Benchmarking antimicrobial use to antimicrobial resistance: a comparative study of two hospitals using current National Healthcare Safety Network (NHSN) metrics.

Objective: We aimed to determine whether benchmarking antimicrobial use (AU) to antimicrobial resistance (AR) using select AU/AR ratios is more informative than AU metrics in isolation.

Design: We retrospectively measured AU (antimicrobial therapy days per 1,000 days present) and AU/AR ratios (specific antimicrobial therapy days per corresponding AR event) in two hospitals during 2020 through 2022. We then had antimicrobial stewardship committee members evaluate each AU and corresponding AU/AR value and indicate whether they believed it represented potential overuse, appropriate use, or potential underuse of the antimicrobials, or whether they could not provide an assessment.

Setting: Two acute-care hospitals.

Patients: Hospitalized patients.

Results: In semi-annual facility-wide analyses, echinocandins had a median AU/AR ratio of 658.5 therapy days per fluconazole-resistant Candida event in Hospital A, IV vancomycin had a median AU/AR ratio of 114.9 and 108.2 therapy days per methicillin-resistant Staphylococcus aureus event in Hospital A and B, respectively, and linezolid had a median AU/AR ratio of 33.8 and 88.0 therapy days per vancomycin-resistant Enterococcus event in Hospital A and B, respectively. When AU and AU/AR values were evaluated by stewardship committees, more respondents were able to assess antimicrobial use based on AU/AR values compared to AU values. Based on AU/AR ratios, most respondents identified potential overuse of echinocandins and IV vancomycin in Hospital A, and potential overuse of linezolid and IV vancomycin in Hospital B.

Conclusion: Select AU/AR ratios provided informative metrics to antimicrobial stewardship personnel, which can be used to motivate audits of antimicrobial administration to determine appropriateness.