Adherence to tyrosine kinase inhibitors among Medicare Part D beneficiaries with chronic myeloid leukemia

Chan Shen, Bo Zhao, Lei Liu, Ya Chen Tina Shih

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


BACKGROUND: Tyrosine kinase inhibitors (TKIs) improve the survival of patients with chronic myeloid leukemia (CML) dramatically; however, nonadherence to TKI therapy may lead to resistance to the therapy. TKIs are very expensive and are covered under Part D insurance for Medicare patients. To the authors' knowledge, the impact of low-income subsidy status and cost sharing on adherence among this group has not been well studied in the literature. METHODS: Surveillance, Epidemiology, and End Results (SEER) registry data linked with Medicare Part D data from the years 2007 through 2012 were used in the current study. The authors identified 836 patients with CML with Medicare Part D insurance coverage who were new TKI users. Treatment nonadherence was defined as a binary variable indicating the percentage of days covered was <80% during the 180-day period after the initiation of TKI therapy. Logistic regression was used to examine the relationship between out-of-pocket costs per 30-day drug supply, Medicare Part D plan characteristics, and treatment adherence while controlling for other patient characteristics. RESULTS: Overall, 244 of the 836 patients with CML (29%) were nonadherent to targeted oral therapy during the 180 days after the initiation of treatment with TKIs. The multivariable logistic regression demonstrated that patients with heavily subsidized (odds ratio, 6.7; 95% confidence interval, 2.8-15.9) and moderately subsidized (odds ratio, 3.0; 95% confidence interval, 1.4-6.5) Medicare Part D plans were much more likely to demonstrate nonadherence compared with patients without a subsidy. CONCLUSIONS: 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. Cancer 2018;124:364-73.

Original languageEnglish
Pages (from-to)364-373
Number of pages10
Issue number2
StatePublished - Jan 15 2018


  • Medicare Part D
  • Surveillance, Epidemiology, and End Results (SEER)
  • adherence
  • chronic myeloid leukemia (CML)
  • tyrosine kinase inhibitors (TKIs)


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