Comprehensive investigation of adverse event (AE)-related costs in patients with metastatic breast cancer (MBC) treated with first- and second-line chemotherapies.

Abstract

1037 Background: MBC is incurable and managed with ongoing therapy. This study examined the incremental costs of chemotherapy-associated AEs in MBC. Methods: The PharMetrics Integrated Database (2000-2010) was used to identify MBC pts treated either 1st or 2nd line with a taxane (T) (paclitaxel or docetaxel) or capecitabine (C)-based regimen for ≥30 days (defined as a treatment episode (TE)). Incremental costs attributable to AEs were assessed by comparing costs incurred during TEs with and without AEs. AEs were identified using medical claims with a diagnosis for ≥1 event of interest (e.g., infections, fatigue, anemia, neutropenia). Pt characteristics were balanced between comparison groups (with and w/o AEs) using inverse probability weighting method. Incremental monthly costs due to AEs were estimated during the TEs and included the following cost components: inpt (IP), outpt (OP), emergency room (ER), other medical service, pharmacy costs (chemotherapy and other drugs), and total healthcare costs. Statistical comparisons were conducted using Wilcoxon tests. Results: 3,222 women (mean age=57) received a T or C as 1st or 2nd-line therapy for MBC. Of the 2,678 1st-line pts, 69.7% received T and 30.3% with C; average monthly total costs ranged from $9,159 to $10,298. AEs were commonly seen in pts treated with 1st-line T and C (94.6% and 83.7%). On average, the total monthly incremental cost associated with AEs was 38% higher ($3,547) for T and 9% higher ($854) for C. IP and other drug costs accounted for a majority of these costs. Of 1,084 2nd-line pts, 66% received T and 34% C, with average monthly total costs ranging from $5,950 to $12,979. 94.4% of T pts and 84% of C pts in the 2nd-line had an AE. The average total monthly incremental cost associated with AEs for T was $5,320 and $4,933 for C (69.5% and 82.9% higher vs pts w/o AEs). Pharmacy costs accounted for a majority of increased costs seen in pts with AEs treated with T; IP and OP accounted for a majority of these costs in pts treated with C. Conclusions: This is the 1st study assessing costs associated with AEs for tx of mBC. AEs are associated with a substantial economic burden that is mainly explained by increased IP, OP, and pharmacy costs.