Objectives: Little is known about toxicity-related costs of monoclonal antibody treatments in metastatic colorectal cancer. This study aimed to identify toxicities associated with bevacizumab, cetuximab, and panitumumab and estimate the direct costs of these toxicities.
Methods: Grade 3 and 4 toxicities were identified by a comprehensive literature search. Inpatient costs were estimated using ICD-9 codes and 2007 Medicare payments from the Healthcare Cost and Utilization Project database; costs were converted to 2010 dollars. Outpatient costs were estimated by applying 2010 Medicare reimbursement rates to resource use assumptions (based on in-depth clinical interviews).
Results: Toxicities associated with bevacizumab included hypertension, arterial thrombosis, hemorrhage, gastrointestinal (GI) perforation, fistula, and wound-healing complications; toxicities associated with cetuximab and panitumumab included skin rash, hypomagnesemia, and infusion reactions. The inpatient cost per event was highest for GI perforation (USD 32,443), followed by fistula (USD 29,062), arterial thrombosis (USD 20,346), and wound-healing complications (USD 13,240), while inpatient costs per event for hypomagnesemia and skin rash were among the lowest. The cost per event of toxicities treated in the outpatient setting included USD 185 for skin rash up to USD 585 for wound-healing complications.
Limitations: Treatment costs of toxicities for the outpatient setting were determined using assumptions validated by clinicians, and unit costs were based on Medicare reimbursement rates, which are often lower than the reimbursement rates for commercial health insurance plans. Toxicities included were only grades 3 and 4 adverse events and might be limited by differences between clinical studies.
Conclusions: Monoclonal antibodies have different toxicity profiles and the costs associated with managing these toxicities vary greatly.