Table 4.

Interaction effects analysis for the Week 12 and Week 52 predictor models

	Week 12				Week 52
Interaction effect	ASDAS-MI	ASAS40	BASDAI50	ASDAS-ID	ASDAS-MI	ASAS40	BASDAI50	ASDAS-ID
MRI*HLA-B27	0.5599	0.8460	0.1517	0.6183	0.0035*	0.0014*	0.0049*	0.0247*
Sex*MRI	0.6680	0.3600	0.6663	0.9666	0.0005*	0.9107	0.1873	0.0030*
Age*MRI	0.8676	0.5666	0.0916	0.2039	0.9140	0.8291	0.4061	0.7247
CRP*MRI	0.8584	0.4112	0.7003	0.0681	0.0626	0.7511	0.7955	0.4636
Sex*CRP	0.7179	0.3568	0.5063	0.8552	0.8904	0.7033	0.6215	0.2282
Age*CRP	0.9958	0.4325	0.0985	0.5441	0.0526	0.3986	0.9907	0.3007

p-values from the final regression step are reported. *Significant interaction terms included in the final model. ASAS40 Assessment of SpondyloArthritis International Society 40%, ASDAS Ankylosing Spondylitis Disease Activity Score, ASDAS-ID ASDAS inactive disease (ASDAS <1.3), ASDAS-MI ASDAS major improvement (reduction in ASDAS ≥2.0), BASDAI50 Bath Ankylosing Spondylitis Disease Activity Index 50%, HLA-B27 human leukocyte antigen-B27, MRI magnetic resonance imaging