# Biomarker-based diagnosis of ventilator-associated pneumonia using serum and bronchoalveolar lavage fluid levels of presepsin, procalcitonin, and lipopolysaccharide-binding protein

## TL;DR

This study shows that analyzing biomarkers in bronchoalveolar lavage fluid may improve the diagnosis of ventilator-associated pneumonia in ventilated patients.

## Contribution

The study compares serum and bronchoalveolar lavage fluid biomarkers for VAP diagnosis and highlights the superior diagnostic value of BALF.

## Key findings

- Serum and BALF levels of presepsin, PCT, and LBP were higher in confirmed VAP cases.
- Combining BALF presepsin and LBP showed the highest diagnostic accuracy (AUC of 0.92).
- BALF biomarkers outperformed serum biomarkers for VAP diagnosis.

## Abstract

Mechanically ventilated patients are often confronted with ventilator-associated pneumonia (VAP), showing an increased risk of mortality. Early identification of biomarkers associated with VAP may ease the diagnosis and guide preventive interventions. In this study, we investigated the diagnostic value of VAP using serum and bronchoalveolar lavage fluid (BALF) levels of presepsin, procalcitonin (PCT), and lipopolysaccharide-binding protein (LBP).

The serum and BALF samples were collected from 300 consecutive mechanically ventilated patients with a clinical suspicion of VAP by bronchoscopy. Among these 300 patients, 126 patients had confirmed VAP, while 174 did not meet the criteria for VAP.

The reference ranges of serum presepsin, PCT, and LBP in patients with confirmed VAP were all higher than those in patients with VAP criteria not fulfilled (p < 0.0001). The reference ranges of BALF presepsin and LBP were both higher in patients with confirmed VAP than those in patients with VAP criteria not fulfilled (p < 0.0001), whereas the reference range of BALF PCT did not differ between the two groups (p = 0.202). Subgroup analysis based on main pathologies found higher levels of serum LBP, BALF presepsin, and LBP in the gram-negative group than in the gram-positive group (p < 0.001). Serum levels of presepsin, PCT, and LBP for VAP diagnosis presented AUC values of 0.81, 0.76, and 0.78, respectively. Combined analysis of serum presepsin and LBP for the diagnostic evaluation of VAP showed an AUC of 0.88, and combined analysis of the three serum levels for the diagnostic evaluation of VAP showed an AUC of 0.90. The BALF levels of presepsin and LBP for VAP diagnosis presented AUC values of 0.85 and 0.84, respectively. Combined analysis of the two BALF levels for the diagnostic evaluation of VAP showed an AUC of 0.92. Combining BALF levels of presepsin and LBP may yield better diagnostic value for the development of VAP in mechanically ventilated patients than serum.

Our findings point to the importance of selecting the correct biological fluid when analyzing molecular diagnostics for definitive VAP among mechanically ventilated patients with suspicion of VAP.