Comparing tapering strategy to standard dosing regimen of recombinant human tumor necrosis factor receptor-Ig fusion protein for injection in patients with ankylosing spondylitis in low disease activity

Abstract

Objective To compare the effectiveness, safety and costs of standard versus individually tailored reduced doses of recombinant human tumor necrosis factor receptor-Ig fusion protein for injection (rhTNFR:Fc) in patients with ankylosing spondylitis (AS) after achieving low disease activity. Methods This was a single center prospective observational study performed within Renji Hospital. The etanercept biosimiliar (Qiangke) tapering strategy was chosen by treating physicians, without pre-specified protocol. We used pro-pensity score (PS) methodology to identify 2 cohorts of patients matched for relevant baseline characteristics including age, gender, baseline activity, baseline function, disease duration, duration of anti-tumor necrosis factor (TNF) therapy. Multiple clinical indexes including Bath ankylosing spondyliti diseases activity index (BASDAI) and Bath ankylosing spondylitis functional index (BASFI), C reactive protein (CRP) at baseline and every follow up visits and costs of rhTNFR:Fc drugs were compared between both PS-matched cohorts. T test, Mann-Whitney U test, chi-square test were used for statistical analysis. Results One hundred and twenty-seven consecutive AS patients were included who were treated with either reduced (n=72) or standard (n=55) doses of TNF inhibitors. The mean change per 1 year in BASFI, as well as BASDAI and CRP of every visit was not different between both groups, but the cost for anti-TNF drugs was substantially lower in the reduced dosing group [(47 328±5 695) ￥/year vs (84 864±569) ￥/year, t=0.015, P<0.05]. The number of patients with flares was similar in both groups [29% (21/72) vs 21.8% (12/55), χ2=0.88, P=0.347]. Conclusion The strategy to reduce doses of rhTNFR:Fc produce similar clinical outcomes at 1 year in AS patients after reaching low disease activity, but is substantially less costly. Key words: Spondylitis, ankylosing; Comparative effectiveness research; Clinical protocols