Prevention of new osteitis on magnetic resonance imaging in patients with early axial spondyloarthritis during 3 years of continuous treatment with etanercept: data of the ESTHER trial.

Objective: The aim of this study was to assess the degree of fluctuation of osteitis on MRI during long-term treatment with etanercept (ETN) in patients with early axial SpA (axSpA) with active inflammation (osteitis) on whole-body MRI in the spine and/or the SI joints at baseline.

Methods: We analysed MRI data from 328 SI joint quadrants and 943 spine vertebral units (VUs) in terms of osteitis in the pooled data set of 41 patients who were treated with ETN for 3 consecutive years. Scoring was performed by two blinded radiologists at baseline, year 2 and year 3.

Results: Through years 2 and 3, osteitis on MRI resolved completely in 56 of 144 (38.9%) SI joint quadrants and in 20 of 40 (50%) VUs affected at baseline, while persistent osteitis was found in 24 of 144 (16.7%) SI joint quadrants and in 8 of 40 (20.0%) spine VUs. The development of new osteitis in sites that were free of osteitis at baseline only occurred in 2 of 131 (1.5%) SI joint quadrants and in 3 of 862 (0.4%) spine VUs in both year 2 and year 3.

Conclusion: There was a consistently small amount of osteitis on MRI in patients with early axSpA compared with baseline values, and only a very low rate of new-onset osteitis was found during 3 years of continuous treatment with ETN.

Trial Registration: www.clinicaltrials.gov, NCT00844142.