Impact of Allocation on Survival During Intermittent Chemotherapy Shortages: A Modeling Analysis.

Abstract

Intermittent shortages of chemotherapeutics used to treat curable malignancies are a worldwide problem that increases patient mortality. Although multiple strategies have been proposed for managing these shortages (eg, prioritizing patients by age, scarce treatment efficacy per volume, alternative treatment efficacy difference), critical clinical dilemmas arise when selecting a management strategy and understanding its impact. We developed a model to compare the impact of different allocation strategies on overall survival during intermittent chemotherapy shortages and tested it using vincristine, which was recently scarce for 9 months in the United States. Demographic and treatment data were abstracted from 1,689 previously treated patients in our tertiary-care system; alternatives were abstracted from NCCN Clinical Practice Guidelines in Oncology for each disease and survival probabilities from the studies cited therein. Modeled survival was validated using SEER data. Nine-month shortages were modeled for all possible supply levels. Pairwise differences in 3-year survival and risk reductions were calculated for each strategy compared with standard practice (first-come, first-served) for each 50-mg supply increment, as were supply thresholds above which each strategy maintained survival similar to scenarios without shortages. A strategy prioritizing by higher vincristine efficacy per volume and greater alternative treatment efficacy difference performed best, improving survival significantly (P<.01) across 86.5% of possible shortages (relative risk reduction, 8.3%; 99% CI, 8.0-8.5) compared with standard practice. This strategy also maintained survival rates similar to a model without shortages until supply fell below 72.2% of the amount required to treat all patients, compared with 94.3% for standard practice. During modeled vincristine shortages, prioritizing patients by higher efficacy per volume and alternative treatment efficacy difference significantly improved survival over standard practice. This approach can help optimize allocation as intermittent chemotherapy shortages continue to arise.