Positive Fluid Overload Is Associated with Worse Clinical Outcomes in Critically Ill Patients: An Updated Meta-Analysis of Observational Studies

Abstract

Context: Critically ill patients in the intensive care unit (ICU) often experience or are at high risk of organ failure. Fluid administration is a routine and essential intervention aimed at restoring and maintaining tissue perfusion and meeting daily physiological needs. However, due to altered physiology, these patients are susceptible to fluid overload (FO), which has been associated with poor clinical outcomes. Objectives: This meta-analysis aimed to refine and strengthen the evidence for the association between FO or positive cumulative fluid balance (CFB) and mortality, based on observational studies published over the past decade. Data Sources: A systematic literature search was conducted across PubMed, EuropePMC, ScienceDirect, and Google Scholar for studies published between 2013 and September 2023. Observational studies investigating FO or positive CFB in critically ill adult patients were included. Adjusted pooled effect estimates were reported as risk ratios (RRs). Results: A total of 34 observational studies involving 49,467 participants met the inclusion criteria. Fluid overload ≥ 10% from baseline was associated with an increased risk of 30-day mortality [RR: 1.47 (95% CI: 1.06 - 1.89)]. Similarly, a positive 72-hour CFB was linked to higher mortality [RR: 1.29 (95% CI: 1.14 - 1.44)]. Each 1-liter increase in CFB was also significantly associated with increased risk [RR: 1.16 (95% CI: 1.01 - 1.33); I2 = 77.87%, p-heterogeneity = 0.019]. Furthermore, 72-hour positive CFB was strongly associated with 90-day mortality [RR: 1.91 (95% CI: 1.49 - 2.32)]. Conclusions: This updated meta-analysis confirms that FO and positive CFB are significantly associated with increased mortality in critically ill patients. These findings underscore the importance of fluid management strategies in the ICU to improve clinical outcomes.