Two-year cost effectiveness between two gradual tapering strategies in rheumatoid arthritis: cost-utility analysis of the TARA trial

OBJECTIVE: The aim of the current study was to evaluate the 2-year cost-utility ratio between tapering conventional synthetic disease-modifying antirheumatic drugs (csDMARD) first followed by the tumour necrosis factor (TNF)-inhibitor, or vice versa, in patients with rheumatoid arthritis (RA). METHODS: Two-year data of the Tapering strategies in Rheumatoid Arthritis trial were used. Patients with RA, who used both a csDMARD and a TNF-inhibitor and had a well-controlled disease (disease activity score ≤2.4 and swollen joint count≤1) for at least 3 months, were randomised into gradual tapering the csDMARD first followed by the TNF-inhibitor, or vice versa. Quality-adjusted life years (QALYs) were derived from the European Quality of life questionnaire with 5 dimensions. Healthcare and productivity costs were calculated with data from patient records and questionnaires. The incremental cost-effectiveness ratio and the incremental net monetary benefit were used to assess cost effectiveness between both tapering strategies. RESULTS: 94 patients started tapering their TNF-inhibitor first, while the other 95 tapered their csDMARD first. QALYs (SD) were, respectively, 1.64 (0.22) and 1.65 (0.22). Medication costs were significantly lower in the patients who tapered the TNF-inhibitor first, while indirect cost were higher due to more productivity loss (p=0.10). Therefore, total costs (SD) were €38 833 (€39 616) for tapering csDMARDs first, and €39 442 (€47 271) for tapering the TNF-inhibitor (p=0.88). For willingness-to-pay (WTP) levels <€83 800 tapering, the csDMARD first has the highest probability of being cost effective, while for WTP levels >€83 800 tapering the TNF-inhibitor first has the highest probability. CONCLUSION: Our economic evaluation shows that costs are similar for both tapering strategies. Regardless of the WTP, tapering either the TNF-inhibitor or the csDMARD first is equally cost effective. TRIAL REGISTRATION NUMBER: NTR2754.