Incremental cost (IC) analysis of skeletal related events (SREs) among elderly men with stage IV metastatic (M1) prostate cancer (PCa).

Abstract

e16034 Background: Patients diagnosed with stage IV M1PCa are predisposed to SREs, such as pathologic fracture (PF), spinal cord compression (SCC) and bone surgery (BS). There is limited information in the literature regarding the ICs associated with SREs among stage IV M1 PCa patients. Methods: We analyzed patients aged 66+ yrs diagnosed with incident stage IV M1 PCa between 2000 and 2007 from the linked SEER-Medicare dataset. Five mutually exclusive SRE categories were created: PF only, PF+concurrent surgery (SRG), SCC only, SCC+SRG, and BS only. Patients with multiple SREs were excluded. A propensity score for the incidence of an SRE was estimated using a logistic regression model including baseline demographic and clinical variables, diagnosis year and SEER region. Patients with SREs (cases) were matched to those without SREs (controls), based on the propensity score. The date of SRE of a case was assigned to a matched control, and the 12 month pre- and post-SRE costs were calculated. A difference-in-difference method was used to estimate the ICs (post-pre) for cases vs. controls. The analysis was conducted from a US Medicare perspective. Results: Application of inclusion criteria resulted in 1,131 stage IV M1 PCa patients with SREs. The average age was 78 yrs and 12% were African American. Using the propensity score, 1,031 cases were matched with 1,031 controls and allocated to the following SRE groups: PF+SRG (n=134), PF only (n=143), SCC+SRG (n=40), SCC only (n=538) and BS only (n=176). The average IC per SRE was $30,548 (vs. controls). The most expensive SRE group was SCC+SRG with a total average IC of $62,412, followed by BS only ($37,554), PF+SRG ($35,520), SCC ($28,027), and PF only ($17,839). Inpatient costs were the major driver of ICs followed by physician/non-institutional provider and skilled nursing facility (SNF) costs. Conclusions: The ICs associated with an SRE are significant. The IC of an SRE varies by type of SRE and service category. [Table: see text]