Reviewing the cost-effectiveness of endocrine early breast cancer therapies: influence of differences in modeling methods on outcomes

OBJECTIVES: The purpose of this systematic review is primarily to identify published cost-effectiveness analyses and cost-utility analyses of endocrine therapies for the treatment of early breast cancer. A secondary objective is to identify whether differences in seven modeling characteristics are related to differences in outcome of these cost-effectiveness and cost-utility analyses. METHODS: A systematic literature review was conducted to identify peer-reviewed full economic evaluations of endocrine treatments of early breast cancer published in the English language between 2000 and December 2010. Information from these publications was abstracted regarding outcome, quality, and modeling methods. RESULTS: We identified 20 economic evaluations comprising 5 different endocrine therapeutic strategies, which are all assessed more then once. The incremental cost-effectiveness ratios (ICERs) of the reported outcomes varied widely for identical therapies. For anastrazole compared to tamoxifen, incremental life-years gained even ranged from 0.16 to 0.550 with an ICER ranging from euro3,958 to euro75,331. Incremental quality-adjusted life-years (QALYs) gained ranged from 0.092 to 0.378 with a cost per QALY gained varying from euro3,696 to euro120,265. These large differences in outcome were related to different modeling methods, with differences in time horizon and use of a carryover effect as most prominent causes. CONCLUSION: Despite similar comparators and logical differences due to transferability issues, the outcomes of the included studies varied widely. To increase comparability and transparency of pharmacoeconomic evaluations, standardization of modeling methods for different therapeutic groups/diseases and the availability of a detailed and complete description of the model used in the evaluation is advocated. Recommendations for standardization in modeling treatment strategies in early breast cancer are presented.