Volume-adjusted antimicrobial prescribing rate: An automated method for identifying antimicrobial over-prescribers in ambulatory care

BACKGROUND: A major target for outpatient antimicrobial stewardship has been the unnecessary use of antimicrobials, particularly for acute respiratory tract infections (ARTIs). The objective of this study was to determine whether data electronically extracted from the medical record (i.e., volume-adjusted antimicrobial prescribing rate) could identify outpatient providers who are more likely to prescribe unnecessary antimicrobials. METHODS: At a single VA medical center, patient visits during 2016 to primary care or the emergency department (ED) were retrospectively reviewed if associated with an ICD-10 code for cystitis or an ARTI. Using manual chart-review, an over-treatment rate was calculated for each provider by determining the frequency at which antimicrobials were prescribed when not indicated. A volume-adjusted antimicrobial prescribing rate was determined by extracting data on all antimicrobials prescribed by each provider and adjusting for the total number of patient-visits for that provider. RESULTS: Manual audits to determine antimicrobial necessity were performed on 633 ED visits and 247 primary-care visits. Antimicrobials were not indicated in 51% (324) of ED visits and 58% (144) of primary care visits. For 14 ED providers, the median antimicrobial-prescribing volume was 13.7 prescriptions per 100 patient-visits (IQR 12.5-14.8), and the median over-treatment rate was 47% (IQR 28-64%). Among 7 primary care providers, the median volume-adjusted antimicrobial prescribing rate was 8.1 prescriptions per 100 patient-visits (IQR 7.3-8.6), and the median over-treatment rate was 33% (IQR 31–59%). There was a positive correlation between a provider’s volume-adjusted antimicrobial prescribing rate and their overall rate of over-treatment in both the ED (r = 0.67, P < 0.01) and primary care (r = 0.80, P = 0.03). CONCLUSION: In this small study, electronically-extracted data on a provider’s rate of volume-adjusted antimicrobial prescribing strongly correlated with the frequency at which unnecessary antimicrobials were prescribed, particularly in primary care. Comparing providers within a given outpatient setting on their volume-adjusted antimicrobial prescribing rate may be an efficient way to identify over-prescribers. DISCLOSURES: All authors: No reported disclosures.