Elevated serum osmolarity is associated with 28-day all-cause mortality in patients with cardiac arrest

BACKGROUND: Serum osmolality is a prognostic indicator in critically ill patients.This study aimed to evaluate the association between high osmolality and 28-day mortality in patients with cardiac arrest (CA) admitted to the intensive care unit (ICU).METHODS: Baseline data of adult patients with CA who were admitted to the ICU from 2008 to 2019 were collected from the Medical Information Mart for Intensive Care (MIMIC)-IV.Patients were divided into survivor and non-survivor groups according to the 28-day prognosis.Serum concentrations of sodium, potassium, glucose, and urea nitrogen were used to determine serum osmolarity.The primary endpoint of this study was 28-day all-cause mortality.Propensity score matching (PSM) analysis was performed to reduce bias between the survivor and non-survivor groups.RESULTS: Among the 798 included CA patients, the high osmolarity remained signifi cantly associated with increased 28-day mortality (62.0% vs. 35.5%,P<0.001) and reduced cumulative survival (log-rank P<0.05) after PSM.Cox regression identified the high osmolarity as an independent predictor.The serum high osmolarity on days 1, 3, 7, and 28 of ICU admission had predictive values for 28-day all-cause mortality (all P<0.05) before PSM and after PSM, but the serum high osmolarity on day 1 of ICU admission had the biggest AUC for predicting 28-day all-cause mortality before PSM and after PSM (all P<0.05).CONCLUSION: Elevated serum osmolarity may be independently associated with increased 28-day mortality in CA patients and could serve as a prognostic marker.