Background Patients with advanced solid tumours commonly develop bone metastases. Development of skeletal related events (SREs) is associated with higher mortality and increased treatment costs. Incidence and time to onset of SREs are widely used as composite endpoints in clinical trials. Intravenous bisphosphonates, predominantly zoledronic acid (ZA), and denosumab, are effective in preventing SREs. ZA is associated with renal failure, and dose reductions are requested based on creatinine clearance.

Purpose The aim of the study was to define the most cost effective treatment between ZA and denosumab by a budget impact analysis with a 3 year horizon.

Material and methods A database was created using data extracted from electronic medical records and all prescriptions filed during the period January 2015 to September 2016 (2638 prescriptions). Variations in drug prices were analysed. A pharmaceutical and budget impact analysis were conducted. Potential budget impact was assessed based on drug purchase prices, drug administration costs, and SREs incidence (Lipton 2012) and management (Cavallo 2014). Previous clinical trials showed that denosumab was superior to ZA in preventing SREs in patients with bones metastases (−17%).

Results ZA was more frequently prescribed than denosumab (21.5%). Denosumab related costs were superior to the savings associated with a lower incidence of SREs. The analysis estimated a target price for denosumab to be economically competitive with ZA (−47.7%). In several cases, ZA was not indicated. Limiting the use of denosumab to patients who are not eligible for ZA (ie, those with serious renal failure (6%)) would result in a saving of €51 632,55 over 3 years. Considering also those patients with moderate renal failure (12.5%) who are eligible for denosumab, the saving would be €186 7136 over 3 years. This is negligible compared with the costs related to possible renal complications and a greater incidence of SREs. A sensitivity analysis was also performed that confirmed these results.

Conclusion Based on our hospital purchase prices, ZA offers superior cost effectiveness compared with denosumab, even considering SRE related savings. Treatment with Denosumab has to be limited to patients with serious and moderate renal failure.

References and/or acknowledgements Special thanks to Sarah J Liptrott.

No conflict of interest