Adherence with oral oncologic treatment in cancer patients: interest of an adherence score of all dosing errors.

ABSTRACT

PURPOSE: Patient nonadherence to oral antineoplastic therapy is a well-recognized barrier to effective treatment. In order to identify patients who may need additional support to become adherent, it is important to have a useful tool that takes into account all the parameters of adherence to prescription. The aim of this prospective study was to evaluate adherence of oral antineoplastic agents and to investigate two calculation methods of adherence score. PATIENTS AND METHODS: Twenty-nine cancer patients were enrolled in this study. Fourteen were treated by capecitabine and 15 patients by aromatase inhibitors. Adherence was measured using a medication event monitoring system and adherence score was calculated by a usual method and a composite adherence score that takes into account missed doses and also intake interval errors (between 2 doses and between meals). RESULTS: Across the 6-month evaluation period, average adherence was 95% with the standard calculation (capecitabine group 89%; aromatase inhibitor group 99%) versus 83% with the composite index (capecitabine group 62%; aromatase inhibitor group 99%) (p = 0.030). The composite calculation permits to highlight more nonadherent patients (29.6 vs. 7.4%), particularly in the capecitabine group (73 vs. 18%, p = 0.001). We report 2 cases identified as nonadherent with composite adherence rate. CONCLUSION: The composite adherence score permits to better evaluate adherence to prescription and to identify barriers to adherence and persistence.