Table 3 Linear regression modelling of the associations between biomarker levels (baseline and percentage change from baseline to week 2 or week 24) and change from baseline to week 24 in disease activity (BASDAI) and the spinal inflammation detected by MRI (MRI activity score)

Model	r2	b	p Value
Infliximab group
MRI activity score: change from baseline to week 24
Baseline biomarker levels
no parameters significantly associated	−	−	−
Percentage change from baseline to week 2 in biomarker levels	0.011
IL-6		0.053	<0.001
Percentage change from baseline to week 24 in biomarker levels	0.042
CRP		0.009	0.009
BASDAI: change from baseline to week 24
Baseline biomarker levels	0.043
CRP		−0.196	0.005
Percentage change from baseline to week 2 in biomarker levels	0.099
IL-6		0.021	<0.001
Percentage change from baseline to week 24 in biomarker levels	0.113
VEGF		0.005	0.029
CRP		0.005	0.005
Placebo group
No biomarker levels at baseline or changes from baseline to week 2 or 24 were significantly associated with changes in MRI activity score or BASDAI at week 24

BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CRP, C-reactive protein; IL-6, interleukin-6; MRI, magnetic resonance imaging; VEGF, vascular endothelial growth factor.