Predictive Value of APACHE II, Extravascular Lung Water Index, and Total Bilirubin for 28-Day Mortality in Mechanically Ventilated Septic Patients

Abstract This retrospective case-control study enrolled 119 adult septic patients on MV from March 2023 to October 2024 . Among the 119 enrolled patients, 36 (30.3%) died within 28 days of MV. Multivariate logistic regression identified the following independent risk factors for 28-day mortality: Acute Physiology and Chronic Health Evaluation II(APACHE II) score (OR = 1.115, 95% CI: 1.033–1.204, P = 0.005), Extravascular Lung Water Index (EVLWI) (OR = 1.157, 95% CI: 1.053–1.272, P = 0.003), and Total bilirubin (Tbil) (OR = 1.025, 95% CI: 1.005–1.045, P = 0.014). A predictive model combining APACHE II, EVLWI, and Tbil demonstrated high efficacy, with an area under the curve (AUC) of 0.793, sensitivity of 52.8%, and specificity of 97.6%. Kalan-Meier analysis revealed significantly lower survival rates in patients with high APACHE II scores, elevated EVLWI, or elevated Tbil compared to those with lower levels. Multivariate Cox regression confirmed that high Tbil (HR = 2.887, 95% CI: 1.459–5.713, P = 0.002), high APACHE II scores (HR = 2.972, 95% CI: 1.534–5.757, P = 0.001), and high EVLWI (HR = 3.546, 95% CI: 1.250–10.061, P = 0.017) were independently associated with increased mortality risk. The results highlight APACHE II score, EVLWI, and Tbil are critical predictors of 28-day prognosis in septic patients with mechanical ventilation.