Impact of a New Diagnostic Stewardship Team on Utilization and Interpretation of a Microbial Cell-Free DNA Detection Test
Authors: Goggin Kathryn P , Fox Thomas G , Jaggi Preeti , Shane Andi L , Gonzalez Mark D 
Published: November 2023

Abstract

Background
After commercial metagenomic next-generation sequencing of plasma microbial cell-free DNA (NGS-mcfDNA) became available at Children’s Healthcare of Atlanta (CHOA) in 2018 with an institutional requirement for Infectious Disease (ID) consultation and approval, we observed an initial period of test utilization without consistent ID involvement. Subsequently we assembled a Diagnostic Stewardship Team (DST) composed of a clinical microbiologist and 3 ID clinicians with expertise in diagnosis and management of infections in immunocompromised children and antimicrobial stewardship, to improve test utilization by clinicians and to optimally impact patient care.

Methods
We performed a retrospective medical record review as an IRB-deemed Quality Improvement project. NGS-mcfDNA results and their clinical impacts prior to the formation of the DST were assessed, using previously published standardized criteria as an initial framework (Hogan 2021)1. We shared our findings with Bone Marrow Transplant (BMT), Pediatric Intensive Care Unit (PICU), and ID clinicians, providing education on the potential benefits and limitations of NGS-mcfDNA testing. Stakeholder acceptability and engagement with the DST was prioritized, with emphasis on highlighting the benefits to clinicians of expertise in patient selection for testing and with interpretation of results which can be discordant with conventional microbiological tests. DST approval became required for all NGS-mcfDNA tests, with approval decision and discussion documented in the medical record, followed by documentation of test results, interpretation, and communications with treating and consulting clinicians. After one year of DST engagement, which began on June 1, 2021, we repeated our analysis of NGS-mcfDNA utilization and clinical impacts to evaluate the results of DST involvement. We classified time periods into pre-DST, February 28, 2018 - April 12, 2021, and post-DST, June 1, 2021 – May 31, 2022.

Results
The majority of NGS-mcfDNA tests sent in both the pre- and post-DST periods resulted in no or indeterminate clinical impact (65% pre-DST vs. 73% post-DST), while post-DST the percentage of positive clinical impacts increased (18% pre-DST vs. 25% post-DST), and the percentage of negative clinical impacts decreased (16% pre-DST vs. 2% post-DST), likely due to DST engagement. The number of tests per year increased by three-fold, while fewer patients had multiple NGS-mcfDNA tests sent. Awareness of the requirement for DST consultation and test approval lead to more selective NGS-mcfDNA test requests on the part of BMT clinicians, and the majority of positive clinical impacts from NGS-mcfDNA testing in BMT patients resulted from collaboration between BMT and ID in de-escalation of antimicrobials. An increased awareness of the potential benefits of NGS-mcfDNA testing for pre-treated and diagnostically challenging patients led to an increase in NGS-mcfDNA test requests from ID clinicians.

Conclusion
Implementation of a DST resulted in universal ID engagement with clinicians requesting NGS-mcfDNA tests and ID involvement in test interpretation. Discussion with experienced diagnostic stewards at the time of NGS-mcfDNA test consideration, with attention to the rationale for test request and consideration of potential test limitations prior to return of results, in addition to rigorous interpretation of results, can increase the positive clinical impacts and decrease the negative clinical impacts of NGS-mcfDNA tests.

Reference
1. Hogan CA, Yang S, Garner OB, Green DA, Gomez CA, Dien Bard J, Pinsky BA, Banaei N. Clinical Impact of Metagenomic Next-Generation Sequencing of Plasma Cell-Free DNA for the Diagnosis of Infectious Diseases: A Multicenter Retrospective Cohort Study. Clin Infect Dis. 2021 Jan 27;72(2):239-245. doi: 10.1093/cid/ciaa035. PMID: 31942944.
Characteristics of NGS-mcfDNA tests sent from CHOA

NGS-mcfDNA tests in BMT patients post-DST (n=19 tests)