Association of r22axSpA or r3+axSpA with BASDAI50 response after 1 year of treatment with a first tumour necrosis factor inhibitor in univariable models and a multivariable analysis
| Model | Type of analysis | N | Key variable | OR | 95% CI | P value |
| Model 1 | Univariable | 203 | r22axSpA versus nr-axSpA | 1.22 | 0.67 to 2.21 | 0.57 |
| Model 2 | Univariable | 394 | r3+axSpA versus nr-axSpA | 1.69 | 1.06 to 2.70 | 0.03 |
| Model 3 | Multivariable* | 351 | r22axSpA versus nr-axSpA | 1.28 | 0.59 to 2.77 | 0.54 |
| r3+axSpA versus nr-axSpA | 2.05 | 1.09 to 3.91 | 0.03 |
*Model including the variables age, diagnostic delay, sex, human leucocyte antigen-B27, presence of elevated C reactive protein level, presence of peripheral arthritis, presence of enthesitis, current smoking, Bath Ankylosing Spondylitis Functional Index and Bath Ankylosing Spondylitis Mobility Index, respectively, treatment with etanercept versus treatment with monoclonal antitumour necrosis factor antibodies, body mass index (>30 vs <25 and 25–30 vs <25, respectively). The full model is presented in online supplemental table S4.
r3+axSpA, unilateral/bilateral grade 3–4 radiographic sacroiliitis; r22axSpA, bilateral grade 2 sacroiliitis.