Prescription refill, patient self-report and physician report in assessing adherence to oral endocrine therapy in early breast cancer patients: a restrospective cohort study in Catalonia, Spain

AIMS: To compare different methods in order to assess adherence and persistence with oral endocrine therapy in women diagnosed with breast cancer (BC) in Catalonia. MATERIALS AND METHODS: This study covered all women newly diagnosed with stage I, II or IIIa BC and positive hormone receptors at six hospitals in Catalonia (Spain) in 2004. Adherence was assessed on the basis of physician report and patient self-report using a telephone questionnaire. Persistence was measured by refill prescriptions. We used the Kappa index to compare adherence measures and logistic regression to evaluate adherence-related risk factors. RESULTS: The study covered a total of 692 women. Adherence ranged from 92% (self-report) to 94.7% (physician report), depending on the measure used; persistence was 74.7% at 5 years of follow-up. Low concordance between measures was observed (Kappa range: 0.018-0.267). Patients aged 50-74 years showed higher adherence than those aged