Clinical Utility of Positive End-expiratory Pressure-incorporated PaO2/FiO2 Ratio in Prognosticating Mortality and Severity Reclassification in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-analysis

Introduction: PaO 2 /FiO 2 (PF) ratio is globally used for defining and classifying acute respiratory distress syndrome (ARDS), yet it does not take ventilatory support into consideration, which is crucial in achieving oxygenation.Incorporating the positive end-expiratory pressure (PEEP) into the PF ratio (PaO 2 /FiO 2 *PEEP; PFP ratio) may provide a more physiologically meaningful index of disease diagnosis, severity, and prognosis.Objectives: To evaluate the clinical utility of the PFP ratio in prognosticating mortality and its impact on reclassification of ARDS severity as compared to the traditional PF ratio.Materials and methods: This systematic review and meta-analysis (SRMA) was performed following PRISMA guidelines and registered in PROSPERO (CRD420251110685).A search for relevant studies from inception to July 2025 was performed, and the studies on adults with ARDS receiving invasive mechanical ventilation (IMV) and those that reported PFP ratio and mortality outcomes were included.Summary receiver operating characteristic (sROC) model was used to evaluate the prognostic accuracy, while the reclassification of ARDS severity using PFP vs PF ratio was descriptively analyzed.Results: A total of five studies with 4,454 patients were included for meta-analysis.The pooled sensitivity and specificity of the PFP ratio for prognosticating mortality were 0.55 [95% confidence interval (CI): 0.41-0.67]and 0.90 (95% CI: 0.80-0.96),respectively.The area under the sROC was 0.84 (95% CI: 0.80-0.85),inferring good discriminant ability.For reclassification of ARDS severity based on PFP ratio, a total of four studies were included, and 30-71.9% of patients were reclassified, showing significant bidirectional shifts.Conclusion: Positive end-expiratory pressure incorporation to the PF ratio improves the prognostic ability and leads to meaningful reclassification of ARDS severity.