Financial Burden of Discarded Weight-based Antineoplastic Drugs to Payers and Patients in the Private Insurance Market.

Background: Our study estimated insurance payments and patient out-of-pocket (OOP) expenses associated with discarded weight-based intravenous antineoplastic drugs for privately insured US adult patients with cancer. Methods: We identified patients who received weight-based antineoplastic drugs from a 2017 MarketScan health risk assessment (IBM Corp, Armonk, NY) linked to claims data. Using weight information in the health risk assessment, we derived the recommended dose and calculated the percentage of drugs discarded. We applied β-regression to determine factors associated with the discarded percentages. To compare patients with and without high-deductible plans, we employed a generalized linear model and a 2-part model to examine insurance payment and OOP expense, respectively. All statistical tests were 2-sided. Results: Of 27 350 claims for 58 weight-based antineoplastic drugs from 1970 patients, the median discarded percentage was 9.8% (mean [SD] = 12.8% [10.5%]). Aside from drug and tumor type, statistically significantly higher discarded percentages were found for patients in the lowest weight group (5.5% [95% confidence interval = 4.7% to 6.4%]; Conclusions: Private insurers incurred substantial financial burden from discarded weight-based antineoplastic drugs. Although the OOP expenses of discarded drugs were modest for most privately insured patients with cancer, approximately 5% spent more than $400 on the discarded drugs. Policies designed to reduce drug waste from single-dose, weight-based antineoplastic drugs should evaluate their financial consequences for payers and patients.