Scoring Spectrum: More Metrics for Antibiotic Utilization

Reviewed by Erica Stohs, MD, MPH, University of Nebraska Medical Center

When it comes to measuring antimicrobial utilization (AU), is it ideal that one day of ceftriaxone plus metronidazole is twice as much as one day of meropenem? The standard AU measure days of therapy (DOT) per 1000 days present does not consider spectrum of activity, and this review by Ilges and colleagues examines antibiotic spectrum scoring systems and their applications.

Four antibiotic spectrum scoring systems are reviewed: Madaras-Kelly spectrum score (MKSS), antibiotic spectrum index (ASI), modified ASI, and antibiotic spectrum coverage (ASC). Each assigns a numeric value to quantify spectrum of activity but with different methodologies (Table 1 which also provides comparisons between the systems). MKSS and modified ASI were validated by measuring de-escalation in the setting of pneumonia. IV-to-PO conversion is considered only by MKSS. The main application for these scoring tools is targeting prospective audit & feedback.

The limitations for these tools include lack of consideration of toxicities, impact on gut microbiome, and the lack of adoption and validation in various settings. How to practically implement such a scoring system is another open question.

Ilges D, Tande AJ, Stevens RW. “A broad spectrum of possibilities: spectrum scores as a unifying metric of antibiotic utilization.” CID 2023:77(15 July): 167-73.

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