Retrospective study of the effect of skeletal complications on total medical care costs in patients with bone metastases of breast cancer seen in typical clinical practice.

Intravenous bisphosphonates are effective in reducing the incidence of skeletal-related events (SREs) in women with bone metastases of breast cancer. The cost-effectiveness of such therapy depends in part on the potential cost savings achieved by preventing these events. However, estimates of the costs of SREs in women with bone metastases of breast cancer in typical US clinical practice are unavailable. The purpose of this study was to estimate the treatment costs of clinically significant SREs and the impact of these events on total medical care costs in patients with bone metastases of breast cancer. Data were gathered from a large US health insurance claims database. Patients with bone metastases of breast cancer who experienced one or more clinically significant SREs in typical clinical practice were matched to similar patients without SREs based on propensity scores. Kaplan-Meier estimated total medical care costs were compared over 60 months for propensity-matched samples of patients with SREs and without SREs. We identified 617 patients with breast cancer and bone metastases, including 321 (52%) with > or = 1 clinically significant SRE. After matching, there were 201 patients each in the SRE and no-SRE groups, with mean follow-up of 13.8 and 11.0 months, respectively. In the SRE group, costs of treatment of SREs were $13,940 (95% CI, $11,240-$16,856) per patient. Total medical care costs were $48,173 (95% CI, $19,068-$77,684) greater in SRE versus no-SRE patients (P = 0.001). The costs of clinically significant SREs in patients with breast cancer and bone metastases seen in typical clinical practice are substantial. Treatments that reduce the incidence of SREs, such as intravenous bisphosphonates, should reduce these costs.