Adjusting for Drug Wastage in Economic Evaluations of New Therapies for Hematologic Malignancies: A Systematic Review

Abstract

Purpose: As costs of cancer care rise, there has been a shift to focus on value. Drug wastage affects costs to patients and health care systems without adding value. Historically, cost-effectiveness analyses have used models that assume no drug wastage; however, this may not reflect real-world practices. We sought to identify the frequency of drug wastage modeling in economic evaluations of modern parenteral therapies for hematologic malignancies. Methods: We conducted a systematic literature review of economic evaluations of new US Food and Drug Administration–approved parenteral chemotherapies with indications for the treatment of hematologic malignancies. The primary outcome of interest was the proportion of studies that modeled drug wastage in base-case analyses. If wastage was considered in primary analyses, we reported the impact of wastage on incremental cost-effectiveness ratios (ICERs) and drug acquisition costs. Results: Wastage was considered in base-case analyses in less than one third of all publications reviewed (12 of 38; 32%). Of these, two studies went on to complete sensitivity analyses and reported significant changes in the calculated ICER as a result. In one study, the ICER increased by 32%, and in the second, accounting for wastage changed a positive ICER to a dominant result. Conclusion: Potential costs associated with drug wastage are considered in only one third of modern cost-effectiveness models. The impact of wastage on calculated ICERs and drug acquisition costs is potentially substantial. The modeling of wastage in base-case and sensitivity analyses is recommended for future economic evaluations of new intravenous therapies for hematologic malignancies.