Incremental Costs of Tofacitinib Compared to Adalimumab and Ixekizumab for the Treatment of Active Ankylosing Spondylitis in Denmark

OBJECTIVES: In Denmark, TNF-inhibitors such as adalimumab and IL-17 inhibitors such as ixekizumab are second line treatments for ankylosing spondylitis following lack of effect or intolerance to NSAIDs. As TNF- and IL-17-inhibitors are administered subcutaneously tofacitinib, an oral JAK inhibitor, presents a convenience aspect given its administration form. This study estimates the incremental cost of introducing tofacitinib for ankylosing spondylitis in Denmark, compared to the treatments ixekizumab and adalimumab.

METHODS: Due to the overall comparability of the clinical efficacy (Deodhar et al. 2021 and Dougados et al. 2020), a cost-minimization analysis was performed to estimate the incremental cost pr. patient when comparing tofacitinib to adalimumab and ixekizumab. A limited societal perspective was applied, including drug costs, administration costs, monitoring costs and patient costs. All costs were estimated using a micro-cost approach, and no costs related to adverse events was included. For the base-case analysis an 18 months’ time horizon was used. A discounting rate of 3,5% was used after year 1.

RESULTS: The total costs per patient of treatment with tofacitinib were DKK 104,720, while the total costs per patient of treatment with Ixekizumab were DKK 149,968, giving an incremental cost of DKK -45,248. The total cost per patient for treatment with adalimumab were DKK 91,256, giving an incremental cost of DKK 13,464 compared to tofacitinib. The sensitivity analysis showed that the results found in the base case analysis were fairly robust to change within the investigated parameters.

CONCLUSIONS: Based on list prices, tofacitinib was found to be a cost-saving alternative to ixekizumab but resulted in a slightly higher drug costs than adalimumab. As tofacitinib presents a convenience aspect given its oral administration it could be an attractive alternative to ixekizumab, and for patients who have lost response to or are intolerant to adalimumab or another TNF inhibitor.