Comparison of baseline characteristics between patients with and those without anterior chest wall (ACW) pain (univariate analysis).
| Characteristics | Patients with ACW, n = 316 | Patients Without ACW, n = 392 | p |
|---|---|---|---|
| Male sex, % | 45 | 47 | 0.6 |
| Mean age, yrs | 33.6 ± 8.5 | 33.8 ± 8.7 | 0.8 |
| Location of axial involvement since beginning | |||
| Cervical spine, % | 45 | 33 | 0.001 |
| Thoracic spine, % | 67 | 49 | 0.000001 |
| Gluteal, % | 78 | 72 | 0.048 |
| Peripheral articular involvement, % | 63 | 52 | 0.003 |
| Entheses involvement, % | 54 | 45 | 0.009 |
| Diagnosis of ankylosing spondylitis at inclusion, % | 47 | 38 | 0.009 |
| ASAS criteria fulfillment at inclusion, % | 72 | 65 | 0.04 |
| ESSG criteria fulfillment at inclusion, % | 82 | 75 | 0.02 |
| Duration between SpA diagnosis and inclusion, days | 272 | 226 | 0.4 |
| Age at IBP onset, yrs | 31.9 | 32.4 | 0.5 |
| Associated conditions at inclusion | |||
| Reactive arthritis, % | 1.9 | 0.26 | 0.006 |
| SAPHO syndrome, % | 6 | 2.6 | 0.02 |
| Inflammatory bowel disease, % | 5.9 | 2.3 | 0.05 |
| Activity, quality of life | |||
| Patient-acceptable symptom state, % | 37 | 45 | 0.04 |
| BAS-G (0–10) | 5.40 ± 2.59 | 4.84 ± 2.51 | 0.005 |
| BASDAI (0–100) | 47.4 ± 20.2 | 42.4 ± 18.5 | 0.001 |
| ASDAS-CRP | 2.63 ± 1.09 | 2.39 ± 0.97 | 0.003 |
| BASFI (0–100) | 33.5 ± 23.3 | 27.9 ± 21.9 | 0.001 |
| Short Form-36 | |||
| Physical | 38.64 ± 8.95 | 41.04 ± 9.45 | 0.001 |
| Mental | 38.93 ± 11.24 | 41.30 ± 11.15 | 0.005 |
| Health Assessment Questionnaire (0–3) | 0.66 ± 0.52 | 0.54 ± 0.49 | 0.001 |
| ASQoL | 10.11 ± 4.71 | 8.57 ± 5.07 | 0.001 |
| Clinical findings | |||
| Enthesis index (0–13) | 3.65 ± 3.57 | 1.91 ± 2.53 | 0.001 |
| Articular index | 5.84 ± 10.05 | 3.04 ± 6.82 | 0.001 |
| BASMI (0–10) | 2.47 ± 1.04 | 2.32 ± 0.97 | 0.04 |
| Laboratory tests | |||
| HLA-B27, % | 61 | 55 | 0.15 |
| CRP, mg/l | 10.3 ± 16.8 | 7.8 ± 12.0 | 0.02 |
| Hemoglobin, g/dl | 15.3 ± 18.8 | 16.1 ± 17.4 | 0.05 |
| Imaging | |||
| Radiographic sacroiliitis*, % | 54 | 45 | 0.003 |
| mSASSS | 1.17 ± 3.11 | 1.0 ± 2.7 | 0.3 |
↵* Score ≥ 1 (see text for details). CRP: C-reactive protein; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; ASDAS-CRP: Ankylosing Spondylitis Disease Activity Score (CRP based); BASFI: Bath Ankylosing Spondylitis Functional Index; BASMI: Bath Ankylosing Spondylitis Metrology Index; mSASSS: modified Stoke Ankylosing Spondylitis Spinal Score; IBP: inflammatory back pain; ASQoL: Ankylosing Spondylitis Quality of Life questionnaire; BAS-G: Bath Ankylosing Spondylitis Global Score; ASAS: Assessment of Spondyloarthritis International Society; ESSG: European Spondyloarthropathy Study Group; SpA: spondyloarthritis; SAPHO: synovitis, acne, pustolosis, hyperostosis, osteitis.