Estimated greenhouse gas emissions associated with unnecessary intravenous antimicrobials administered in the hospital setting.

Background: Healthcare has deleterious impacts on the environment through production of massive amounts of waste leading to generation of greenhouse gas (GHG) emissions. Single-use materials used for preparation and administration of intravenous (IV) medications are a large component of hospital waste. Transitioning medications from the IV-to-oral (PO) route, called switch therapy, may be a means of decreasing unnecessary waste and associated emissions arising from hospital care. Methods: This was a retrospective cohort study involving adult patients receiving IV antimicrobials with a highly bioavailable PO equivalent at a large academic medical center. For a randomly selected subset of patients, the mean number of IV days of therapy (DOT) for which PO therapy could have been administered based on our institution's policy was determined for each antimicrobial. This proportion was applied to the full cohort to estimate the total unnecessary IV DOT. A GHG emissions estimation tool was used to estimate the emissions generated from the excess antimicrobials. Results: During the study period, 15,037 IV DOT were administered, of which 9,694 DOT (64%) were estimated to be unnecessary. This was estimated to have generated 2,049 kilograms of total waste and 0.353 metric tons of carbon dioxide equivalents, equivalent to 904 miles driven. Conclusions: Optimizing IV-to-PO antimicrobial switch policies may be an effective way to decrease hospital environmental impact through reduction of single-use supply waste and associated emissions. Future work should prioritize evaluating other potential antimicrobial stewardship interventions as a means to reduce GHG emissions.