A microcosting analysis of zoledronic acid and pamidronate therapy in patients with metastatic bone disease

Our goal was to calculate resource use associated with administration of zoledronic acid, compared with pamidronate, as palliative care for patients with metastatic bone lesions. We conducted a time-and-motion study of therapy administration at each of three outpatient chemotherapy infusion sites participating in clinical trials of zoledronic acid and pamidronate. We developed a data-collection instrument to record all staff effort and patient resource use in drug administration. The main outcome measures were (a) direct costs of therapy administration per patient and (b) opportunity benefits expressed as the availability of resources gained per year. The average visit time for patients receiving the study dose of zoledronic acid, 4 mg, was 1 h, 6 min, compared to 2 h, 52 min for patients receiving a 90-mg dose of pamidronate. Infusion time accounted for much of the difference. In the base-case analysis, total direct costs per patient were $728 for zoledronic acid and $776 for pamidronate. The opportunity benefit for infusion of zoledronic acid vs pamidronate in the base case was 1.8 chairs per day, or 426 chairs per 240-workday year. Results were sensitive to changes in infusion facility size, days of operation, and average number of patients treated. Shorter infusion time associated with the administration of zoledronic acid, compared with pamidronate, yields substantial time savings for patients, as well as opportunity benefits for outpatient oncology facilities.