Adverse events (AEs) related to chemotherapy for metastatic breast cancer (MBC) create a substantial economic burden that is primarily explained by increased inpatient, outpatient, and pharmacy costs, said Sara A. Hurvitz, MD, of the University of California Los Angeles, who presented an economic analysis at the 2012 Annual Meeting of the American Society of Clinical Oncology.
“In addition, an analysis of healthcare costs stratified by the number of AEs reported by patients showed a clear trend: the economic burden of AEs increases with the number of AEs reported,” she added.
The study is the first to assess costs associated with AEs that occur during treatment for MBC, she said.
Hurvitz led a study sponsored by Genentech that aimed to quantify the economic impact of AEs reported in patients with MBC receiving first- or second-line therapy with taxanes or capecitabine for at least 30 days per treatment episode. Patients were selected from the PharMetrics Integrated Database. The data elements included pharmacy and medical claims from more than 100 healthcare plans in the United States, covering more than 70 million lives between 2000 and 2010.
The eligible cohort included 3222 patients who used a taxane (docetaxel, paclitaxel) first-line (n = 1866), capecitabine first-line (n = 812), taxane second-line (n = 715), or capecitabine second-line (n = 369). Patients treated with both classes during the same episode were excluded. The AE list included almost 2 dozen possible AEs.
AEs were commonly seen in each of the 4 study cohorts. With taxanes, 94.6% of first-line patients and 94.4% of second-line patients experienced at least 1 event during treatment. With capecitabine, 83.7% and 84.0%, respectively, experienced at least 1 AE. Nausea/vomiting was the most common complication with either agent, Hurvitz reported.
In general, patients who experienced no AEs in the study were relatively younger and had fewer comorbidities at baseline.
Incremental Monthly Costs Associated With AEs
The incremental costs associated with chemotherapy-related complications were estimated by comparing the average costs between the cohorts with AEs and without AEs for the 4 treatment groups. The analysis revealed the following:
- Taxanes first-line: AEs were associated with a 38.7% increase in monthly costs, over patients without AEs ($3547). These incremental costs were mainly driven by increased inpatient costs and other drug costs (other than chemotherapy).
- Taxanes second-line: AEs were associated with a 69.5% increase in monthly costs ($5320). Incremental costs were mainly driven by incremental pharmacy costs for chemotherapy and other drugs.
- Capecitabine first-line: AEs were associated with a 9% increase in monthly costs ($4933). Incremental costs were mainly driven by inpatient and outpatient costs.
- Capecitabine second-line: AEs were associated with an 82.9% increase in monthly costs ($4933). Incremental costs were mainly driven by inpatient and outpatient costs.
Increasing AEs per Episode Led to Higher Costs
The more AEs per episode, the greater the cost of care, the analysis further found. For example, for taxane first-line therapy, the mean cost for a treatment without an AE episode was approximately $10,000, which rose to approximately $11,000 in the setting of 1 or 2 AEs and to almost $15,000 in the setting of more than 4 AEs.
For second-line capecitabine, treatment without an AE episode cost approximately $6000, but rose to approximately $14,000 in the setting of more than 4 AEs.
The average monthly costs per type of AE were highest for skin toxicity with taxanes and for constitutional symptoms with capecitabine, both approaching $16,000 on average.
Hurvitz cautioned that the study has limitations: cause-and-effect associations cannot be confirmed and the reported rates are restricted to duration of an episode of treatment and did not take into account complications occurring after treatment ended. It is also a retrospective observational study based on claims data, though this also has the advantage of being a valid, large sample-source of clinical practice data, she pointed out.
“Further research evaluating the clinical and economic consequences of chemotherapy-related AEs in a prospective manner can further characterize the effects seen here,” she said.