Non-Linear Threshold Effect of Dynamic Estimated Plasma Volume Status on Revealing In-Hospital Mortality Risk in Sepsis.

This retrospective cohort study evaluated the association between estimated plasma volume status (ePVS) and in-hospital mortality in adult patients with sepsis from the MIMIC-IV (v2.2) database. After excluding patients with early death, readmission, red blood cell transfusion, malignancy, or missing ePVS data, 17,403 patients meeting Sepsis-3 criteria were included. ePVS was calculated using hemoglobin and hematocrit. Early ePVS (ePVS1), late-ICU ePVS (ePVS2), and ePVS change were analyzed using multivariable logistic regression, restricted cubic splines, threshold analysis, prediction metrics, Kaplan-Meier analysis, subgroup analysis, and sensitivity analyses. In-hospital mortality was 13.2%. ePVS2 and ePVS change were significantly higher in non-survivors, whereas the difference in ePVS1 was small. After adjustment, ePVS2 (adjusted odds ratio [OR] = 1.14, 95% confidence interval [CI]: 1.11-1.18, p < 0.001) and ePVS change (adjusted OR = 1.04, 95% CI: 1.02-1.05, p < 0.001) remained independently associated with in-hospital mortality, while ePVS1 was not significant. Non-linear and threshold analyses suggested lower risk at ePVS2 of approximately 6-8 dL/g and ePVS change of -4.5 to 2, with increased risk at ePVS2 ≥ 8 dL/g or ePVS change ≥ 2. Late-ICU ePVS2 and ePVS change may supplement volume-status assessment and short-term prognostic stratification in sepsis, but prospective validation is needed.