Purpose: This study evaluated the cost-effectiveness of introducing tofacitinib, an oral Janus kinase inhibitor, to the treatment of Korean patients with rheumatoid arthritis (RA) and an inadequate response to conventional disease-modifying antirheumatic drugs.
Methods: In this cost-utility analysis model, patients transitioned through treatment sequences based on Korean guidelines for RA patients with inadequate response to conventional disease-modifying antirheumatic drugs. Lifetime health-related quality of life and costs were evaluated. Characteristics of the model cohort were based on those reported by the Oral Rheumatoid Arthritis phase 3 triaL (ORAL) Standard randomized Controlled trial of tofacitinib or adalimumab versus placebo. Efficacy was assessed using American College of Rheumatology response rates, converted to the changes in Health Assessment Questionnaire-Disability Index (HAQ-DI) scores, based on tofacitinib clinical trials data. Published clinical trial data on discontinuation rates of the indicated drugs were incorporated in the model. The HAQ-DI scores were mapped onto utility values to calculate outcomes in terms of quality-adjusted life-years (QALYs); HAQ-DI-to-utility (EuroQoL 5D) mapping was based on data from 5 tofacitinib clinical trials. Costs were analyzed from a societal perspective, with values expressed in 2013 Korean won (KRW). Cost-effectiveness is presented in terms of incremental cost-effectiveness ratios (ICERs). One-way sensitivity analyses were performed to assess the robustness of the model.
Findings: First-line tofacitinib used before the standard of care (base-case analysis) increased both treatment costs and QALYs gained versus the standard-of-care treatment sequence, resulting in an ICER of KRW 13,228,910 per QALY. Tofacitinib also increased costs and QALYs gained when incorporated as a second-, third-, or fourth-line therapy. The inclusion of first-line tofacitinib increased the duration of active immunomodulatory therapy from 9.4 to 13.2 years. Tofacitinib-associated increases in costs were attributable to the increased lifetime drug costs. In sensitivity analyses, variations in input parameters and assumptions yielded ICERs in the range of KRW 6,995,719 per QALY to KRW 37,450,109 per QALY.
Implications: From a societal perspective, the inclusion of tofacitinib as a treatment strategy for moderate to severe RA is cost-effective; this conclusion was considered robust based on multiple sensitivity analyses. The study was limited by the lack of clinical data on follow-up therapy after tofacitinib administration and a lack of long-term data on discontinuation of drug use.
Keywords: South Korea; cost-effectiveness; rheumatoid arthritis; tofacitinib.
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