The Economic Burden of Skeletal-Related Events Among Elderly Men with Metastatic Prostate Cancer

Abstract

Advanced prostate cancer patients with bone metastasis are predisposed to skeletal complications termed skeletal-related events (SREs). There is limited information available on Medicare costs associated with treating SREs. The objective of this study was to ascertain SRE-related costs among older men with metastatic prostate cancer in the US. We analysed patients aged 66years or older who were diagnosed with incident stage IV (M1) prostate cancer between 2000 and 2007 from the linked Surveillance, Epidemiology and End Results (SEER)-Medicare dataset. A propensity score for the incidence of an SRE was estimated using a logistic regression model including demographic and clinical baseline variables. Patients with SREs (cases) were matched to patients without SREs (controls) based on the propensity score, length of follow-up (i.e. date of prostate cancer diagnosis to last date of observation) and death. Health resource utilization cost differences between cases and controls over time were compared using generalized linear models. Healthcare costs were examined by type of SRE (pathological fracture only, pathological fracture with concurrent surgery, spinal cord compression only, spinal cord compression with concurrent surgery, and bone surgery only) and by source of care (inpatient, physician/non-institutional provider, skilled nursing facility, outpatient and hospice). All costs were adjusted to 2009 US dollars, using the medical care component of the Consumer Price Index. Application of the inclusion criteria resulted in 1,131 metastatic prostate cancer patients with SREs and 6,067 patients without SREs during follow-up. The average age of the sample was 79years, and 14% were African American. A total of 928 patients with SREs were matched to 928 patients without SREs. The average health care utilization cost of patients with SREs was US$29,696 (95% confidence interval [CI] US$24,730-US$34,662) higher than that of the controls. The most expensive SRE group was spinal cord compression with concurrent surgery (US$82,868: 95% CI US$67,472-US$98,264) followed by bone surgery only (US$37,496: 95% CI US$29,684-US$45,308), pathological fracture with concurrent surgery (US$34,169: 95% CI US$25,837-US$ 42,501), spinal cord compression only (US$25,793: 95% CI US$20,933-US$30,653) and pathological fracture only (US$14,649: 95% CI US$6,537-US$22,761). The largest cost difference by source of care was observed for hospitalizations (p<0.01). Metastatic prostate cancer patients with SREs incur higher costs compared to similar patients without SREs. SRE costs among older stage IV (M1) prostate cancer patients vary by SRE type, with spinal cord compression and concurrent surgery costing at least twice as much as other SREs.