Clinical characteristics of subjects
| AxSpA (physician diagnosis) | Not axSpA | Test of significance P value | |
| Number of subjects | 17 (23.3%) | 56 (76.7%) | N/A |
| Mean age in years (SD) | 48.9 (12.0) | 47.6 (11.8) | 0.699 |
| Female | 9 (52.9%) | 37 (66.1%) | 0.394 |
| Human leucocyte antigen-B27 positive | 9 (52.9%) | 19 (25.0%) | 0.167 |
| Smoking status current/ex/never (%) | 35.3/17.6/47.1 | 12.7/40.0/45.5 | 0.093 |
| Mean number of episodes of uveitis— patient reported (SD) | 7.4 (13.9) | 3.9 (5.2) | 0.124 |
| Psoriasis | 1 (5.9%) | 6 (10.7%) | 1.000 |
| Inflammatory bowel disease | 4 (23.5%) | 1 (1.8%) | 0.009* |
| Reported history of peripheral joint swelling | 3 (17.6%) | 10 (17.9%) | 1.000 |
| Family history of axSpA | 1 (5.9%) | 3 (5.4%) | 1.000 |
| Mean duration of back pain in years (SD) | 23.6 (13.2) | 17.8 (10.3) | 0.061 |
| Mean duration of back pain at first episode of uveitis in years (SD) | 16.2 (12.5) | 14.5 (10.7) | 0.511 |
| Maastricht Ankylosing Spondylitis Enthesitis Score (SD) | 0.47 (0.87) | 0.59 (1.37) | 0.738 |
| Joint count (SD) | 0.88 (2.55) | 0.98 (4.84) | 0.935 |
| Bath Ankylosing Spondylitis Metrology Index (SD) | 1.64 (1.32) | 0.69 (0.95) | 0.001* |
| Bath Ankylosing Spondylitis Functional Index (SD) | 2.88 (2.21) | 2.52 (2.27) | 0.564 |
| Bath Ankylosing Spondylitis Global Score (SD) | 4.66 (1.41) | 4.52 (2.01) | 0.782 |
| Bath Ankylosing Spondylitis Disease Activity Index (SD) | 3.36 (1.66) | 3.42 (1.92) | 0.904 |
| Spinal pain Visual Analogue Score (SD) | 4.47 (2.07) | 4.42 (2.42) | 0.936 |
| Elevated C-reactive protein | 5 (29.4%) | 3 (5.4%) | 0.014* |
| Meets Assessment of Spondyloarthritis International Society inflammatory back pain criteria | 6 (35.3%) | 23 (41.1%) | 0.781 |
Test of significance is two-tailed t-test for continuous variables and χ2 test or Fisher’s exact probability test for categorical variables. Unless otherwise indicated values are n (%).
*Statistical significance.
AxSpA, axial spondyloarthritis; N/A, not applicable.