Many patients skip doses or stop taking medication entirely when their share of the costs becomes too high. Using data from health plan claims for the anticancer drug imatinib (Gleevec) filed between 2002 and 2011, Stacie B. Dusetzina, PhD, of the University of North Carolina School of Medicine in Chapel Hill, found that patients with higher copayments were 70% more likely to stop taking their cancer treatment and 42% more likely to skip doses. The study, published by the Journal of Clinical Oncology (2013; doi:10.1200/JCO.2013.52.9123), is one of the first to examine the effect of high out-of-pocket drug costs for targeted cancer therapies.

The research team used health plan claims from privately insured adult patients age 18 to 64 years to examine the relationship between out-of-pocket costs and treatment adherence. The data showed that insurance copayments for imatinib ranged from $0 to $4,792 for a 30-day supply, with the costs increasing over the study years.

The data used in the study only included patients on employer-based plans. Most persons had low out-of-pocket costs—the most common cost was $30 for a 30-day supply—but copayments and co-insurance amounts required of patients varied substantially. The data has implications beyond imatinib. The cost of many new pharmaceuticals for rare conditions can cost insurers and patients more than $100,000 year.

“Our results are particularly relevant for specialty pharmaceutical products, those that cost [more than] $10,000 a month, however, the lessons learned likely relate to any pharmaceutical product that has high out-of-pocket costs,” said Dusetzina.