Clinical and MRI response to dose reduction of an etanercept-biosimilar for hip arthritis in patients with ankylosing spondylitis: an observational, retrospective cohort study.

OBJECTIVES: Hip arthritis plays a critical role in the prognosis of ankylosing spondylitis (AS). Dose reduction of tumor necrosis factor inhibitors preserves general improvement of AS, so this study attempted to examine the equivalence between Yisaipu® tapering and conventional therapy for hip arthritis in AS patients, using clinical parameters and magnetic resonance image (MRI).

METHODS: AS patients received this etanercept-biosimilar injections (50 mg/week) in the first 12 weeks. Participants in the tapering group were treated with this reagent 50 mg every other week from week 13 to week 24, while the control group kept undergoing full-dose therapy. Clinical and laboratory parameters were assessed at baseline, week 12 and week 24. MRI examination of hip was performed at baseline and week 24.

RESULTS: One hundred and thirty-six patients were enrolled, and 80 of them were in the tapering group. Linear mixed model revealed that main effects of tapering group with control group as reference in disease activity parameters were insignificant (p > 0.05). Main effects of baseline with week 24 as reference were significant (p < 0.05), but main effects of week 12 with week 24 as reference were not (p > 0.05). Prevalence of acute inflammatory change in MRI significantly decreased in the tapering group (76.88% vs 20.00%, p < 0.05) and control group (76.79% vs 19.64%, p < 0.05). Influence of both treatments on acute inflammatory change was equivalent (p > 0.05).

CONCLUSION: Efficacy of Yisaipu® tapering treatment is comparable to the full-dose therapy for hip arthritis in AS patients. Both treatments maintain remission of hip arthritis after patients achieved low disease activity.