The Clinical and Economic Impacts of Skeletal-Related Events Among Medicare Enrollees With Prostate Cancer Metastatic to Bone

Background: Approximately 40% of men diagnosed with metastatic prostate cancer experience one or more skeletal-related events (SREs), defined as a pathological fracture, spinal cord compression, or surgery or radiotherapy to the bone. Accurate assessment of their effect on survival, health care resource utilization (HCRU), and cost may elucidate the value of interventions to prevent SREs.

Materials and methods: Men older than age 65 years with prostate cancer and bone metastasis diagnosed between 2004 and 2009 were identified from linked Surveillance Epidemiology and End Results-Medicare records. Hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk for death associated with SREs were calculated by using Cox regression. HCRU and costs (in 2013 U.S. dollars) were evaluated in a propensity score-matched cohort by using Poisson regression and Kaplan-Meier sample average estimators, respectively.

Results: Among 3,297 men with prostate cancer metastatic to bone, 40% experienced ≥1 SRE (median follow-up, 19 months). Compared with men who remained SRE-free, men with ≥1 SRE had a twofold higher risk for death (HR, 2.29; 95% CI, 2.09-2.51). Pathological fracture was associated with the highest risk for death (HR, 2.77; 95% CI, 2.38-3.23). Among men with ≥1 SRE, emergency department visits were twice as frequent (95% CI, 1.77-2.28) and hospitalizations were nearly four times as frequent (95% CI, 3.20-4.40). The attributable cost of ≥1 SRE was $21,191 (≥1 SRE: $72,454 [95% CI, $67,362-$76,958]; SRE-free: $51,263 [95% CI, $45,439-$56,100]).

Conclusion: Among men with prostate cancer metastatic to bone, experiencing ≥1 SRE is associated with poorer survival, increased HCRU, and increased costs. These negative effects emphasize the importance of SRE prevention in this population.