Hospital visits among women with skeletal-related events secondary to breast cancer and bone metastases: a nationwide population-based cohort study in Denmark

Marie Louise Svendsen,¹ Henrik Gammelager,¹ Claus Sværke,¹ Mellissa Yong,² Victoria M Chia,² Christian F Christiansen,¹ Jon P Fryzek<sup>1

1</sup>Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; ²Center for Observational Research, Amgen, Thousand Oaks, CA, USA

Objective: Skeletal-related events (SREs) among women with breast cancer may be associated with considerable use of health-care resources. We characterized inpatient and outpatient hospital visits in a national population-based cohort of Danish women with SREs secondary to breast cancer and bone metastases.
Methods: We identified first-time breast cancer patients with bone metastases from 2003 through 2009 who had a subsequent SRE (defined as pathologic fracture, spinal cord compression, radiation therapy, or surgery to bone). Hospital visits included the number of inpatient hospitalizations, length of stay, number of hospital outpatient clinic visits, and emergency room visits. The number of hospital visits was assessed for a pre-SRE period (90 days prior to the diagnostic period), a diagnostic period (14 days prior to the SRE), and a post-SRE period (90 days after the SRE). Patients who experienced more than one SRE during the 90-day post-SRE period were defined as having multiple SREs and were followed until 90 days after the last SRE.
Results: We identified 569 women with SREs secondary to breast cancer with bone metastases. The majority of women had multiple SREs (73.1%). A total of 20.9% and 33.4% of women with single and multiple SREs died in the post-SRE period, respectively. SREs were associated with a large number of hospital visits in the diagnostic period, irrespective of the number and type of SREs. Women with multiple SREs generally had a higher number of visits compared to those with a single SRE in the post-SRE period, eg, median length of hospitalization was 5 days (interquartile range 0–15) for women with a single SRE and 13 days (interquartile range 4–30) for women with multiple SREs.
Conclusion: SREs secondary to breast cancer and bone metastases were associated with substantial use of hospital resources.

Keywords: breast neoplasms, bone metastases, skeletal-related events, hospital services, utilization