Baseline characteristics
| Psoriatic arthritis (n=18) | Spondyloarthritis (n=18) | Healthy subjects (n=12) | |
|---|---|---|---|
| Age (years) | 49 (37–58)* | 42 (32–52) | 32 (27–47) |
| Female (n, %) | 11 (61) | 8 (44) | 8 (67) |
| Symptom duration (years) | 4 (2–14) | 16 (8–27) | NA |
| BASDAI (0–100 mm VAS) | 44 (19–70) *** | 56 (46–68)*** | 2 (1–4) |
| BASDAI question 4 (0–100 mm VAS) | 46 (32–73)*** | 54 (35–67)*** | 1 (0–5) |
| Pain (0–100 mm VAS) | 41 (17–79)*** | 49 (25–69)*** | 1 (0–4) |
| Patient global (0–100 mm VAS) | 57 (19–75)*** | 59 (26–76)*** | 1 (0–2) |
| Physician global (0–100 mm VAS) | 43 (30–64)*** | 24 (18–38)** | 0 (0–0) |
| ASDAS score | 2.6 (1.4–3.4)* | 2.9 (2.0–3.8)* | 1.3 (0.9–1.5) |
| Swollen joint count (0–76) | 5 (3–11)*** | 1 (0–2)* | 0 (0–0) |
| Tender joint count (0–78) | 13 (7–30)*** | 4 (0–17)** | 0 (0–0) |
| C reactive protein (mg/L) | 5 (3–10) | 4 (3–13) | 9 (4–13) |
| Treatment, n (TNFα inhibitor/ NSAIDs/DMARDs/none of these) | 0/6/13/6 | 2/8/5/7 | 0/2/0/10 |
Values are median (IQR) or numbers (percentages). p Values are *p<0.05; **p<0.005; ***p<0.0005 versus healthy subjects (Mann-Whitney test, Fisher's exact test). Only four healthy subjects had C reactive protein measured (reference concentration for normal levels: below 10 mg/L). Two healthy subjects took NSAIDs on demand (not regularly). BASDAI question 4 addresses tenderness outside the joints that is, ‘enthesitis pain’.
ASDAS, ankylosing spondylitis disease activity score; BASDAI, Bath ankylosing spondylitis disease activity index; DMARDs, disease modifying antirheumatic drugs; NA, not applicable; NSAID; non-steroidal anti-inflammatory drug; TNFα, tumour necrosis factor α; VAS, visual analogue scale.