Comparing The Environmental Impact of Inpatient IV Antimicrobial Administration With OPAT

Andrew J Hale, MD

Image credits: The University of Vermont Health Network

Finlay Pilcher, MD

Image credits: LinkedIn

The climate crisis and antimicrobial resistance (AMR) are 2 of the world’s top health emergencies. Climate change and AMR are inextricably linked: rising temperatures and extreme weather events facilitate the spread and adaptation of pathogens. In turn, resistant organisms require more health care intervention and, correspondingly, leave a larger climate footprint.¹ In an effort to intervene in this cycle, there has been enhanced interest in identifying ways to reduce the environmental impact of delivering health care.

Minimizing hospitalization is a significant area of focus. Hospitals have a substantial climate footprint through large consumption of energy and electricity along with the generation of considerable waste. Hospitalization also exacerbates AMR through increased use of intravenous (IV) antimicrobials and exposure to hospital-acquired infections.²Click or tap here to enter text. However, the specific role of environmental impact on how and where antibiotics are delivered has been underassessed to date.

A recent study by Cole and colleagues (3) investigated IV antimicrobial administration as an opportunity to mitigate the health care climate footprint and threat of rising AMR. The authors created a model to compare the environmental impact of inpatient IV antimicrobial administration to 4 common outpatient parenteral antibiotic therapy (OPAT) care pathway scenarios. The study outcomes were carbon dioxide (CO₂) emissions, water used, and waste generated in the 4 scenarios.

The model was created based on adults (age >18 years old) in England with infections suitable for treatment with IV ceftriaxone for an average duration of 15.3 days. The 4 scenarios analyzed were as follows:

• Scenario 1: Self-administration OPAT
• Scenario 2: Nurse-assisted home OPAT administration
• Scenario 3: Nurse-assisted hospital OPAT administration
• Scenario 4: Inpatient administration

The authors used expert opinion and relevant source documents to collect data and calculate the environmental impact of each care pathway. Some of the assumptions of the model were that nurses traveled an average of 11 miles per journey; that patients receiving OPAT used an elastomeric pump, whereas those in the inpatient pathway were treated via IV bolus; and that patients were monitored by weekly blood tests.

The authors found that inpatient administration was associated with considerably higher emissions compared to OPAT (Table³). Self-administration of OPAT was associated with the largest reductions compared to inpatient hospitalization, including a CO₂ reduction of 85%, a water use reduction of 78%, and a waste reduction of 91%. The nurse-assisted pathways were also associated with a reduction in CO₂ emissions, water use, and waste generation compared to the inpatient pathway.

Table. Environmental Impact per Patient Population³

Table 1 adapted from Cole et al, Table 3.

The most substantial contributor to CO₂ emissions, water used, and waste generated was the requirement of a bed associated with inpatient hospitalization. Within the OPAT care pathway scenarios, the largest contributors to environmental impact were manufacturing of the pump, reconstitution of ceftriaxone, treatment failure requiring rehospitalization (estimated at 6.4%), and travel in the nurse-assisted pathways. 

While this study provides a compelling argument in favor of OPAT compared to inpatient antimicrobial administration with regard to waste and emissions, the generalizability of the model to clinical practice may be limited. Many of the study assumptions are based on data from England, and it is not clear that care pathways or associated impact would be equivalent in other settings, particularly those with limited resources. Furthermore, the assumption of 11-mile travel may underestimate the environmental impact of OPAT in health care regions in more rural areas.

While the use of ceftriaxone is convenient for modeling, given its once-daily administration, other antimicrobials commonly used for OPAT may result in additional environmental impact not captured by this study. Other agents that require more volume, dosing, or monitoring may have corresponding increases in water used for reconstitution and CO₂ emitted from travel, already 2 of the most significant contributors to environmental impact identified by this study in the OPAT care pathway scenarios.

Nevertheless, Cole et al add support to the growing case that, when feasible and safe, patients should be treated in the community rather than the hospital.³ This approach has multifaceted benefits, including reducing nosocomial infections, antimicrobial exposure, health care costs, and overall environmental impact. Additional investigation is needed to evaluate the applicability of this model, as well as its generalizability and ultimately, broad feasibility.

References

1.van Bavel B, Berrang-Ford L, Moon K, et al. Intersections between climate change and antimicrobial resistance: a systematic scoping review. Lancet Planet Health. 2024;8(12):e1118-e1128. doi:10.1016/S2542-5196(24)00273-0

2.Prasad PA, Joshi D, Lighter J, et al. Environmental footprint of regular and intensive inpatient care in a large US hospital. Int J Life Cycle Assess. 2022;27:38-49. doi:10.1007/s11367-021-01998-8

3.Cole A, Aspin J, Laird S, Acri F, Galley S, Collins M. The environmental impact of intravenous antimicrobial therapies: a comparison of OPAT and inpatient administration care pathways. JAC Antimicrob Resist. 2025;7(2):dlaf030. doi:10.1093/jacamr/dlaf030