Abstract
We aimed to explore the association of hyperkalemia and short- and mid-term mortality in critically ill patients using the Medical Information Mart for Intensive Care (MIMIC-IV) database. Adult patients who had been stayed in the intensive care unit (ICU) for at least 48 h and tested for serum potassium were included. Hyperkalemia was defined as serum potassium higher than 5.5 mmol/L. Exposures included the occurrence the timing of hyperkalemia and the numeric values of serum potassium. The outcomes included ICU mortality and 7 days and 30 days mortality after ICU admission. Survival curves were calculated according to Kaplan-Meier analysis. Univariate and multivariate Cox proportional hazard regression models were used to estimate the hazard ratio (HR) and 95% confidence interval (CI) of each exposure for the outcomes. Subgroup analyses after full adjustment were conducted. A total of 22,370 ICU patients were included in this study. The prevalence of hyperkalemia was 18.8%. Patients with and without hyperkalemia differed significantly in a number of baseline characteristics. The ICU mortality, 7 days mortality, and 30 days mortality rates in the overall population were 12.6%, 9.5%, and 19.1%, respectively. After full adjustment, the occurrence of hyperkalemia is closely associated with the ICU mortality (HR: 1.39; 95% CI: 1.22-1.58) and 30 days mortality (HR: 1.16; 95% CI: 1.03-1.31) of the ICU patients. The timing of hyperkalemia is also associated with the risk of mortalities. These associations remained unchanged in the multiple regression analysis after full adjustment for the demographic variables, clinical tests, and comorbidities. In conclusion, the occurrence and timing of hyperkalemia are closely associated with the ICU and 30 days mortalities of critically ill patients. Once hyperkalemia occurs, active interventions are needed to restore serum potassium levels, regardless of the numeric values, to normal as quickly as possible.