Candidate for the Lee B. Lusted Student Prize Competition
To ascertain the incremental health care costs associated with the treatment of skeletal related events (SREs), controlling for possible selection biases in the non-randomized comparison of costs between patients with and without SREs among older metastatic prostate cancer (PCa) patients.
Method:
We analyzed patients aged 66 years or older, diagnosed with incident stage IV metastatic PCa between 2000 and 2007 from the linked SEER-Medicare dataset. Five mutually exclusive SRE categories were created for pathologic fracture only (PF), pathologic fracture with concurrent surgery (PF+BS), spinal cord compression only (SCC), spinal cord compression with concurrent surgery (SCC+BS) and bone surgery (BS) only. 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, date of diagnosis, last observation date and death. The SRE diagnosis date of a case was assigned as the index date of the matched control. The difference in costs between cases and controls (i.e. incremental costs) were calculated for the 12 month pre- and post-index periods. Difference-in-difference (DID) estimates were derived to represent the average pre-post incremental cost difference by type of SRE. A sensitivity analysis was carried out for 3-month and 6-month pre-post cost differences. A subgroup analysis was conducted among SRE cases with a bone metastasis diagnosis. The analysis was conducted from a US Medicare perspective.
Result:
Application of the inclusion criteria resulted in 1,131 stage IV metastatic PCa patients with single SREs and 6,067 patients without SREs during follow-up. The average age of the sample was 78.5 years and 14% were African American. A total of 928 patients with SREs were matched to 928 patients without SREs. The DID cost estimate per SRE was $24,329 (95%CI: $21,010- $27,648). The most expensive SRE group was SCC+BS ($68,894: CI $56,431-$56,431) followed by BS only ($30,888: 95%CI $24,570- $37,206), PF+BS ($28,142: 95%CI $21,392- $34,892), SCC only ($21,626: 95%CI $17,718- $25,534) and PF only ($12,219: 95%CI $5,659- $18,780).
Conclusion:
The average health care utilization cost for patients with SREs was $24,329 higher than for stage IV metastatic patients without SREs. The analysis suggests that treatment and procedures to prevent SREs have the potential to yield cost offsets.
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