Baseline characteristics of the patients with axial spondyloarthritis in GESPIC who included and excluded from the present study
| Parameter | All patients in GESPIC (n=525) | Included patients (n=243) | Excluded patients (n=282) |
| Age, years, mean±SD | 35.7±10.3 | 36.2±10.2 | 35.2±10.4 |
| Male sex, n (%) | 286 (54.5) | 120 (49.4) | 166 (58.9) |
| Symptom duration, years, mean±SD | 3.9±2.7 | 4.0±2.5 | 3.9±2.8 |
| Smoking current, n (%) | 132 (25.1) | 67 (27.6) | 65 (23.1) |
| HLA-B27 positivity, n (%) | 406 (77.9) | 191 (79.3) | 215 (76.8) |
| Positive family history for SpA, n (%) | 159 (30.3) | 85 (35.1) | 74 (26.2) |
| Peripheral arthritis, current, n (%) | 77 (14.7) | 28 (11.5) | 49 (17.4) |
| Enthesitis, current, n (%) | 105 (20.0) | 46 (18.9) | 59 (20.9) |
| Dactylitis, current, n (%) | 27 (5.1) | 13 (5.4) | 14 (5.0) |
| Uveitis ever, n (%) | 86 (16.4) | 45 (18.5) | 41 (14.5) |
| Psoriasis ever, n (%) | 53 (10.1) | 28 (11.5) | 25 (8.9) |
| IBD ever, n (%) | 14 (2.7) | 7 (2.9) | 7 (2.5) |
| CRP, mg/litre, mean±SD | 11.1±17.5 | 11.4±18.8 | 10.9±16.3 |
| ASDAS-CRP, mean±SD | 2.6±1.0 | 2.5±1.0 | 2.6±0.9 |
| BASDAI (0–10 points NRS), mean±SD | 3.9±2.1 | 3.7±2.1 | 4.1±2.1 |
| BASFI (0–10 points NRS), mean±SD | 2.8±2.4 | 2.7±2.3 | 2.8±2.4 |
| BASMI (0–10 points NRS), mean±SD | 1.5±1.6 | 1.6±1.6 | 1.4±1.7 |
| Treatment with NSAIDs, n (%) | 352 (67.1) | 163 (67.1) | 189 (67.0) |
| Treatment with csDMARDs, n (%) | 121 (23.1) | 58 (23.9) | 63 (22.3) |
| Treatment with TNFi, n (%) | 13 (2.5) | 8 (3.3) | 5 (1.8) |
| Treatment with systemic steroids, n (%) | 48 (9.1) | 15 (6.2) | 33 (11.7) |
| Patients with r-axSpA, n (%) | 249 (47.4) | 113 (46.5) | 136 (48.2) |
| mSASSS points, mean±SD | 2.6±5.9 N=378 | 2.6±6.6 N=225 | 2.7±4.9 N=153 |
| ≥1 syndesmophyte, n (%) | 66 (17.5) N=378 | 40 (17.8) N=225 | 26 (17.0) N=153 |
ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C reactive protein; csDMARDs, conventional synthetic disease-modifying antirheumatic drugs; HLA-B27, human leucocyte antigen B27; IBD, inflammatory bowel disease; mSASSS, modified Stroke Ankylosing Spondylitis Spine Score; NRS, numeric rating scale; NSAIDs, non-steroidal anti-inflammatory drugs; SpA, spondyloarthritis; TNFi, tumour necrosis factor alpha inhibitor.