Association between resolution of MRI-detected inflammation and improved clinical outcomes in axial spondyloarthritis under long-term anti-TNF therapy.

Objectives: In this post-hoc analysis of ESTHER trial, we aimed to investigate the longitudinal relationship between inflammation on MRI and the achievement of inactive disease/low disease activity in patients with axial spondyloarthritis (axSpA) treated with long-term tumor necrosis factor (TNF) inhibitor etanercept.

Methods: Of the 76 patients with active axSpA in the ESTHER trial, we included all patients treated with etanercept for at least 6 months for main analysis. All clinical and MRI data from 4.5 years of follow-up were used in the analysis. MRIs of the spine and sacroiliac (SI) joints were performed at baseline, week 24, week 48 and yearly thereafter and were evaluated for active inflammatory lesions according to the Berlin MRI score.

Results: Longitudinal analysis showed that higher SI joint osteitis score was associated with higher Axial Spondyloarthritis Disease Activity Score (ASDAS) at the same time point (β=0.08, 95% CI (0.05; 0.11)) and at the next time point 6 months later (β=0.05, 95% CI (0.02; 0.07)). Furthermore, resolution of osteitis in the SI joint (Berlin MRI osteitis score of ≤1) was associated with lower ASDAS at the next time point (β=-0.26, 95% CI (-0.42; -0.09)), higher odds of achieving ASDAS low disease activity (OR=5.61, 95% CI (1.06; 29.67)) and inactive disease status (OR=2.23, 95% CI (1.01; 4.94)) at the next time point.

Conclusions: The presence of inflammation on SI joints-MRI is associated with higher disease activity in axSpA. Resolution of inflammation on MRI is associated with better clinical outcomes in the long-term follow-up. Thus, achieving complete resolution of inflammation is favourable for meeting the treatment goals in axSpA.

Trial Registration Number: NCT00844142.