Background: In the US, 26 % of women aged ≥65 years, and over 50 % of women aged ≥85 years are affected with postmenopausal osteoporosis (PMO). Each year, the total direct health care costs are estimated to be $US12-18 billion.
Objective: The cost effectiveness of denosumab versus oral bisphosphonates in postmenopausal osteoporotic women from a US third-party payer perspective was evaluated.
Methods: A lifetime cohort Markov model was developed with seven health states: 'well', hip fracture, vertebral fracture, 'other' osteoporotic fracture, post-hip fracture, post-vertebral fracture, and dead. During each cycle, patients could have a fracture, remain healthy, remain in a post-fracture state or die. Relative fracture risk reductions, background fracture risks, mortality rates, treatment-specific persistence rate, utilities, and medical and drug costs were derived using published sources. Expected costs and quality-adjusted life years (QALYs) were estimated for generic alendronate, denosumab, branded risedronate, and branded ibandronate in the overall PMO population and high-risk subgroups: (a) ≥2 of the following risks: >70 years of age, bone mineral density (BMD) T score less than or equal to -3.0, and prevalent vertebral fracture; and (b) ≥75 years of age. Costs and QALYs were discounted at 3 % annually, and all costs were inflated to 2012 US dollars. Sensitivity analyses were conducted by varying parameters e.g., efficacies of interventions, costs, utilities, and the medication persistence ratio.
Results: In the overall PMO population, total lifetime costs for alendronate, denosumab, risedronate, and ibandronate were $US64,400, $US67,400, $US67,600 and $US69,200, respectively. Total QALYs were 8.2804, 8.3155, 8.2735 and 8.2691, respectively. The incremental cost-effectiveness ratio (ICER) for denosumab versus generic alendronate was $US85,100/QALY. Risedronate and ibandronate were dominated by denosumab. In the high-risk subgroup (a), total costs for alendronate, denosumab, risedronate and ibandronate were $US70,400, $US70,800, $US74,000 and $US76,900, respectively. Total QALYs were 7.2006, 7.2497, 7.1969 and 7.1841, respectively. Denosumab had an ICER of $US7,900/QALY versus generic alendronate and dominated all other strategies. Denosumab dominated all strategies in women aged ≥75 years. Base-case results between denosumab and generic alendronate were most sensitive to the relative risk of hip fracture for both drugs and the cost of denosumab.
Conclusion: In each PMO population examined, denosumab represented good value for money compared with branded bisphosphonates. Furthermore, denosumab was either cost effective or dominant compared with generic alendronate in the high-risk subgroups.