Chemotherapy dose intensity reductions due to adverse drug reactions in an oncology outpatient setting

OBJECTIVE: the aim of this study was to establish the incidence of adverse drug reactions (ADRs) that prevent administration of planned dose intensity antineoplastic chemotherapy in clinical practice. METHODS: a retrospective cohort study was made of adult oncology patients who received intravenous chemotherapy in an outpatient ward during 2005. Dose delays, dose reductions, dose omissions, or treatment discontinuations with respect to the planned chemotherapy regimen were obtained, and causes were evaluated to identify ADRs. RESULTS: a total of 532 patients were included, involving the administration of 631 chemotherapy regimens. The total number of cycles evaluated was 3553. The incidence of nonadherence to planned treatment due to ADRs was 12.9% cycles (95% CI: 11.8-14.0). Differences according to patient's age were found, patients younger than 65 years showed higher rates of nonadherence due to ADRs. Myelosuppression was the main cause of dose delays, and gastrointestinal and neurological toxicity were reported as the main causes of dose reductions. CONCLUSIONS: the incidence of ADRs preventing planned dose intensity administration has been estimated. Follow-up of nonadherence to antineoplastic chemotherapy prescriptions can be used to evaluate tolerance in the clinical setting. Continuous evaluation of security in clinical practice provides information on benefits outweighing the deleterious effects in specific patient populations where the available data are limited.