Diagnostic Accuracy of Biomarkers for Microaspiration in Mechanically Ventilated Patients: A Systematic Review

This systematic review and meta-analysis evaluates the diagnostic accuracy of biomarkers for detecting microaspiration and predicting Ventilator-Associated Pneumonia (VAP) in mechanically ventilated adults. While microaspiration is a key pathogenic mechanism, identifying reliable diagnostic markers remains challenging due to heterogeneity in study designs and reference standards. To address these methodological limitations, this study adopts a conditional synthesis strategy: Quantitative Synthesis (Meta-Analysis): A meta-analysis will be performed for biomarkers where sufficient homogenous data are available to support statistical pooling (e.g., Airway Amylase). For these analyses, inclusion will be strictly restricted to studies utilizing a confirmed clinical VAP reference standard to ensure prognostic validity. Subgroup analyses will be conducted to investigate the impact of specimen matrix (e.g., Mini-BAL vs. Tracheal Aspirate) on diagnostic accuracy and heterogeneity. Qualitative Synthesis (Systematic Review): For biomarkers where data are insufficient for pooling, or where studies rely on physiological proxies (e.g., Pepsin, Blue Dye tests, FEES) rather than clinical outcomes, a comprehensive narrative synthesis will be conducted. These studies will be critically appraised for biological plausibility but excluded from meta-analysis to avoid incorporation bias and ensure clinical homogeneity. This review aims to provide an updated, rigorously stratified assessment of microaspiration biomarkers, determining which candidates offer robust diagnostic utility for clinical practice.