Table 2. Associations between osteitis on MRI (in the SI joints and spine) and disease activity at the current time point in patients with axSpA, as determined using multivariable longitudinal generalised estimating equations.

Models	Outcome
	ASDAS current time point,* β (95% CI)	ASDAS current time point,† β (95% CI)
SI joint osteitis score (per one point increase)	0.08 (0.05; 0.11)	0.04 (0.01; 0.08)
SI joint osteitis score (≤1 vs >1)	−0.37 (−0.60; −0.15)	−0.17 (−0.33; −0.01)
Spine osteitis score (per one point increase)	0.06 (0.02; 0.10)	0.01 (−0.04; 0.07)
Spine osteitis score (≤1 vs >1)	−0.19 (−0.44; 0.06)	−0.01 (−0.20; 0.18)

Each model in the multivariable regression analysis was adjusted for sex, age, HLA-B27 positivity, symptom duration, and NSAID intake.

^*All time points independent from treatment were included in this analysis (n=313).

^†Only time points with continuous etanercept (at least 6 months) were included in this analysis (n=186).

ASDAS, Axial Spondyloarthritis Disease Activity Score; axSpA, axial spondyloarthritis; NSAIDnon-steroidal anti-inflammatory drugSI, sacroiliac