[Association of serum potassium trajectory with 30-day death risk in patients with sepsis in intensive care unit: a retrospective cohort study].

Objective: To investigate the relationship between the trajectories of serum potassium changes after intensive care unit (ICU) admission and 30-day death risk in patients with sepsis.

Methods: A retrospective cohort study was conducted, including adult patients with sepsis admitted to the comprehensive ICU, medical intensive care unit (MICU) and emergency intensive care unit (EICU) of Guizhou Medical University Affiliated Hospital from January 2020 to January 2024. The patients who had a minimum of 5 days' hospitalisation in the ICU and who had at least 7 consecutive days of the serum potassium measurements were classified into five trajectories groups according to group-based trajectory modelling (GBTM) using SAS software. This was based on tendency changes in serum potassium levels in patients after admission to the ICU, which was categorized as follows: slowly increased from a low level group, slowly increased from a medium level of normal range group, slowly decreased from a medium level of normal range group, slowly decreased from a high level group, and slowly increased from a high level of normal range group. The patient's gender, age, medical history, and white blood cell count (WBC), platelet count (PLT), procalcitonin (PCT), activated partial thromboplastin time (APTT), prothrombin time (PT), blood sodium, and serum creatinine (SCr) at the time of admission to the ICU were collected. At the same time, the patient's worst sequential organ failure assessment (SOFA) score within 24 hours of admission to the ICU, length of ICU stay, and 30-day outcome were record. The differences in clinical data among different groups of patients were compared. The 30-day cumulative survival rates of the various serum potassium trajectories were plotted using Kaplan-Meier survival curves, the groups were then compared using the Log-Rank test. A multivariate Cox proportional risk regression analysis was developed to evaluate the independent effect of serum potassium trajectory on 30-day death risk.

Results: Finally, 342 ICU sepsis patients were enrolled, of which 42 patients in the slowly increased from a low level group (12.28%), 127 patients in the slowly increased from a medium level of normal range group (37.14%), 118 patients in the slowly decreased from a medium level of normal range group (34.50%), 28 patients in the slowly decreased from a high level group (8.19%), and 27 patients in the slowly increased from a high level of normal range group (7.89%). Except for age and APTT differences, there were no statistically significant differences in other clinical characteristics among the patients in the different serum potassium trajectories groups. Kaplan-Meier survival curves showed that there was statistically significant difference in the 30-day cumulative survival rate among the patients in the different serum potassium trajectories groups (Log-Rank test: χ² = 14.696, P = 0.005), with the lowest in the slowly increased from a high level of normal range group (39.3%). Multivariate Cox proportional risk regression analysis showed that the patients with the serum potassium trajectory of slowly increased from a high level of normal range had the highest 30-day death risk [hazard ratio (HR) = 2.341, 95% confidence interval (95%CI) was 1.049-5.226, P = 0.038]. This association persisted after adjustment for variables such as gender, age, medical history, SOFA score, WBC, PLT, PCT, APTT, PT, blood sodium, and SCr (HR = 3.058, 95%CI was 1.249-7.488, P = 0.014).

Conclusion: Compared with the patients whose serum potassium fluctuated within the normal range, the sepsis patients in the ICU with a serum potassium trajectory that slowly increased from a high level of normal range had a significantly higher 30-day death risk.