| Age (years), Mean (DS) | 33.94 (7.89) | 33.09 (9.55) | 1.01 (0.96–1.06) | 0.65 | | |
| Male (sex), Ref. female | 18 (51.4%) | 28 (50.9%) | 1.02 (0.44–2.38) | 0.96 | 0.15 (0.03–0.77) | 0.023 |
| NSAID response | 28 (80.0%) | 29 (52.7%) | 3.58 (1.34–9.58) | 0.010 | | |
| Chronic Inflamatory Bowel | 1 (2.9%) | 3 (5.4%) | 0.51 (0.05–5.10) | 0.57 | | |
| HLA B-27+ | 22 (62.9%) | 9 (16.4%) | 8.65 (3.21–23.28) | <0.001 | 4.19 (1.11–15.83) | 0.035 |
| C-reactive protein | 16 (45.7%) | 8 (14.5%) | 4.94 (1.82–13.48) | 0.002 | | |
| High erythrocyte sedimentation rate (ESR) | 13 (37.1%) | 6 (10.9%) | 4.82 (1.62–14.36) | 0.005 | | |
| Pathologic sacroiliac joint in X-ray | 22 (62.9%) | 2 (3.6%) | 44.85 (9.33–215.45) | <0.001 | 78.78 (10.20–608.25) | <0.001 |
| Bone marrow edema (BMO)+ | 20 (57.1%) | 7 (12.7%) | 9.14 (3.24–25.81) | <0.001 | | |
| ASAS criteria+ | 27 (77.1%) | 8 (14.5%) | 19.82 (6.68–58.87) | <0.001 | | |