Utilities associated with subcutaneous injections and intravenous infusions for treatment of patients with bone metastases

Louis S Matza,¹ Ze Cong,² Karen Chung,² Alison Stopeck,³ Katia Tonkin,⁴ Janet Brown,⁵ Ada Braun,² Kate Van Brunt,⁶ Kelly McDaniel<sup>1

1</sup>Outcomes Research, United BioSource Corporation, Bethesda, MD, USA; ²Amgen, Inc, Thousand Oaks, CA, USA; ³Department of Medicine, University of Arizona, Tucson, AZ, USA; ⁴Department of Oncology, University of Alberta, Edmonton, Alberta, Canada; ⁵Leeds Institute of Molecular Medicine, St James University Hospital, Leeds, UK; ⁶formerly with Outcomes Research, United BioSource Corporation, Bethesda, MD, USA

Introduction: Although cost-utility models are often used to estimate the value of treatments for metastatic cancer, limited information is available on the utility of common treatment modalities. Bisphosphonate treatment for bone metastases is frequently administered via intravenous infusion, while a newer treatment is administered as a subcutaneous injection. This study estimated the impact of these treatment modalities on health state preference.
Methods: Participants from the UK general population completed time trade-off interviews to assess the utility of health state vignettes. Respondents first rated a health state representing cancer with bone metastases. Subsequent health states added descriptions of treatment modalities (ie, injection or infusion) to this basic health state. The two treatment modalities were presented with and without chemotherapy, and infusion characteristics were varied by duration (30 minutes or 2 hours) and renal monitoring.
Results: A total of 121 participants completed the interviews (52.1% female, 76.9% white). Cancer with bone metastases had a mean utility of 0.40 on a standard utility scale (1 = full health; 0 = dead). The injection, 30-minute infusion, and 2-hour infusion had mean disutilities of −0.004, −0.02, and −0.04, respectively. The mean disutility of the 30-minute infusion was greater with renal monitoring than without. Chemotherapy was associated with substantial disutility (−0.17). When added to health states with chemotherapy, the mean disutilities of injection, 30-minute infusion, and 2-hour infusion were −0.02, −0.03, and −0.04, respectively. The disutility associated with injection was significantly lower than the disutility of the 30-minute and 2-hour infusions (P < 0.05), regardless of chemotherapy status.
Conclusion: Respondents perceived an inconvenience with each type of treatment modality, but injections were preferred over infusions. The resulting utilities may be used in cost-utility models examining the value of treatments for the prevention of skeletal-related events in patients with bone metastases.

Keywords: skeletal-related event, infusion, injection