Higher Copays for CML Drugs Associated With Higher Non-Adherence Rates

Chronic myeloid leukemia (CML) patients with higher copayments for the tyrosine kinase inhibitor imatinib were more likely to discontinue the drug or be non-adherent, according to a new study. The cost of imatinib nearly doubled over the 10-year period from 2002 to 2011.

“These increases in drug pricing are not sustainable for our health care system,” said study lead author Stacie B. Dusetzina, of the University of North Carolina at Chapel Hill, in an e-mail. The study, which examined MarketScan health plan claims to identify 1,541 adults aged 18 to 64 who initiated imatinib therapy for CML during the study period, was published online in the Journal of Clinical Oncology on December 23.

The monthly mean copayment for imatinib was $108 over the course of the study, and the median was $30, with patient costs ranging from $0 to $4,792. The monthly copayment increased from an average of $55 in 2002 to $145 in 2010. The total monthly expenditure for the drug, which included patient copayment as well as health plan expenditure, rose from $2,798 to $4,892.

The investigators divided the patients into quartiles based on monthly copayments for imatinib. Those in the highest payment quartile discontinued the drug within 180 days of initiation at a 17% rate, compared with 10% for those in the lowest quartile; the adjusted relative risk of discontinuation was 1.70 (95% CI, 1.30-2.22). Similarly, rates of non-adherence-defined as having less than 80% of days with the TKI available during those 180 days after initiation-were 30% in the highest quartile compared with 21% in the lower copayment group, for an adjusted risk ratio of 1.42 (95% CI, 1.19-1.69).

“Part of making treatments more affordable to patients is improving insurance benefit designs to reduce patient cost sharing,” Dusetzina said. She also noted in a press release that the study likely underestimates the negative effects of high costs, in that it did not include those patients who could not afford to even initiate therapy.

The costs of CML drugs have come under increasing scrutiny in recent years, thanks in part to their long-term efficacy. Many patients can achieve and maintain excellent results with TKIs, but the need to continue on the drugs indefinitely-often for many years and even decades-highlights the importance of containing their costs. Dusetzina said that pricing of these and other expensive drugs sometimes seems arbitrary in the United States. “We, as health care consumers, should demand more transparency regarding drug pricing, particularly when prices change so drastically without obvious reasons,” she said.