PCN8 COST-EFFECTIVENESS ANALYSIS OF ORAL IBANDRONATE VERSUS IV ZOLEDRONIC ACID OR IV GENERIC PAMIDRONATE FOR BONE METASTASES FROM BREAST CANCER IN PATIENTS RECEIVING ORAL HORMONAL THERAPY IN THE UK

Abstract

OBJECTIVES: Oral ibandronate (ibandronic acid) is a bisphosphonate approved in the UK for treatment of bone metastases from breast cancer. Administration of oral ibandronate oncedaily can be easily combined with oral hormonal therapy, saving costs of iv bisphosphonate administration and monitoring. We used cost-effectiveness (C/E) modelling to compare oral ibandronate with iv zoledronic acid or iv generic pamidronate in this setting. METHODS: The model assumed a UK NHS perspective with a duration of 14.3 months (expected average survival). Patients were assumed to receive oral hormonal therapy for 53% of their survival. Primary outcomes were direct Health Care costs and QALYs. Resource use data for iv bisphosphonates came from a published micro-costing study (validated through review by a UK clinician); costs were calculated using a unit cost database. Monthly drug acquisition costs were £195 for oral ibandronate and iv zoledronic acid, and £165 for iv generic pamidronate. The cost of managing skeletal-related events (SREs) came from a published study. Renal adverse events with monitoring and treatment costs were assumed for zoledonic acid. Efficacy was calculated as the relative risk reduction (RR) of SREs; utility scores were applied to time with/without an SRE (SRE duration assumed 1 month). RESULTS: The projected total cost was £297 less/patient with oral ibandronate than with zoledronic acid, and £1087 less than with generic pamidronate. Oral ibandronate led to a gain of 0.02 QALYs (due to SRE RR and bone pain relief), making it the economically dominant treatment option. For completeness, C/E results for iv ibandronate will also be presented, demonstrating C/E. CONCLUSIONS: This study demonstrated the use of C/E modelling to compare oral versus iv bisphosphonates using published data validated by expert clinician review. Oral ibandronate was found to be cost-effective for the management of bone metastases from breast cancer in patients receiving oral hormonal therapy.