Prognostic Impact of Overhydration in Hospitalized Patients Receiving Parenteral Nutrition

Background & Aims: Accurate assessment of hydration status is particularly relevant in hospitalized patients receiving parenteral support in whom fluid disturbances are common and may be associated with adverse outcomes. However, the prognostic significance of bioimpedance-derived hydration status in the population receiving parenteral nutrition (PN) remains poorly defined. This study aimed to evaluate the association between hydration status at the beginning of PN and in-hospital mortality. Methods: This single-center prospective observational cohort included hospitalized adults receiving PN between November 2024 and March 2026. Hydration status was assessed within 72 h of PN initiation using bioelectrical impedance analysis (Hydragram®, Akern). Receiver operating characteristic (ROC) analysis was used to identify the optimal hydration threshold for in-hospital mortality prediction. Survival was evaluated using Kaplan–Meier analysis and Cox proportional hazards models. Results: A total of 276 patients were included (62.0% male; mean age 64.9 ± 17.5 years). Overall in-hospital mortality was 13.4%. Hydration percentage showed good discrimination for in-hospital mortality (AUC 0.776, 95% CI 0.672–0.880; p < 0.001), with an optimal cut-off value of 79.45%. Patients with overhydration exhibited higher mortality rates than normohydrated patients (29.3% vs. 5.4%; log-rank p < 0.001). In multivariable Cox regression analysis, overhydration remained independently associated with in-hospital mortality (HR 2.85, 95% CI 1.21–6.70; p = 0.016), together with age (HR 1.06, 95% CI 1.02–1.10; p = 0.002). Bioelectrical impedance vector analysis (BIVA) demonstrated a clustering of non-survivors in vector regions consistent with extracellular fluid expansion. Conclusions: Overhydration assessed by bioelectrical impedance analysis was independently associated with in-hospital mortality in patients receiving PN. Early assessment of hydration status by bioelectrical impedance may provide clinically relevant information for risk stratification in hospitalized patients receiving parenteral nutrition.