Association between hydration status and mortality in elderly obese critically ill patients with acute kidney injury: A retrospective cohort study

ObjectivesFluid management in critically ill obese patients is challenging due to the risk of fluid overload when using standard weight-based formulas. This study aims to evaluate the association between hydration status and mortality in elderly obese critically ill patients with acute kidney injury (AKI).MethodsThis retrospective cohort study included elderly obese critically ill patients with AKI admitted to a tertiary care ICU between January 2020 and December 2022. AKI was diagnosed according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Fluid overload was defined as body weight-adjusted fluid balance >10%. The primary outcome was 90-day all-cause mortality. Statistical analyses included Kaplan-Meier survival curves and multivariate Cox regression.ResultsA total of 539 elderly obese critically ill patients with AKI were included, of whom 244 (45.3%) developed fluid overload. During the 90-day follow-up, 209 patients (38.8%) died. Patients with fluid overload had significantly higher 90-day mortality compared to those without fluid overload (50.4% vs. 29.2%, <i>P</i> < 0.01). Kaplan-Meier analysis showed a higher mortality risk for fluid-overloaded patients (<i>P</i> < 0.01). Multivariate Cox regression indicated that fluid overload (HR = 2.04, 95% CI: 1.24-3.36, <i>P</i> < 0.01) and SOFA score (HR = 1.13, 95% CI: 1.04-1.22, <i>P</i> < 0.01) were independent predictors of increased mortality.ConclusionsFluid overload is significantly associated with increased 90-day mortality in elderly obese critically ill patients with AKI.