Objective:

To evaluate the diagnostic and prognostic performance of the Leukocyte ImmunoTest (LIT) in distinguishing infection and sepsis from non-infectious conditions.

Approach:

• Study Design: A prospective observational study conducted in intensive care and internal medicine wards of a university hospital.
• Participant Groups: Participants were categorized into three groups: inpatient controls (n=29), infection (n=47), and sepsis (n=106).
• Testing Method: LIT was performed on whole blood samples, measuring neutrophil ROS production in relative light units (RLU).
• Comparative Analysis: LIT results were compared with C-reactive protein (CRP), procalcitonin (PCT), white blood cell count (WBC), and neutrophil count (PMNL).
• Performance Evaluation: Diagnostic performance was assessed using receiver operating characteristic (ROC) analysis.

Key Findings:

• Median LIT values increased across diagnostic groups: 470 RLU in controls, 882 in infection, and 2466 in sepsis (adjusted p < 0.05).
• LIT demonstrated good diagnostic performance for infection (AUC: 0.94, 95% CI: 0.911–0.968) and sepsis (AUC: 0.86, 95% CI: 0.795–0.915).
• Higher LIT values were independently associated with increased mortality (HR:1.6, 95% CI:1.2–2.2; p=0.005).

Interpretation:

LIT is a rapid bedside immune assay that captures neutrophil activation dynamics.

Limitations:

• The study was conducted in a single center, limiting generalizability.
• Further multicenter studies are needed to confirm findings and clarify LIT's role in sepsis management.

Conclusion:

LIT may serve as a complementary biomarker in sepsis management, warranting further investigation.