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

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.