Clinical characteristics of patients with AS
| Variables | No of patients with data | Value |
| Age at diagnosis, mean (SD), year | 338 | 33.1 (9.8) |
| Female (%) | 338 | 35 (10) |
| Disease duration, mean (SD), year | 338 | 12.6 (3.6) |
| Duration treated with TNFis per patient, mean (SD), year | 338 | 6.6 (3.4) |
| Duration not treated with TNFis per patient, mean (SD), year | 338 | 1.8 (2.1) |
| HLA-B27 (%) | 336 | 329 (97.9) |
| Eye involvement (%) | 309 | 142 (46.0) |
| Peripheral joint involvement (%) | 305 | 170 (55.7) |
| ESR at baseline, mean (SD), mm3/hour | 338 | 36.9 (32.1) |
| CRP at baseline, mean (SD), mg/dL | 338 | 2.6 (2.6) |
| mSASSS at baseline, mean (SD) | 338 | 17.0 (18.6) |
AS, ankylosing spondylitis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; cDMARDs, conventional disease-modifying anti-rheumatic drugs; CRP, C-reactive protein; ESR, erythrocyte sedimentation rate; HLA, human leucocyte antigen; mSASSS, modified Stoke Ankylosing Spondylitis Spinal Score; NSAIDs, non-steroidal anti-inflammatory drugs; TNFis, tumour necrosis factor inhibitors.