Clinical characteristics, disease activity and treatment of ASAS axial spa versus ASAS peripheral SpA
| ASAS axial SpA | ASAS peripheral SpA | P value | |
| (n=230) | (n=84) | ||
| Age, median (IQR) years | 41 (33–52) | 48 (37–56) | 0.005 |
| Disease duration, median (IQR) years | 3.9 (0.9–11.6) | 4.2 (1.7–10.2) | 0.601 |
| Age at disease onset, median (IQR) years | 32 (24–41) | 38 (31–48) | 0.001 |
| Time to diagnosis, median (IQR) years | 1.0 (0.2–4.0) | 0.7 (0.1–2.6) | 0.172 |
| Male gender, n % | 145 (63) | 49 (58) | 0.447 |
| HLA-B27 positive, % | 170 (76) | 18 (27) | <0.001 |
| Back pain (history/presence), % | 230 (100) | 18 (21) | <0.001 |
| mNY criteria, % | 161 (70) | 0 (0) | <0.001 |
| Peripheral arthritis (history/presence), % | 75 (33) | 82 (98) | <0.001 |
| Enthesitis (history/presence), % | 73 (32) | 40 (48) | 0.009 |
| Dactylitis (history/presence), % | 9 (4) | 10 (12) | 0.009 |
| Uveitis (history/presence), % | 59 (26) | 5 (6) | <0.001 |
| Psoriasis (history/presence), % | 23 (10) | 45 (54) | <0.001 |
| IBD (history/presence), % | 14 (6) | 14 (16.7) | 0.004 |
| Positive SpA family history, % | 86 (37) | 23 (27) | 0.099 |
| Patient's global assessment, median (IQR) 0–100 mm | 55 (30–72) | 38 (17–68) | 0.006 |
| Physician's global assessment, median (IQR) 0–100 mm | 48 (27–61) | 31 (13–44) | <0.001 |
| BASDAI, median (IQR) | 4.9 (3.5–6.4) | 3.0 (1.5–5.4) | <0.001 |
| BASDAI ≥4, % | 149 (66) | 30 (38) | <0.001 |
| BASDAI #2 back pain, median (IQR) | 6.0 (3.7–7.9) | 1.2 (0.1–4.4) | <0.001 |
| ASDAS-CRP, median (IQR) | 2.8 (2.0–3.5) | 2.0 (1.4–3.1) | <0.001 |
| ASDAS-CRP ≥2.1, % | 137 (75) | 32 (46) | <0.001 |
| SJC, median (IQR) 0–66 joints | 0.0 (0.0–0.0) | 1.0 (0.0–2.0) | <0.001 |
| TJC, median (IQR) 0–68 joints | 0.0 (0.0–2.0) | 1.0 (0.0–5.0) | <0.001 |
| Schober, median (IQR) cm | 3.5 (2.5–4.5) | 4.5 (4.0–5.0) | <0.001 |
| CRP, median (IQR) mg/L | 3.6 (1.0–11.7) | 3.7 (1.8–9.6) | 0.479 |
| ESR, median (IQR) mm/h | 9.0 (5.0–20.0) | 7.5 (3.3–18.0) | 0.474 |
| NSAIDs, % | 172 (75) | 47 (56) | 0.001 |
| Corticosteroids, % | 4 (2) | 5 (6) | 0.048 |
| Any csDMARD, % | 32 (13.9) | 56 (67) | <0.001 |
| Anti-TNF therapy, % | 36 (15.7) | 19 (23) | 0.137 |
Significance of the comparisons is determined by Mann-Whitney U tests for continuous variables or χ2 tests for categorical variables. Data were missing for diagnostic delay n=153, HLA-B27 n=25, BASDAI n=10, CRP n=57, SJC/TJC n=2, Schober n=11 and ESR n=47 individuals.
ASAS, Assessment of SpondyloArthritis international Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C reactive protein; csDMARD, conventional synthetic disease-modifying antirheumatic drug; ESR, erythrocyte sedimentation rate; IBD, inflammatory bowel disease; mNY, modified New York.NSAID, non-steroidal anti-inflammatory drug; SJC, swollen joint count; SpA, spondyloarthritis; TJC, tender joint count; TNF, tumour necrosis factor;