Economic value of zoledronic acid compared with placebo in the treatment of skeletal metastases in patients with solid tumors: The case of the United Kingdom (UK)

Abstract

6603 Background: Zoledronic acid (ZA) reduces the risk of skeletal-related events (SREs) in patients with solid tumors (i.e., renal cell carcinoma, thyroid, head and neck, small cell lung, or others cancers, excluding breast, prostate and non small cell lung [NSCLC] cancers) and bone metastases. This analysis assessed, from the perspective of the UK National Health Service, the economic impact of ZA in this patient population. Methods: A literature-based decision-analytic model was developed to compare the direct costs and quality adjusted life years (QALY) of patients with bone metastases secondary to solid tumors receiving ZA or placebo. Survival, SRE incidence, and number of infusions administered were obtained from a clinical trial comparing patients randomized to 4 mg ZA or placebo for up to 21 months. Drug acquisition and administration costs and SRE costs were estimated using published sources and national fee schedules (e.g., NHS reference costs, British National Formulary). The impact of SREs on quality of life was estimated using the literature. Consistent with previous economic analyses of bisphosphonates in cancers (e.g., Hillner et al, 2000), patients were assumed to experience quality of life improvements lasting 1 month for each SRE avoided. Results: The average remaining life expectancy was conservatively assumed equal in both groups and was 9.54 months (median, 6.61 months). Patients receiving placebo were projected to experience 2.64 SREs on average v. 1.64 SREs among ZA patients. QALYs were estimated at 0.3917 per patient (pp) and 0.3728 pp in the ZA and placebo groups, respectively. ZA drug- related costs were estimated at £1,386 pp, based on an average of 5.52 infusions pp. The use of ZA was associated with a reduction of £1,830 pp in SRE costs. Overall, ZA saved costs and increased QALYs v. no therapy, by £445 pp and 0.0189 QALYs pp, respectively. In sensitivity analyses, ZA cost £25,000 or less per QALY under a wide range of assumptions. Conclusions: The use of ZA leads to fewer SREs, better estimated quality of life, and lower costs relative to placebo in UK patients with bone metastases secondary to solid tumors other than breast, prostate or NSCLC cancer. ZA appears therefore highly cost effective in this population. No significant financial relationships to disclose.