Individuals with chronic myeloid leukemia (CML) with heavily subsidized Medicare part D plans who initiate tyrosine-kinase inhibitor (TKI) therapy are significantly less likely to adhere to therapy compared with patients without a subsidy, according to a recent study.
Although TKI use is associated with significantly improved survival among patients with CML, nonadherence may cause resistance to the therapy. Furthermore, TKIs, which are covered under part D insurance for Medicare recipients are costly. Currently, little is known about the effects of low-income subsidy status and cost sharing on the rates of TKI therapy adherence in patients with CML.
Chan Shen, PhD, MD Anderson Cancer Center, University of Texas, and colleagues assessed data from 2007-2012 on 836 patients with CML who were new TKI users. Patient data were obtained from the Surveillance, Epidemiology, and End Results (SEER) registry data, which had been linked with Medicare Part D data.
The researchers identified treatment nonadherence as a binary variable indicating that the percentage of days covered had been below 80% in the 180 days following TKI therapy initiation. The association between out-of-pocket costs per 30-day drug supply, Medicare Part D plan characteristics, and treatment adherence was investigated via logistic regression. Results were controlled for other patient characteristics.
The study’s findings were published in Cancer (online October 4, 2017; doi:10.1002/cncr.31050).
Results indicated that 244 patients (29%) had been nonadherent to targeted oral therapy in the 180 days following TKI initiation. According to multivariable logistic regression, patients with heavily subsidized Medicare part D plans were significantly more likely to be nonadherent to TKI therapy vs those without a subsidy.
“The current population-based study found a significantly higher rate of nonadherence among heavily subsidized patients with substantially lower out-of-pocket costs, which suggests that future research is needed to help lower the nonadherence rate among these individuals,” the researchers concluded.—Christina Vogt