Are the True Impacts of Adverse Events Considered in Economic Models of Antineoplastic Drugs? A Systematic Review

Background Antineoplastic drugs for cancer are often associated with adverse events, which influence patients' physical health, quality of life and survival. However, the modelling of adverse events in cost-effectiveness analyses of antineoplastic drugs has not been examined. Aims This article reviews published economic evaluations that include a calculated cost for adverse events of antineoplastic drugs. The aim is to identify how existing models manage four issues specific to antineoplastic drug adverse events: the selection of adverse events for inclusion in models, the influence of dose modifications on drug quantity and survival outcomes, the influence of adverse events on quality of life and the consideration of multiple simultaneous or recurring adverse events. Methods A systematic literature search was conducted using MESH headings and key words in multiple electronic databases, covering the years 1999-2009. Inclusion criteria for eligibility were papers covering a population of adults with solid tumour cancers, the inclusion of at least one adverse event and the resource use and/or costs of adverse event treatment. Results From 4,985 citations, 26 eligible articles were identified. Studies were generally of moderate quality and addressed a range of cancers and treatment types. While the four issues specific to antineoplastic drug adverse events were addressed by some studies, no study addressed all of the issues in the same model. Conclusion This review indicates that current modelling assumptions may restrict our understanding of the true impact of adverse events on cost effectiveness of antineoplastic drugs. This understanding could be improved through consideration of the selection of adverse events, dose modifications, multiple events and quality of life in cost-effectiveness studies.