PCN73 Cost Effectiveness of Zoledronic Acid vs. Pamidronate or No therapy for the Treatment of Bone Metastases Secondary to Prostate Cancer

Abstract

Zoledronic acid (ZOL) is the only approved bisphosphonate for SRE prevention in hormone-refractory prostate cancer (mHRPC). However, in the UK (UK), 19% and 4% of metastatic, mHRPC patients, do not receive bisphosphonates or receive non-approved/unproven bisphosphonates (i.e., pamidronate [PAM]), respectively for the prevention of skeletal-related events (SREs). This analysis sought to estimate, from a UK payer perspective, the cost effectiveness of providing ZOL to those mHRPC patients not receiving ZOL. This analysis was based on the results of a published randomized phase III clinical trial wherein mHRPC patients received ≤15 months of ZOL or placebo (PBO) (Saad et al, 2002). Since PAM has been shown to be no different than PBO in mHRPC in a pooled analysis of two trials (Small et al 2003) (i.e., 25% of subjects experienced an SRE at 6 months), the PBO cohort data from the ZOL trial was as a surrogate for PAM data in the absence of a direct comparison of ZOL versus PAM (or other bisphosphonates). Costs were estimated using hospital tariffs and published/internet sources. Quality adjusted life years (QALYs) gained were based on a previously published analysis of the Saad et al (2002) data. Survival was assumed to be identical for both groups. Compared with the use of PAM/PBO, treatment with ZOL (at list price of £174.14/infusion vs £80/infusion with PAM) resulted in increased QALYs (+0.03566/pt), fewer SREs (-0.8314/pt, i.e., 0.8315 vs 1.6629), and fewer SRE-related costs (-£1,639/pt, i.e., £2,004 vs. £3,643). Total costs were higher with ZOL (+£702/pt). ZOL cost £19,689/QALY. The use of ZOL for the prevention of SREs in UK patients with bone metastases secondary to mHRPC is cost effective relative to providing no or unapproved bisphosphonates.