The real-world cost-effectiveness of adjuvant trastuzumab in HER-2/neu-positive early breast cancer in Taiwan

Background: Trastuzumab was considered a cost-effective adjuvant treatment for HER 2-positive early breast cancer. Since 2010, the Taiwanese National Health Insurance (NHI) has started to reimburse for 1-year adjuvant treatment. This study aims to provide an updated cost-effectiveness analysis from the NHI perspective, which explores assumptions about long-term cardiac toxicity and treatment benefit of 1-year adjuvant treatment sequentially after chemotherapy. Methods: A Markov model was used to evaluate the cost-effectiveness of 1-year adjuvant trastuzumab for HER-2/neu positive early breast cancer over a 20-year life-time horizon. A probability sensitivity analysis using Monte Carlo simulation was performed to characterize uncertainties in the expected outcomes, which are expressed as an incremental costs effectiveness ratio (ICER, cost/QALY). A willingness-to-pay threshold of 3-times the per capita gross domestic product was adopted according to the WHO definition. The Taiwan per capita gross domestic product in 2015 was US$22,355; thus, a threshold was considered as NT$2,011,950 (US$67 065, 1USD =30 NTD in 2015). Results: The model showed that adjuvant trastuzumab treatment in HER-2/neu positive early breast cancer yielded 1.631 quality-adjusted life-years (QALY) compared with no trastuzumab treatment. The ICER was US $51,863 per QALY gained in the base-case scenario. The Monte Carlo simulation by varying all variables simultaneously demonstrated that the probability of cost-effectiveness at the willingness-to-pay threshold of US$67,065 was 50% for 1-year adjuvant trastuzumab. Conclusions: From this real-world study, 1-year adjuvant trastuzumab treatment is likely to be a cost-effective therapy for patients with HER-2 positive breast cancer at the willingness-to-pay threshold of 3-times GDP per capita in Taiwan.