879. Host Response Classifiers Identify Infection and Illness Severity and Improve Antibiotic Decision-Making in Patients with Suspected Infections Presenting to the Emergency Department

Nonspecific presentation and limited diagnostic solutions of acute infections and sepsis in emergency departments (EDs) result in early antimicrobial administration at a cost to antimicrobial stewardship. We validated the host response classifiers, IMX-BVN-3b and SEV-3b, to determine bacterial and viral infection status and illness severity. We also assessed antibiotic over- and underuse.

We prospectively enrolled adult ED patients with suspected acute infections or sepsis with ≥1 vital sign abnormal across 7 sites. At enrollment, we surveyed treating physicians on infection probability and antibiotic prescribing. BVN/SEV-3b were calculated using NanoString nCounter® on PAXgene® blood samples. We compared BVN-3b likelihood of bacterial and viral infection to post-hoc clinical adjudication infection status and SEV-3b likelihood of severe outcomes to 7-day need for ICU care and 30-day mortality.

Of 568 enrolled patients, 346 had consensus adjudications (131 bacterial, 52 viral, 1 coinfection, 162 noninfected). The BVN-3b area under the receiver operating curve (AUROC) for bacterial infections was 0.82 (95%CI 0.77-0.87), compared to 0.76 (95%CI 0.71-0.81) for procalcitonin (p = 0.011). BVN-3b AUROC for viral infections was 0.89 (95%CI 0.84-0.95). SEV-3b AUROC was 0.78 (95%CI 0.69-0.86) and 0.88 (95%CI 0.73-1) for 7-day ICU care and 30-day mortality, respectively. Of the 346, 226 patients had a pre-lab result physician questionnaire; of these, 110 patients received antibiotics. Of these, BVN-3b would have corrected 71% of antibiotic prescribing errors (34/48 overprescriptions and 13/18 underprescriptions).

BVN-3b and SEV-3b accurately identified bacterial and viral infections and risk status. If implemented in a rapid workflow, these tests may improve patient management and antibiotic prescribing, reducing healthcare costs in the ED.

Arianna Beltran, BS, Inflammatix: Internship Uan-I Chen, MS, Inflammatix: Stocks/Bonds Edward A. Michelson, MD, Inflamatix: Research expense reimbursement for sponsored clinical trial Alexandra Weissman, MD, Inflammatix Inc: Advisor/Consultant Evangelos J. Giamarellos-Bourboulis, PhD, D(ABMM), Abbot Product Operations AG: Grant/Research Support|Abbot Product Operations AG: Honoraria|bioMerieux: Grant/Research Support|bioMerieux: Honoraria|Horizon 2020 European Program: Grant/Research Support|Horizon Health European Program: Grant/Research Support|Sobi AB: Advisor/Consultant|Sobi AB: Grant/Research Support|Sobi AB: Honoraria Oliver Liesenfeld, MD, Inflammatix Inc.: Ownership Interest Natalie N. Whitfield, PhD, D(ABMM), GenMark Dx/Roche: Employee|GenMark Dx/Roche: Stocks/Bonds|Inflammatix: Employee|Inflammatix: Stocks/Bonds