An analysis of tyrosine kinase inhibitor initiation and adherence in Medicare beneficiaries with chronic myeloid leukemia suggests that out-of-pocket costs may be a barrier to treatment.
An analysis of tyrosine kinase inhibitor (TKI) initiation and adherence in Medicare beneficiaries with chronic myeloid leukemia (CML) suggests that out-of-pocket costs may be a barrier to treatment. Only two-thirds of patients started TKI therapy within 180 days of diagnosis.
“There has been a dramatic increase in the number of orally administered oncology treatments in recent years,” wrote study authors led by Stacie B. Dusetzina, PhD, of the University of North Carolina at Chapel Hill. That move away from office-based infusions raises questions about medication adherence, and previous research has focused on relatively cheap medications such as endocrine therapy or on those with private insurance.
The new analysis focused on Medicare beneficiaries, and on CML due to the strong indication for TKI use in that malignancy. The researchers used SEER-Medicare data on 393 individuals diagnosed with CML between 2007 and 2011; the results were published online ahead of print in the Journal of Clinical Oncology.
The mean age at diagnosis was 77 years, with more than 40% of patients older than 80. About 40% were classified as receiving cost-sharing subsidies. In total, 68.2% of patients initiated TKI therapy within 180 days after diagnosis. When the analysis was restricted to only those who were alive during that full 180-day period, the year of diagnosis and living in a large metropolitan area were significantly associated with increased TKI use. Age older than 80 compared to younger than 70 was associated with reduced usage.
The median time to TKI initiation among initiators was 75 days, and receipt of cost-sharing subsidies was associated with earlier initiation (hazard ratio [HR], 1.35 [95% CI, 1.05–1.84]). Cost-sharing subsidies were not significantly associated with initiation within 180 days, with an HR of 1.08 (95% CI, 0.92–1.27).
Among those who ever started TKI therapy, 61% were considered adherent within the first 180 days after initiation. Age older than 80 years compared with younger than 70 was significantly associated with a reduced likelihood of adherence (adjusted risk ratio [RR], 0.74 [95% CI, 0.56–0.94]). Year of diagnosis was also significantly associated with adherence, with increasing adherence in later years (adjusted RR, 1.07 [95% CI, 1.01–1.13]).
“Medicare beneficiaries’ use of TKIs was far lower than expected,” the authors wrote. They noted that the price of 1 year of TKI therapy with imatinib, dasatinib, or nilotinib ranged from about $9,000 to $10,000; prior research has shown that roughly half of the elderly population has below $13,800 in liquid assets available, and TKI initiation would require more than $3,000. “It is possible that patients without prescription drug cost-sharing subsidies may delay initiating treatment as they work to obtain funds to cover these high upfront costs.”
Imatinib’s loss of patent protection in 2016 may help lower these costs with the entry of generic options to the market. Even still, the authors note that patients may face out-of-pocket costs of at least $125 per month, which may still offer a barrier to treatment.