Medication adherence among adults prescribed imatinib, dasatinib, or nilotinib for the treatment of chronic myeloid leukemia.

BACKGROUND: Oral tyrosine kinase inhibitors are the standard of care for chronic myeloid leukemia. Tyrosine kinase inhibitors are administered in an outpatient setting for an indefinite period which may negatively impact adherence. Non-adherence to tyrosine kinase inhibitors is associated with disease progression.

OBJECTIVES: To evaluate the need for adherence-enhancing interventions, this study was designed to determine the proportion of chronic myeloid leukemia patients non-adherent to their tyrosine kinase inhibitor regimen. The secondary objective was to identify the influence of patient characteristics on tyrosine kinase inhibitor adherence.

METHODS: Cross-sectional retrospective chart and dispensing record reviews were performed to identify patients receiving a tyrosine kinase inhibitor from 1 June 2010 to 31 January 2012. Adherence was evaluated using the medication possession ratio.

RESULTS: A total of 124 patients were included. Thirty-eight (31%) patients were non-adherent to their tyrosine kinase inhibitor regimen. Patients not receiving concurrent medications were more likely to be non-adherent (odds ratio (OR) 2.33, 95% confidence interval (CI) 1.05-5.13, p=0.04). The median medication possession ratio was 0.95 (IQR=0.83-1.07). Median medication possession ratio was lower in patients receiving imatinib compared to dasatinib or nilotinib (0.95 vs. 1.00, p=0.01) and in those less than 50 years old compared to those greater than 50 years old (0.92 vs. 0.97, p=0.02).

CONCLUSIONS: Optimal tyrosine kinase inhibitor adherence in chronic myeloid leukemia patients poses a significant obstacle in achieving best possible outcomes while reducing healthcare costs. In this study, one in three chronic myeloid leukemia patients treated with a tyrosine kinase inhibitor were non-adherent to their regimen. Those at higher risk of non-adherence were on no concurrent medications, less than 50 years old, and those treated with imatinib. Active intervention to improve tyrosine kinase inhibitor adherence should be developed, implemented, and evaluated to improve patient outcomes at our center.