Table 1

Baseline characteristics of patients in the SPACE-cohort and the ASAS-cohort; SpA versus no-SpA based on the diagnosis of the rheumatologist

SPACE-cohort*ASAS-cohort*
axSpA (n=65)no-SpA (n=92)p ValueaxSpA (n=421)no-SpA (n=264)p Value
Age (years) at inclusion, mean±SD31.5±16.631.1±8.80.8631.0±10.835.8±10.50.839
Male, n (%)29 (44.6)23 (25.0)0.01225 (53.4)87 (33.0)<0.001
Duration of back pain, mean±SD13.4±7.4 (months)13.7±7.1 (months)0.796.3±7.8 (years)9.3±10.7 (years)0.792
HLA-B27 positive, n (%)44 (67.7)9 (9.8)<0.001270 (64.1)73 (27.7)<0.001
Pos. fam. history SpA, n (%)31 (47.7)25 (27.2)0.01106 (25.2)52 (19.7)0.097
IBP, n (%)52 (80.0)53 (57.6)0.003 324 (77.0)125 (47.3)<0.001
Psoriasis, n (%)10 (15.4)6 (6.5)0.0736 (8.6)13 (4.9)0.073
Dactylitis, n (%)4 (6.2)2 (2.2)0.2028 (6.7)5 (1.9)0.005
Enthesitis, n (%)10 (15.4)15 (16.3)0.8886 (20.4)38 (14.4)0.046
Uveitis, n (%)10 (15.4)5 (5.4)0.0443 (10.2)21 (8.0)0.323
IBD, n(%)4 (6.2)5 (5.4)0.8514 (3.3)4 (1.5)0.149
Preceding infection, n (%)2 (3.1)0 (0.0)0.0912 (0.17)5 (0.14)0.434
CRP (mg/l), mean±SD8.3±11.65.7±6.90.117.1±14.92.4±4.4<0.001
ESR (mm/h), mean±SD13.6±16.310.4±10.70.17
Alternating buttock pain, n (%)15 (23.1)18 (19.6)0.60174 (41.3)65 (24.6)<0.001
Good response to NSAIDs, n (%)27 (41.5)27 (29.3)0.11259 (61.5)73 (27.7)<0.001
Elevated CRP/ESR, n (%) 15 (23.1)16 (17.4)0.38170 (40.4)43 (16.3)<0.001
Arthritis, n (%)13 (20.0)10 (10.9)0.11171(40.6)59 (22.3)<0.001
Sacroiliitis x-ray, n (%)11 (16.9)1 (1.1)<0.001123 (29.2)9 (3.4)<0.001
Sacroiliitis MRI, n (%)27 (41.5)0 (0.0)<0.001202 (48)8 (3)<0.001
  • p Values <0.05 are defined as statistically significant.

  • *Diagnosis according to rheumatologist.

  • †Not estimated in ASAS-cohort.

  • ASAS, Assessment of SpondyloArthritis international Society; AxSpA, axial Spondyloarthritis; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; HLA-B27, Human Leukocyte Antigen; IBD, Inflammatory Bowel Disease; IBP, Inflammatory Back Pain; preceding infection can be balinitis, urethritis, cervicitis and/or acute diarrhoea; SPACE, SPondyloArthritis Caught Early.