Economic evaluation of clodronate and zoledronate in patients diagnosed with metastatic bone disease from the perspective of public and third party payors in Brazil

Abstract

Background: Metastatic bone disease (MBD) is responsible for >99% of malignant tumors that affect the bone. MBD patients have increased risk of skeletal complications that are often dramatic and result in loss of function or disability, leading to rapid deterioration of quality of life. Bisphosphonates have become the standard therapy for the treatment and prevention of skeletal-related events (SREs).

Objective: The objective of this study was to evaluate the cost-effectiveness of zoledronate and clodronate in the prevention of SREs in patients with MBD.

Methods: A pharmacoeconomic analysis was performed for a hypothetical cohort of patients with MBD to compare the costs and consequences of the use of clodronate and zoledronate for treatment and prevention of SREs in MBD in Brazil. The model was constructed using decision analysis techniques. Costs were described in 5 categories-drugs, physician visits, hospitalizations, surgical/medical care, and laboratory tests-and were reported in 2008 Brazilian reais (1 BRL = 0.54 US dollar). Quality-adjusted life years gained was considered as an outcome. Sensitivity analyses tested model robustness.

Results: The total cost of treatment of MBD in Brazil for a 5-year time-horizon was R$46,313 with clodronate and R$50,319 with zoledronate. The estimated number of quality-adjusted life years was 2.00 and 1.90 for clodronate and zoledronate, respectively. Cost-effectiveness ranking was unchanged when model time-horizon was changed to 1 or 10 years. Univariate analysis revealed the incidence of osteonecrosis as a sensitive parameter in the model. Multivariate analysis confirmed base-case results, in which >60% of model iterations favored clodronate over zoledronate.

Conclusion: The present pharmacoeconomic evaluation, under the premises presented, found that clodronate was dominant over zoledronate from both the public and the private health care perspectives in Brazil.