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 | |||
|---|---|---|---|
| Characteristic | Imaging*(N=262) | Clinical(N=173) | p Value† |
| Age (years), mean±SD | 30.6±7.2 | 32.6±7.3 | 0.005 |
| Female gender, n (%) | 107 (40.8) | 101 (58.4) | 0.0003 |
| Disease duration (months), mean±SD | 18.6±10.5 | 19.2±11.2 | 0.683 |
| History or current symptoms of: n (%) | |||
| Enthesitis | 112 (42.8) | 86 (49.7) | 0.154 |
| Peripheral arthritis | 56 (41.2) | 34 (35.1) | 0.344 |
| Dactylitis | 36 (13.7) | 20 (11.6) | 0.506 |
| Uveitis | 27 (10.3) | 12 (6.9) | 0.229 |
| Psoriasis | 42 (16.0) | 28 (16.2) | 0.966 |
| Inflammatory bowel disease | 14 (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±SD | 41.3±20.4 | 44.0±20.2 | 0.169 |
| CRP (mg/L), mean±SD | 11.6±15.7 | 5.2±9.3 | <0.0001 |
| Raised CRP‡, n (%) (N=459) | 111 (44.4) | 32 (18.8) | <0.0001 |
| ASDAS-CRP, mean±SD | 2.6±1.1 | 2.3±1.0 | 0.006 |
| BASFI, mean±SD (N=4730) | 28.7±22.2 | 29.3±22.5 | 0.840 |
| BASMI, mean±SD (N=463) | 2.4±1.0 | 2.1±0.9 | 0.020 |
| Mental SF36, mean±SD | 41.3±11.5 | 40.5±10.8 | 0.420 |
| Physical SF36, mean±SD | 40.9±9.0 | 39.8±9.6 | 0.191 |
| 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.