Biological tapering is cost-effective in patients with inflammatory arthritis in the biosimilar era: secondary analyses on the randomised BIODOPT trial.

Objectives: We assessed the cost-effectiveness of disease activity-guided tapering to continuation of biologics as usual care in inflammatory arthritis. Methods: Adults with rheumatoid arthritis, psoriatic arthritis, or axial spondyloarthritis on stable biological dose (including biosimilars) and in low disease activity ≥12 months were randomised (2:1) to disease activity-guided tapering or continuation of biologics as usual care.The cost-effectiveness evaluation assessed the 18-month quality-adjusted life years (QALYs), hospital costs, and patient costs. Analyses were based on intention-to-treat. Missing short form six-dimensional (SF-6D) values were imputed with the mean SF-6D value in the relevant group at the specific time point. Patients lost to follow-up were assumed to continue their baseline biological dose onwards. We used a 2-sample Results: Of 142 included patients, 78% were treated with biosimilars. At 18 months, 75% (71/95) of the tapering group and 17% (8/47) of the control group were on a tapered biological dose. We found no difference between groups in QALYs, mean difference: 0.008 points (95% CI: -0.008 to 0.024). Patients in the tapering group incurred significantly lower mean hospital costs than the control group, between-group difference: -1936€ (95% CI: -3753€ to -119€). Mean patient costs were comparable between groups: -52€ (95% CI: -350€ to 246€). Conclusions: Disease activity-guided tapering of biologics in a biosimilar era resulted in substantial reductions in 18-month hospital costs, whereas the impact on QALY and patient costs was similar. Thus, the tapering algorithm was cost-saving.