Cost-effectiveness of zoledronic acid (ZOL) for the treatment of bone loss in postmenopausal women with early-stage breast cancer receiving aromatase inhibitors in the United States (US).

Abstract

e11007 Background: Treatment guidelines recommend the use of bisphosphonates in postmenopausal women with early-stage breast cancer receiving prolonged aromatase inhibitor therapy and who are at high risk of fractures (e.g., in patients whose bone loss has become clinically significant, e.g., with bone mineral density BMD T score < 2 SD below normal, or who have experienced a fragility fracture). This retrospective modeling analysis assessed the cost-effectiveness of ZOL therapy versus no therapy for the treatment of aromatase inhibitor induced bone loss in US postmenopausal women with breast cancer. Methods: A model was developed to project the lifetime fractures incidence as a function of BMD. In the model, patients were assumed to receive aromatase inhibitors (i.e., letrozole [Femara] 2.5 mg daily), for 5 years with a starting T score of -2 or more. In one arm, patients initiated ZOL (4 mg IV infusion q 6 months) when their BMD T-score decreased to more than 2 SD below normal or had nontraumatic fracture. Data regarding the efficacy of this treatment arm came from the results of the US- based Z-FAST trial. In the comparison group, patients were assumed to receive no ZOL therapy. The progression of bone loss and risk of fracture in the no treatment group were obtained from the published epidemiologic literature. The model simulated the impact of fractures on costs, quality of life and mortality. Results: Compared to the no treatment arm, patients on the ZOL arm experienced a gain of 0.032 quality-adjusted life-years (QALYs), at the incremental costs of $47,995 per QALY. In a sensitivity analysis in which a Medicare payer perspective was adopted, whereby only 80% of costs are included, the costs/QALY improved to $38,396. Conclusions: The use of ZOL for the treatment of aromatase inhibitor induced bone loss in postmenopausal women with breast cancer whose bone loss has become clinically significant or who have experienced a fragility fracture appears cost-effective in the US. These results might be conservative as they exclude the potential benefits of ZOL on disease progression. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Novartis Novartis Novartis Novartis