Impact of initiating oral anticancer agents for leukemia on adherence to medications for multiple chronic conditions

Introduction Increased use of oral anticancer agents (OAAs) has empowered adults with chronic lymphocytic leukemia (CLL) and chronic myelogenous leukemia (CML) to manage their therapy, but this shift may complicate medication use, particularly among adults with multiple chronic conditions (MCC). Methods This retrospective cohort study used 2013-2018 commercial and Medicare claims data to assess medication use in adults with CML or CLL. To be included, patients must have been at least 18 years old, diagnosed with and had 2+ claims for an OAA indicated for either CML or CLL, continuously enrolled 12 months before and after OAA initiation, and treated for (2+ fills) at least two select chronic conditions. Proportion of days covered (PDC) determined medication adherence and was compared for 12 months before and after OAA initiation by Wilcoxon signed-rank tests, McNemar's tests, and difference-in-differences models. Results Among CLL patients, mean OAA adherence in the first year of therapy was 79.8% (SD: 21.1) and 74.7% (SD: 24.9) for commercial and Medicare patients, respectively; mean adherence for CML patients was 84.5% (SD: 15.8) and 80.1% (SD: 20.1) for commercial and Medicare patients, respectively. Adherence and the proportion adherent (PDC >= 80%) to comorbid therapies was generally unchanged following OAA initiation. Consistently unremarkable changes in MCC adherence were observed in 12-month difference-in-differences models, but significant decline was observed in MCC adherence after 6 months of OAA use. Conclusions OAA initiation among adults with CML or CLL was not associated with significant, initial changes to adherence to medications for chronic diseases.