Table 1 Baseline characteristics
Total patients (n = 3942) | Based on available data | Number of patients with missing items | |
|---|---|---|---|
Age at inclusion, years, mean ± SD | 43.6 (13.9) | 0 | |
Male sex, n (%) | 2563 (65.0%) | 0 | |
HLA-B27-positive, n (%) | 2217 (56.2%) | 72.0% | 882 |
IBP, n (%) | 3219 (81.7%) | 52 | |
Morning stiffness, n (%) | 2497 (63.3%) | 22 | |
Enthesitis, n (%) | 1354 (34.3%) | 0 | |
Dactylitis, n (%) | 610 (15.5%) | 3 | |
Psoriasis, n (%) | 843 (21.4%) | 0 | |
Uveitis, n (%) | 771 (19.6%) | 0 | |
Peripheral arthritis, n (%) | 2424 (61.5%) | 0 | |
IBD, n (%) | 209 (5.3%) | 0 | |
Positive family history, n (%) | 1475 (37.4%) | 117 | |
Good response to NSAIDs, n (%) | 2433 (61.7%) | 77.5% | 803 |
Elevated CRP, n (%) | 2109 (53.5%) | 57.7% | 287 |
Preceding infection, n (%) | 271 (6.9%) | 74 | |
Sacroiliitis based on radiograph (mNY), n (%) | 2539 (64.4%) | 70.0% | 341 |
Sacroiliitis based on MRI, n (%) | 1326 (33.6%) | 65.7% | 1951 |
Rheumatoid factor-negative, n (%) | 3177 (80.6%) | 94.8% | 613 |
Psoriatic nail dystrophy, n (%) | 460 (11.7%) | 28 | |
Juxta-articular bone formation, n (%) | 526 (13.3%) | 17.7% | 999 |