Group-based Trajectory Modeling of Serum Sodium and Survival in Sepsis Patients with Lactic Acidosis: Results from MIMIC-IV Database.

The purpose of this project was to characterize the longitudinal dynamic serum sodium trajectory of sepsis patients with lactic acidosis (LA) admitted to the intensive care unit (ICU), and to explore the association between these trajectories and the 30-day mortality rate of patients. Data on patients admitted to the ICU with a diagnosis of LA combined with sepsis from 2008-2019 were collected from the Medical Information Mart for Intensive Care-IV (MIMIC-IV) database. Patients admitted to the ICU for > 24 hours and for the first time were sorted into 3 groups based on their serum sodium levels at admission. The Group-based Trajectory Modeling (GBTM) method was applied to analyze the trajectory changes of serum sodium in each group of patients over 72 hours. Patients' survival differences between different trajectory groups were compared using Kaplan-Meier (K-M) survival curves. Subgroup analysis was carried out to determine the influencing factors of the relationship between dynamic changes in serum sodium and patient survival. This study included 514 patients with LA complicated by sepsis, who were clustered into three groups based on their admission serum sodium levels, with 378 patients in the normal blood sodium (135-145 mEq/L) group, 116 patients in the hyponatremia (< 135 mEq/L) group, and 20 patients in the hypernatremia (> 145 mEq/L) group. GBTM analysis generated three different serum sodium trajectories. The K-M curve results demonstrated that patients with relatively stable serum sodium levels within the normal range (Class 2) had lower 30-day mortality compared to groups with larger fluctuations in sodium levels (Class 1, Class 3). Subgroup analysis uncovered notable interactions (P < 0.05) between different trajectories of serum sodium and covariates such as race, marital status, Glasgow Coma Scale (GCS), Sequential Organ Failure Assessment (SOFA), renal replacement therapy (RRT), congestive heart failure, kidney disease, liver disease, and diabetes. Among patients with LA complicated by sepsis, those with stable and normal fluctuations in serum sodium levels had better 30-day survival rates. GBTM is a refined method to describe the evolution of serum sodium and its association with clinical outcomes, which may enhance the current understanding of blood sodium level regulation.