When More Isn’t Better: Examining the Complex Role of ID Consults in Broad-Spectrum Antibiotic Use

At the 2025 SHEA Spring Conference in ChampionsGate, Florida, held from April 27 to 30, 2025, Lucy Witt, MD, assistant professor at Emory University and director of antimicrobial stewardship at Emory Johns Creek Hospital, will present findings from a study examining the relationship between infectious disease (ID) consults and broad-spectrum antibiotic prescribing by hospitalists. The research stems from an ongoing initiative in which Emory hospitalists receive individualized “report cards” reflecting their use of National Healthcare Safety Network (NHSN)-defined broad-spectrum antibiotics, calculated through an observed-to-expected ratio of days of therapy (OER).

To learn more about her presentation, Witt spoke with Infection Control Today^® (ICT^®).

The study aimed to evaluate whether high antibiotic use could be attributed to the presence of ID consults. Researchers stratified hospitalists into 5 groups based on their “consult density”—the proportion of patients receiving an ID consult—and then compared average prescribing patterns across those groups. Results showed that while ID consult frequency did influence prescribing behavior, the effect was not linear. For example, providers with moderate consult density had higher mean days of therapy than those at the lowest or highest extremes.

“We're presenting our project, which looked at the impact of infectious disease consultants on hospital medicine and broad-spectrum antibiotic prescribing,” Witt told ICT. “So, the concept is that when we look at the broad-spectrum use of antibiotics prescribed by hospitalists, those are NHSN-defined broad-spectrum hospital-onset antibiotics. These are broad-spectrum antibiotics that cover things like Pseudomonas, so back then, carbapenem 17, how much of the prescribing that we see the hospitals doing is due to having an ID consultant on the patient's case. And the reason we want to look at this at Emory, is that we are doing an ongoing trial, the methods of which have already been published, giving hospitalists a report card on their prescribing of this, and we create a metric of prescribing which is an observed-to-expected ratio of days of therapy (OER) and the hospitals have enjoyed receiving this information about how well they're doing in their broad-spectrum antibiotic prescribing. However, they gave us feedback on the research team that they were concerned that a lot of their broad-spectrum antibiotic prescribing was actually driven by having an ID consultant see their patient.”

Witt said that the study's most surprising result was that “the relationship between the ID consult density and days of therapy was not linear. We didn't see a nice [line] as the consults increase, so did the days of therapy [which] were surprising to me, and as I mentioned, that could just be due to the fact that we only have a small percentage of provider periods in that high-density group, where half of the patients got an ID consult. But I think that speaks to the nuances of the question, that not every patient is the same, not every hospital is the same, not every ID consultant is the same, and there's inherent variability. And we're trying to distill it down to this one consult variable, even though it's this complicated, multifaceted interaction between providers and patients.”

Incorporating ID consult density into the OER model did not dramatically change providers' performance ratings, indicating that while ID involvement influences prescribing, it does not fully explain high antibiotic use. These findings underscore the complexity of stewardship and the need to interpret performance metrics in context. They also highlight the importance of building credibility and fostering collaboration between stewardship teams and hospitalists. The study reinforces the value of data-driven, provider-informed approaches to optimizing antibiotic use—an essential strategy in the fight against antimicrobial resistance.