Early High-Protein Enteral Nutrition in Mechanically Ventilated Intensive Care Unit Patients: A Propensity-Matched Retrospective Cohort Study

Objectives: This study aimed to evaluate whether early (≤48 hours) high-protein enteral nutrition (EN) (≥1.5 g/kg/day) is associated with improved clinical outcomes compared with standard-protein EN (<1.2 g/kg/day) in mechanically ventilated intensive care unit (ICU) patients.Methods: A retrospective cohort study was conducted in a tertiary ICU between 2022 and 2025.Adult mechanically ventilated cases receiving EN for ≥five days (n=450) were included.Exposure was early highprotein EN versus standard-protein EN.The primary outcome was ventilator-free days (VFDs) at 28 days.Propensity score matching (1:1) was used to adjust for baseline severity, followed by multivariable regression.Results: After matching, 180 patients per group were analysed.Early high-protein EN was associated with more VFDs (mean 18.2 vs. 14.5 days; p=0.003), shorter ICU stay (median 9 vs. 12 days; p=0.008), and lower delirium incidence (24% vs. 38%; p=0.002).No difference in 28-day mortality (21% vs. 25%; p=0.18) was observed.The benefit was greatest in malnourished patients (Prognostic Nutritional Index (PNI) <38; VFD difference 5.2 days; p=0.001).Conclusion: Early high-protein EN in mechanically ventilated ICU patients was associated with shorter ventilation duration, reduced ICU stay, and lower delirium risk, particularly in malnourished patients.However, given the retrospective observational design, these findings demonstrate associations rather than causal benefits.Prospective randomised controlled trials are required to confirm whether early high-protein delivery independently improves critical care recovery before definitive clinical recommendations can be made.