Adherence to oral anticancer chemotherapies and estimation of the economic burden associated with unused medicines.

Background The list of oral and expensive chemotherapy agents has lengthened over the last few years and has created unique medication adherence concerns. In a real-life setting, patients often do not take their medications as prescribed. This pattern is associated with poor outcomes and increased health care costs. Objectives To estimate the adherence to oral anticancer chemotherapies and to determine the economic burden of unused medicines due to patients' death. Setting Alsace (France). Method This retrospective study was carried out by using ERASME, an Insurance Healthcare database. Main outcome measures Adherence was calculated using medication possession ratio and economic impact using prescription refill data. Results 10,734 patients were treated with oral anticancer medicines (cytotoxic agents, hormonal and targeted therapies). Averaged adherence of 0.86 was observed although it varied significantly between subclasses (cytotoxic agents: 0.69 ± 0.14, hormonal therapy: 0.91 ± 0.17 and targeted therapy: 0.79 ± 0.17). 1631 patients died during the study period. The expenses related to unused chemotherapies amounted to €152,175. Conclusions Our data showed that overall adherence to oral anticancer medicines was above the acceptable limit of adherence of 80% with a marked graduation in values between cytotoxic agents, hormonal and targeted therapies. These statistical significant differences in medication possession ratio could be related to the intrinsic toxicity of the three subclasses of molecules, their tolerance and adverse effects. To limit the cost associated with unused medicines, interventions such as dispensing expensive oral anticancer chemotherapies per unit over shorter periods and not only on monthly intervals could be implement.