P-2247. Comparison of a Cellular Host-Response Test to Blood Culture Results for Risk Stratification and Diagnosis of Sepsis
Authors: Sorrells Matt , Sheybani Roya , Shah Ajay M , O’Neal Hollis R , Scoggins Robert 
Published: January 2025

Abstract

Background
Sepsis is a life-threatening syndrome that requires urgent intervention to achieve optimal outcomes[1-3]. While considered the gold standard for bacteremia and sepsis diagnosis, blood cultures (BCX) require long turnaround and offer low sensitivity [4], with only 18-25% of patients with sepsis returning positive BCXs [5]. In this study, we compared a cellular host response test to BCX in performance for diagnosing and risk-stratifying patients suspected of sepsis in the ED.
Figure 1
Rate of sepsis status, per Sepsis-3 definition, across HR interpretation bands (A) and blood culture results (B). 28-day survival probability for in-hospital infection associated mortality for (C) HR interpretation bands and (D) blood culture results. * and **** represent p &lt; 0.05 and p &lt; 0.0001, respectively.

Methods
A semi-quantitative in-vitro cellular host-response test (HR) uses deformability cytometry to assess leukocyte biophysical properties from whole blood in &lt; 10 min. The test generates an Index based on increasing WBC deformability, stratified into 3 interpretation bands (Band 1, Band 2, Band 3) of increasing sepsis likelihood [6].
Adult patients presenting to the ED with signs or suspicion of infection were prospectively enrolled at multiple US sites (02/2016–10/2021). EDTA-anticoagulated blood was assayed 5 hours from draw using the test, and patients were followed by retrospective chart review. Infection and sepsis status was determined via retrospective physician adjudication per Sepsis-3, during which adjudicators were blinded to HR results but had BCX results visible.
Table 1
Sepsis-3 receiver operator characteristic diagnostic performance for HR compared to blood culture results.

Results
Our cohort of 490 patients for whom BCXs were ordered was stratified into 175 Band 1, 129 Band 2, and 186 Band 3 patients for HR versus 385 BCX+ and 105 BCX- patients. When evaluated for diagnostic performance for Sepsis-3, HR, compared to BCX, yielded higher AUC (0.82 [0.78 - 0.86 95% CI] HR vs. 0.7 [0.66 - 0.74] BCX), higher sensitivity (93.2% HR vs 46.9% BCX), and higher negative predictive value (93.1% HR vs 75.6% BCX) with similar specificity (82.1% [75.4 - 87.3%] HR vs 93.0% [87.8 - 96.0%] BCX) and positive predictive value (68.5% [61.0 - 75.1%] HR vs 79.0% [71.4 - 84.3%] BCX,Fig. 1 A/B, Tab. 1). For infection-associated mortality, survival rates of 100% (N = 35 surv. /35 inf.) and 87.1% (N = 122 surv. /140 inf.) were found for Bands 1 & 3, respectively (p &lt; 0.05) compared 93.1% (N = 135 surv. / 145 inf.) and 89.1% (N = 82 survived /92 infected) for BCX - & +, respectively (p &gt; 0.05).
References

Conclusion
These findings indicate that the HR test may provide more accurate and timely results for sepsis diagnosis and risk stratification when compared to BCX.

Disclosures
Matt Sorrells, PhD, Cytovale Inc.: Employee Roya Sheybani, PhD, Cytovale Inc.: Employee Ajay M. Shah, PhD, Cytovale Inc.: CEO Robert Scoggins, MD, PhD, Cytovale Inc.: Employee, CMO