Pamidronate in prevention of bone complications in metastatic breast cancer: a cost-effectiveness analysis

Pamidronate is effective in reducing bony complications in patients with metastatic breast cancer who have known osteolytic lesions. However, pamidronate does not increase survival and is associated with additional financial costs and inconvenience. We conducted a post-hoc evaluation of the cost-effectiveness of pamidronate using the results of two randomized trials that evaluated pamidronate 90 mg administered intravenously every month versus placebo.

The trials differed only in the initial systemic therapy administered (hormonal or chemotherapy). Total skeletal related events (SREs), including surgery for pathologic fracture, radiation for fracture or pain control, conservatively treated pathologic fracture, spinal cord compression, or hypercalcemia, were taken directly from the trials. Using a societal perspective, direct health care costs were assigned to each SRE. Each group's monthly survival was equal and was projected to decline using observed median survivals. The cost of pamidronate reflected the average wholesale price of the drug plus infusion. The value or disutility of an adverse event per month was evaluated using a zero value (events avoided) or an assigned one (range, 0.2 to 0.8).

The cost of pamidronate therapy exceeded the cost savings from prevented adverse events. The difference between the treated and placebo groups was larger with hormonal systemic therapy than with chemotherapy (additional $7,685 compared with $3,968 per woman). The projected net cost per SRE avoided was $3,940 with chemotherapy and $9,390 with hormonal therapy. The cost-effectiveness ratios were $108,200 with chemotherapy and $305, 300 with hormonal therapy per quality-adjusted year.

Although pamidronate is effective in preventing a feared, common adverse outcome in metastatic breast cancer, its use is associated with high incremental costs per adverse event avoided. The analysis is most sensitive to the costs of pamidronate and pathologic fractures that were asymptomatic or treated conservatively.