Table 1

Clinical, laboratory and imaging characteristics of patients with chronic back pain who had judgement on IBP and who received a final diagnosis

ParameterAxSpANo-axSpA
(n=223)
All
(n=403)
AS
(n=88)
Nr-axSpA
(n=92)
Age, years (mean±SD)36.1±10.232.8±9.342.7±11.339.0±11.4
Male sex, n (%)60 (68.2)54 (58.7)79 (35.4)193 (47.9)
HLA-B27 positive, n (%)79 (89.8)70 (76.1)83 (37.2)232 (57.6)
Back pain duration, years (mean±SD)9.0±7.85.3±6.912.5±10.910.1±9.9
Peripheral oligoarthritis, n (%)12 (13.6)20 (21.7)32 (14.3)64 (15.9)
Enthesitis, n (%)21 (23.9)16 (17.4)33 (14.8)71 (17.6)
Dactylitis, n (%)2 (2.3)5 (5.4)10 (4.5)17 (4.2)
Uveitis, n (%)13 (14.8)18 (19.6)11 (4.9)42 (10.4)
History of IBD, n (%)2 (2.3)4 (4.4)0 (0)6 (1.5)
Psoriasis, n (%)2 (2.3)13 (14.1)16 (7.2)31 (7.7)
SpA family history, n (%)17 (19.3)24 (26.1)45 (20.1)86 (21.3)
CRP, mg/L (mean±SD)11.0±16.47.1±9.22.9±4.35.7±9.9
ESR, mm/hour (mean±SD)22.7±20.815.2±13.312.0±10.315.2±14.6
Radiographic sacroiliitis according to the mNY criteria, n/N (%)78/85 (91.8)0/850/20885/378 (22.5)
Active inflammatory changes in the SIJ on MRI, n/N (%)37/48 (77.1)51/70 (72.9)2/77 (2.6)90/195 (46.2)
Chronic inflammatory changes in the SIJ on MRI, n/N (%)32/48 (66.7)38/70 (54.3)0/77 (0)70/195 (35.9)
Active inflammatory changes in the spine on MRI, n/N (%)15/36 (41.7)13/35 (37.1)5/84 (6.0)33/155 (21.3)
Chronic inflammatory changes in the spine on MRI, n/N (%)11/36 (30.6)3/35 (8.6)3/84 (3.6)17/15 (11.0)
  • AS, ankylosing spondylitis; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; IBD, inflammatory bowel disease; MRI, MRI resonance imaging; SIJ, sacroiliac joint; SpA, spondyloarthritis; mNY criteria, modified New York criteria; nr-axSpA, non-radiographic axial spondyloarthritis.