Sensitivity analysis for identification of factors associated with radiographic SIJ progression with alternative disease activity parameters
| Variable | OR | 95% CI | P value |
| Prior TNFi use up to the start of X-ray interval yes/no | 0.22 | 0.08 to 0.60 | 0.003 |
| Baseline sacroiliac damage (0–7) at start of each X-ray interval | 1.32 | 1.00 to 1.75 | 0.047 |
| Female sex | 0.27 | 0.07 to 1.04 | 0.06 |
| Symptom duration | 1.06 | 1.01 to 1.10 | 0.01 |
| Current smoking | 2.46 | 0.75 to 8.11 | 0.14 |
| HLA-B27 negative | 0.77 | 0.16 to 3.83 | 0.75 |
| NSAID use at start of each X-ray interval | 0.90 | 0.26 to 3.10 | 0.86 |
| BASDAI at start of each X-ray interval | 1.02 | 0.81 to 1.29 | 0.88 |
| CRP at start of each X-ray interval | 1.01 | 0.98 to 1.04 | 0.55 |
Analysis in 302 patients and 483 X-ray intervals (22 events).
BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C-reactive protein; HLA-B27, human leucocyte antigen B27; NSAID, non-steroidal anti-inflammatory drug; SIJ, sacroiliac joint; TNFi, tumour necrosis factor inhibitor.