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Using Encounter-Level Data for Risk-Adjustment of Antimicrobial Use Comparisons: Feasibility and Variable Selection
Rebekah W Moehring1, Michael E Yarrington1, Elizabeth Dodds Ashley1
1Department of Medicine, Division of Infectious Diseases, Duke Center for Antimicrobial Stewardship and Infection Prevention, Duke University, Durham, North Carolina, USA.
External comparisons of hospital antimicrobial use (AU) can inform stewardship strategies. Encounter-level data and machine learning models proved feasible and meaningful for risk-adjustment, with agnostic approaches performing comparably to expert-adjudicated ones.
Area of Science:
- Healthcare Analytics
- Health Informatics
- Antimicrobial Stewardship
Background:
- External comparisons of hospital antimicrobial use (AU) require risk-adjustment using encounter characteristics to inform antimicrobial stewardship program strategy.
- Barriers to encounter-level modeling include data collection feasibility and optimal variable selection for risk adjustment.
Purpose of the Study:
- To measure achievements in sharing validated, encounter-level AU data among a multisystem hospital collaborative.
- To compare variable selection strategies for AU risk-adjustment models using retrospective analyses.
Main Methods:
- Utilized electronic health record data from 50 US hospitals (2020-2021) for model training and testing.
- Compared four input variable strategies: diagnosis-related groups, Elixhauser comorbidities, agnostic Clinical Classification Software Refined (CCSR), and adjudicated CCSR.
- Employed gradient-boosted machine tree-based models to estimate antibacterial days of therapy (DOT), measuring accuracy with mean absolute error (MAE).
Main Results:
- Fifty of 76 hospitals successfully shared validated datasets.
- Modeling strategies with more CCSR inputs yielded the lowest MAE.
- Agnostic and adjudicated strategies showed highly correlated estimates and similar influential variables.
Conclusions:
- Expert adjudication was resource-intensive and did not yield superior results compared to an agnostic approach.
- Risk-adjustment using extensive encounter-level data and machine learning is feasible and valuable for future hospital AU assessments.
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