Differential features between patients with axPsA and axSpA.
| AxPsA, n = 24 | AxSpA, n = 64 | P | OR | 95% CI | |
|---|---|---|---|---|---|
| Male sex, n (%) | 10 (42) | 29 (45) | 0.8 | 0.9 | 0.3–2.2 |
| Age at diagnosis, yrs, mean (SD) | 49.4 (9.6) | 43.8 (12.7) | 0.03 | ||
| Smoking, n (%) | 51 (71) | 22 (34) | 0.003 | 4.7 | 1.6–14 |
| Peripheral arthritis, n (%) | 21 (87) | 13 (20) | > 0.001 | 27.6 | 7–106 |
| Enthesitis, n (%) | 11 (46) | 21 (33) | 0.25 | 1.7 | 0.6–4.5 |
| PsO, n (%) | 19 (79) | 0 (0) | > 0.001 | ||
| IBD and/or uveitis, n (%) | 10 (42) | 9 (14) | 0.005 | 4.3 | 1.5–13 |
| Family history of SpA, n (%) | 6 (25) | 20 (31) | 0.5 | 0.7 | 0.2–2.1 |
| Positive peripheral radiograph, n (%) | 10 (59) | 1 (2) | > 0.001 | 61.4 | 7–557 |
| Positive enthesis US, n (%) | 10 (42) | 23 (43) | 0.9 | 1.0 | 0.4–2.9 |
| Positive joints US, n (%) | 10 (45) | 6 (12.5) | 0.002 | 5.8 | 1.7–19 |
| Inflammatory low back pain, n (%) | 21 (91) | 56 (87) | 0.6 | 1.5 | 0.3–7.6 |
| Good response to NSAID, n (%) | 22 (82) | 43 (70) | 0.3 | 1.8 | 0.5–6.3 |
| Positive sacroiliac test, n (%) | 17 (74) | 33 (52) | 0.07 | 2.5 | 0.9–7.3 |
| Morning stiffness, min, median (IQR) | 40 (30–45) | 30 (15–40) | 0.04 | ||
| VAS pain (0–10), median (IQR) | 7 (5–7) | 7 (6–8) | 0.03 | ||
| VAS night pain (0–10), median (IQR) | 7 (5–7) | 6 (4–7.5) | 0.8 | ||
| BASDAI, mean (SD) | 4 (1.7) | 4.5 (1.6) | 0.2 | ||
| BASFI, median (IQR) | 4.6 (3.8–5.3) | 4.6 (4–6) | 0.6 | ||
| MASES, median (IQR) | 0.5 (0–2) | 0 (0–1) | 0.2 | ||
| HAQ-DI, median (IQR) | 0.8 (0.5–1) | 0.75 (0.5–1) | 0.2 | ||
| Positive HLA-B27, n (%) | 4 (17) | 30 (49) | 0.006 | 0.2 | 0.06–0.7 |
| CRP, median (IQR) | 2 (1–10) | 2 (1–6) | 0.6 | ||
| ESR, median (IQR) | 19 (10–25) | 17 (10–25) | 0.6 | ||
| Positive sacroiliac MRI, n (%) | 9 (37) | 44 (72) | 0.003 | 0.2 | 0.85–0.6 |
| Positive sacroiliac radiograph, n (%) | 7 (32) | 30 (52) | 0.1 | 0.4 | 0.14–1.1 |
| Time from onset of low back pain to evaluation, months, median (IQR) | 60 (18–122) | 40 (17–122) | 0.9 |
Values in bold are statistically significant. AxPsA: axial psoriatic arthritis; AxSpA: axial spondyloarthritis; CRP: C-reactive protein; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Functional Index; ESR: erythrocyte sedimentation rate; HAQ-DI: Health Assessment Questionnaire-Disability Index; IBD: inflammatory bowel disease; MASES: Maastricht Ankylosing Spondylitis Enthesitis Score; MRI: magnetic resonance imaging; NSAID: nonsteroidal antiinflammatory drug; PsA: psoriatic arthritis; PsO: psoriasis; SpA: spondyloarthritis; US: ultrasonography; VAS: visual analog scale.