Antimicrobial Use Trends Following Implementation of a Pediatric Immunocompromised Infectious Disease Service

Corresponding Author Alex Plattner, MD, MBA; One Children’s Place, St. Louis, MO 63110; aplattner@wustl.edu Funding ASP was supported by an NIH grant (T32 AI106688). Conflict(s) of Interest Madeline M. Cullity, no conflict; Alexander S. Plattner, no conflict; Andrew B. Janowski, no conflict. Background Hospitalized children with medical complexity (CMC) have a greater need for specialized medical teams to receive optimal care. One subspecialty that has evolved in recent years is Immunocompromised Infectious Diseases (ICID). Immunocompromised (IC) patients often have very complex medical histories and clinical courses requiring frequent and prolonged hospitalizations, broad spectrum antimicrobial administration, and an increased risk of rare, unusual, and opportunistic infections. Therefore, it is critical to have a subset of providers who are experts in evaluating these patients to provide specialized care and continuity in their management. While there is an increased demand for sub specialization in ICID, there is a paucity of data regarding the clinical impact of this subspecialty. Thus, we aimed to better characterize the impact of a newly formed ICID group through the following objectives: 1) Quantify the growth of the ICID service through consult volume and type, 2) Determine impact on antibiotic usage by units that frequently utilize the ICID service. Methods A retrospective review was performed using data from the electronic health record (EHR) at St. Louis Children’s Hospital, a large tertiary academic children’s hospital, to perform a pre-post analysis around the introduction of the ICID service in July 2019. The service includes a single full-time equivalent advanced practice provider and a subset of ~6 physicians whose clinical time is dedicated to ICID. The pre-intervention period included data from 2015-2019 and the post-intervention period included data from 2019-2023. A pre-existing database of patients receiving solid organ or stem cell transplantation was available for review of infectious diseases involvement. Antimicrobial use data was extracted from the EHR and normalized to days of therapy (DOT) per 1000 patient days. Antimicrobial DOT were trended for the three units that utilize the ICID service most frequently: hematology/oncology, cardiology, and the pediatric intensive care unit (PICU). Results Over the first four years of implementation (2019-2023), total annual consults doubled from 203 to 429. After normalizing for hospital volume, there was a similar increase from 2.2 consults per 1000 patient days to 3.9 consults per 1000 patient days. A decrease in broad-spectrum antimicrobial DOT was observed following implementation. There was an overall decrease in the anti-pseudomonal DOT for all three units (p≤.046), including a significant decrease meropenem usage (p≤.033). Reduction in resistant Gram-positive DOT was primarily driven by decreased vancomycin use seen in the cardiology group (p<.001). In the post-intervention timeframe, the hematology/oncology group was noted to be using significantly less voriconazole (p=.005) with increased micafungin use (p<.001). Implementation of the ICID service was also associated with improved HSCT one year survival when analyzing all-cause (p=.023) and infection-attributable mortality (p=.019). Conclusion Implementation of an ICID service led to increased engagement in the care of IC patients, an overall decrease in the use of broad-spectrum antimicrobials and improved mortality in HSCT patients. Our data provides deeper insights into the impact of an ICID service and how it contributes to the optimization of care in a complex patient population who are routinely exposed to broad spectrum antimicrobials. Future multi-centered studies are needed to validate the effects of ICID care on the outcomes of IC individuals and the effect on antimicrobial usage.