Clinical characteristics of study patients at baseline, by AS/nr-axSpA
| Characteristics | AS (n=39) | nr-axSpA (n=36) | All patients (n=75) | p-Value |
|---|---|---|---|---|
| Age in years, mean (SD) | 32.8 (7.9) | 32.9 (9.1) | 32.9 (8.4) | 0.932* |
| Disease duration (back pain duration) in years, mean (SD) | 3.1 (1.7) | 2.5 (1.7) | 2.8 (1.7) | 0.1* |
| Male patients, n (%) | 22 (56.4) | 21 (58.3) | 43 (57.3) | 0.866† |
| HLA-B27 positive, n (%) | 34 (87.2) | 28 (77.8) | 62 (82.7) | 0.283† |
| BASDAI (0–10), mean (SD) | 5.8 (1.3) | 5.7 (1.3) | 5.8 (1.3) | 0.734‡ |
| BASFI (0–10), mean (SD) | 4.4 (2) | 4.3 (2.1) | 4.3 (2) | 0.883‡ |
| Number of swollen joints, joint count (0–64), mean (SD) | 1 (1.6) | 2.8 (6) | 1.9 (4.4) | 0.0923‡ |
| Enthesitis score (0–17), mean (SD) | 3.9 (4.2) | 4 (4.1) | 4 (4.1) | 0.93‡ |
| BASMI (0–10), mean (SD) | 1.8 (1.7) | 1.8 (1.4) | 1.8 (1.5) | 0.977‡ |
| CRP (ref<5 mg/l), mean (SD) | 10.5 (12.2) | 10.5 (12.6) | 10.5 (12.3) | 0.929* |
| No. of patients with raised CRP (CRP>5 mg/l) n (%) | 21 (53.8) | 18 (50) | 39 (52) | 0.739† |
| Presence of clinical arthritis, n (%) | 7 (18) | 12 (33.3) | 19 (53.3) | 0.126† |
| Presence of clinical enthesitis, n (%) | 22 (56.4) | 22 (26.1) | 44 (58.7) | 0.68† |
*Wilcoxon test.
†χ2 test.
‡t test.
AS, ankylosing spondylitis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Disease Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; CRP, C-reactive protein (reference range<5 mg/l); nr-axSpA, non-radiographic axial spondyloarthritis.