.0)1368 (84.1)<0.001451117 (70.9)240 (83.9)0.002
r-axSpA1818415 (61.1)908 (79.7)<0.001505141 (75.0)278 (87.7)<0.001
Elevated CRP, N (%)2683332 (30.5)699 (43.8)<0.00142139 (26.7)125 (45.5)<0.001
CRP mg/L26988.5 (14.4)12.2 (17.7)<0.0014227.4 (10.1)11.1 (12.7)<0.001
ASDAS-CRP21933.0 (1.0)2.9 (1.1)0.394072.7 (1.0)2.9 (1.1)0.04
BASDAI24115.1 (2.2)4.4 (2.3)<0.0014264.5 (2.2)4.2 (2.3)0.20
BASFI24323.4 (2.5)3.2 (2.6)0.014323.0 (2.5)3.0 (2.5)0.89
BASMI27211.6 (1.5)2.3 (2.1)<0.0014341.6 (1.7)2.3 (2.5)<0.001
mSASSS5052.3 (6.7)7.8 (13.5)<0.001
No of syndesmophytes5050.6 (2.3)2.6 (4.8)<0.001
 Cervical5050.4 (1.5)1.2 (2.7)<0.001
 Lumbar5050.2 (1.1)1.3 (2.9)<0.001
Syndesmophytes yes/no, N (%)50529 (15.4)126 (39.8)<0.001
Current peripheral arthritis, N (%)2921399 (33.6)495 (28.6)0.00443950 (32.0)82 (29.0)0.52
EQ-5D239660.1 (21.2)63.1 (22.8)<0.00142863.0 (20.7)65.5 (21.1)0.19
SF-12 mental score228842.3 (11.4)44.8 (11.4)<0.00140245.1 (11.3)46.0 (11.2)0.47
SF-12 physical score228837.3 (9.9)39.6 (10.2)<0.00140240.1 (10.1)40.3 (10.0)0.82
On NSAID, N (%)2736970 (85.9)1379 (85.8)0.96400122 (83.0)215 (85.0)0.67
On TNF inhibitor, N (%)2976295 (24.4)447 (25.3)0.5850565 (34.6)104 (32.8)0.70
Current smoker, N (%)2381303 (31.1)559 (39.8)<0.00142650 (33.3)108 (39.1)0.25
Body mass index, kg/m2277624.9 (5.0)25.8 (4.2)<0.00143024.4 (4.8)25.7 (3.9)0.002
No of exercise sessions/week23682.5 (2.5)2.4 (2.5)0.264222.3 (2.1)2.7 (2.7)0.58
Radiographic intervals, N (%)5050.50
1 interval216 (68.1)136 (72.3)
2 intervals64 (20.2)36 (19.1)
3 intervals29 (9.2)12 (6.4)
4 intervals8 (2.5)3 (1.6)
5 intervals0 (0.0)1 (0.5)
  • When not otherwise mentioned, values are the mean (SD). AxSpA patients with available of ≥2 sets of spinal radiographs at intervals of 2 years (±1 year) at first radiograph. (A) All axSpA patients. (B) Patients with r-axSpA.

  • ASAS, Assessment in SpondyloArthritis International Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; aXSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C reactive protein; EQ-5D, European Quality of life questionnaire with five domains; HLA-B27, human leucocyte antigen B27; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs; r-axSpA, radiographic-aXSpA; SF-12, Short Form 12; TNF, tumour necrosis factor.