Cost-effectiveness of 3 versus 6years of zoledronic acid treatment before bisphosphonate holiday for women with osteoporosis.

Abstract

We compared the effectiveness and cost-effectiveness of cycles of 3years versus 6years of zoledronic acid treatment prior to 3-year bisphosphonate holidays for US postmenopausal women with osteoporosis. We developed an individual-level state-transition microsimulation cost-effectiveness model to compare treatment strategies over the lifetime of recurrent periods of 3years of zoledronic acid followed by 3-year holidays (zoledronic acid 3/3), recurrent periods of 6years of zoledronic acid followed by 3-year holidays (zoledronic acid 6/3), and no zoledronic acid treatment for women with osteoporosis and femoral neck BMD T-scores between - 2.5 and - 3.5. Base-case analysis and all key parameter sensitivity analysis findings for every treatment initiation age evaluated (50, 60, 70, and 80) revealed that zoledronic acid 3/3 was consistently the most cost-effective strategy, assuming a willingness-to-pay of $100,000 per quality-adjusted life-year (QALY). In general, the zoledronic acid 3/3 and 6/3 strategies were relatively close in effectiveness (QALYs) over the lifetime; however, lifetime direct health care costs were on average approximately $2000 lower for the 3/3 strategy. Probabilistic sensitivity analysis results revealed that the zoledronic acid 3/3 strategy was favored in greater than 70% of the iterations for a willingness-to-pay threshold of $100,000/QALY for all treatment initiation ages evaluated. After 3years of zoledronic acid treatment for postmenopausal women with osteoporosis and femoral neck BMD T-scores between - 2.5 and - 3.5, taking 3-year holidays before restarting another treatment cycle is likely to be more cost-effective over the lifetime than cycles of 6years of treatment prior to 3-year holidays.