Patients with chronic myeloid leukemia (CML) and high out-of-pocket (OOP) costs for treating their disease have a 70% chance of discontinuing treatment and a 42% chance of nonadherence to treatment compared with patients with lesser copays. These conclusions, which were recently published online (Dusetzina SB, et al. J Clin Oncol. 2014;32:306-311), have dire implications for a growing population of patients with CML.
“Our findings highlight the potentially harmful effects of high copayment requirements on patients with CML,” wrote lead investigator Stacie B. Dusetzina, PhD, Research Assistant Professor of Medicine, University of North Carolina at Chapel Hill, and colleagues.
The treatment in question, imatinib (Gleevec), a tyrosine kinase inhibitor (TKI), is one of the most effective anticancer drugs ever developed. Before its development, the median survival for patients with CML was 5 to 6 years. With the advent of imatinib, treatment-adherent patients with CML can now expect to live a nearly normal life span.
However, nonadherence to imatinib (a once-daily oral medication) can result in treatment failure as a result of the rise of imatinib-resistant CML clones. Although overcoming resistance with recently developed second-generation TKIs is possible, the cost for these newer agents is as high as, if not higher than, that of imatinib.
In their cost-sharing versus adherence analysis, Dr Dusetzina and colleagues looked at health plan claims from 2002 to 2011 for patients with CML initiating treatment with imatinib (N = 1541). Treatment discontinuation was defined as a gap of 60 days or more in prescription refills after the number of pills previously received were exhausted. Adherence was defined as drug coverage for 80% or more of the treatment period. The primary independent variable was the OOP cost for a 30-day supply of imatinib.
“Although we selected our cohort on the basis of imatinib initiation,” Dr Dusetzina and colleagues stated, “our outcome measure included adherence to any TKI used during our study period since patients may have been switched to another TKI (dasatinib or nilotinib) because of intolerance or failure to respond to imatinib.” (Previous studies have shown that nonadherence in CML is common in ≥33% of patients, and 100% adherence is rare.)
The results of the analysis showed that the mean copayment required for a 30-day supply of imatinib was $108—although there was a wide range of payments, with patients in the lowest 25th percentile paying $17 and those in the upper 75th percentile paying $53.
Treatment continuation and discontinuation were often related to the patients’ cost-sharing for the drug: only 10% of patients with relatively lower copay requirements discontinued their TKI compared with 17% of patients with higher copayments who discontinued therapy during the first 180 days of treatment. This translates into a 70% increase in the risk of discontinuing TKIs among patients with higher copays.
For treatment adherence, 21% of patients with CML and lower copays were nonadherent to their TKI therapy compared with 30% of patients with the higher financial burden. These patients with a higher copay were 42% more likely to be nonadherent to their prescribed treatment.
Copayments for imatinib were largely related to OOP payments by the patient rather than coinsurance. “Only 6.4% of our sample paid any coinsurance for imatinib versus 88.5% paying any copayments. Among those with coinsurance requirements, the mean spending on a 30-day supply of imatinib was $286….Costs varied substantially among individuals in our sample, with 6.4% of the sample paying more than $500 for a 30-day supply of imatinib.”
These data, establishing a negative correlation between treatment adherence and OOP expense for CML drugs, are being published at a time when the price for imatinib has steeply risen.
“It is unclear how insurers will respond to recent price increases for imatinib,” wrote Dr Dusetzina and colleagues. “But the recent tripling of price raises questions about the decisions manufacturers make when determining prices.”
