Cost-effectiveness of zoledronic acid for the prevention of skeletal complications in patients with prostate cancer

Purpose: We estimated the cost-effectiveness of zoledronic acid vs placebo for decreasing skeletal complications in men with prostate cancer. Materials and Methods: We performed a cost-effectiveness analysis alongside a multinational clinical trial of zoledronic acid. Cost estimation was based on prospectively collected resource use data for 85.3% of enrolled patients. Cost-effectiveness ratios were based on within-trial data on clinical outcomes, quality of life and study medication cost. Results: Patients receiving zoledronic acid experienced fewer hospital days during a mean followup of 9 months (average 5.6 vs 8.0 days; p=0.1910). Mean direct costs excluding study medication were $5,365 for patients receiving zoledronic acid and $5,689 for patients receiving placebo, a difference of $324 (95% CI $1,781 to $1,146). The global average cost of zoledronic acid plus its administration during the trial was $5,677 ($450 per dose). The nominal cost per skeletal complication avoided was $12,300 (95% CI $6,900 to $48,700) and the cost per additional patient free of skeletal complications was $51,400 (95% CI $26,900 to $243,700). Nominal within-trial cost per quality adjusted life-year was $159,200, which varied widely in sensitivity analyses. Conclusions: The nominal base case estimate of the cost per quality adjusted life-year for zoledronic acid in the prevention of skeletal complications of prostate cancer is consistent with that of bisphosphonates in breast cancer. However, the cost-effectiveness ratios for bisphosphonates are higher than commonly cited thresholds for conferring cost-effectiveness.