Adherence to tyrosine kinase inhibitor therapy for chronic myeloid leukemia: a Brazilian single-center cohort.

The introduction of oral tyrosine kinase inhibitors (TKIs) has dramatically improved outcomes in chronic myeloid leukemia (CML) patients. However, treatment success is directly related to good long-term adherence. Adherence to TKI therapy was evaluated in 137 CML patients over a period of 1 year. Three different methods were used to evaluate adherence: the Morisky questionnaire, a medication diary and the medication possession ratio (MPR). MPR was the most effective method of assessing adherence (median adherence 96.5%; p = 0.0001), duration of TKI treatment was the variable that most impacted adherence (p = 0.03), and the MPR was inversely correlated to the duration of therapy. Additionally, participation in clinical trials, better quality of life as reported by patients and higher socioeconomic status were all related to better compliance (p = 0.02, 0.007 and 0.01, respectively). For patients treated with imatinib for 24-48 months (n = 22), individuals with major molecular response (MMR) had a significantly better MPR than those who failed to achieve MMR (p = 0.04). In this group, the mean MPR was 87% for the population without apparent molecular response and 96% for those achieving MMR; however, only 24% of the patients were completely adherent to TKI treatment.