Table 2

Clinical characteristics of study patients at baseline, by AS/nr-axSpA

CharacteristicsAS (n=39)nr-axSpA (n=36)All patients (n=75)p-Value
Age in years, mean (SD)32.8 (7.9)32.9 (9.1)32.9 (8.4)0.932*
Disease duration (back pain duration) in years, mean (SD)3.1 (1.7)2.5 (1.7)2.8 (1.7)0.1*
Male patients, n (%)22 (56.4)21 (58.3)43 (57.3)0.866†
HLA-B27 positive, n (%)34 (87.2)28 (77.8)62 (82.7)0.283†
BASDAI (0–10), mean (SD)5.8 (1.3)5.7 (1.3)5.8 (1.3)0.734‡
BASFI (0–10), mean (SD)4.4 (2)4.3 (2.1)4.3 (2)0.883‡
Number of swollen joints, joint count (0–64), mean (SD)1 (1.6)2.8 (6)1.9 (4.4)0.0923‡
Enthesitis score (0–17), mean (SD)3.9 (4.2)4 (4.1)4 (4.1)0.93‡
BASMI (0–10), mean (SD)1.8 (1.7)1.8 (1.4)1.8 (1.5)0.977‡
CRP (ref<5 mg/l), mean (SD)10.5 (12.2)10.5 (12.6)10.5 (12.3)0.929*
No. of patients with raised CRP (CRP>5 mg/l) n (%)21 (53.8)18 (50)39 (52)0.739†
Presence of clinical arthritis, n (%)7 (18)12 (33.3)19 (53.3)0.126†
Presence of clinical enthesitis, n (%)22 (56.4)22 (26.1)44 (58.7)0.68†
  • *Wilcoxon test.

  • †χ2 test.

  • ‡t test.

  • AS, ankylosing spondylitis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Disease Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C-reactive protein (reference range<5 mg/l); nr-axSpA, non-radiographic axial spondyloarthritis.