Table 1

Comparison of patient and disease characteristics of early axial spondyloarthritis according to the arm (imaging vs clinical) of the ASAS criteria they met

ASAS criteria
CharacteristicImaging*(N=262)Clinical(N=173)p Value†
Age (years), mean±SD30.6±7.232.6±7.30.005
Female gender, n (%)107 (40.8)101 (58.4)0.0003
Disease duration (months), mean±SD18.6±10.519.2±11.20.683
History or current symptoms of: n (%)
 Enthesitis112 (42.8)86 (49.7)0.154
 Peripheral arthritis56 (41.2)34 (35.1)0.344
 Dactylitis36 (13.7)20 (11.6)0.506
 Uveitis27 (10.3)12 (6.9)0.229
 Psoriasis42 (16.0)28 (16.2)0.966
 Inflammatory bowel disease14 (5.3)5 (2.9)0.221
HLAB27 positivity, n (%)192 (73.6)173 (100.0)<0.0001
Family history of SpA, n (%)110 (44.4)84 (50.0)0.257
BASDAI, mean±SD41.3±20.444.0±20.20.169
CRP (mg/L), mean±SD11.6±15.75.2±9.3<0.0001
Raised CRP‡, n (%) (N=459)111 (44.4)32 (18.8)<0.0001
ASDAS-CRP, mean±SD2.6±1.12.3±1.00.006
BASFI, mean±SD (N=4730)28.7±22.229.3±22.50.840
BASMI, mean±SD (N=463)2.4±1.02.1±0.90.020
Mental SF36, mean±SD41.3±11.540.5±10.80.420
Physical SF36, mean±SD40.9±9.039.8±9.60.191
Radiological sacroiliitis, n (%)173 (66.3)0 (0.0)<0.0001
MRI acute inflammation of the SIJ, n (%)215 (83.7)0 (0.0)<0.0001
  • *Either definite SIJ damage on pelvic x-ray examination according to the modified New York criteria8 or inflammatory lesion of the SIJs on MRI as defined in the Methods section.

  • †Statistical significance defined by p<0.05. Categorical variables were compared using the χ2 test (or Fisher exact test when the χ2 test was not applicable), while continuous variables were compared using the Student t test (or the non-parametric Wilcoxon test when the Student t test was not applicable).

  • ‡Raised CRP defined as CRP >6 mg/L.

  • ASAS, Assessment of Spondyloarthritis International Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Function Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C-reactive protein; SF36, Short Form 36 Health Survey Questionnaire; SIJ, sacroiliac joint; SpA, spondyloarthritis.