Dyskalaemia as a predictor of mortality in sepsis: a retrospective cohort study.

Objectives: To evaluate the association between dyskalaemia and 30-day mortality in patients with sepsis and to determine whether potassium disturbances serve as independent prognostic markers in this population.

Methods: This retrospective cohort study included adult patients diagnosed with sepsis who were admitted to the emergency department of a tertiary hospital between January 1, 2022, and January 1, 2025. Serum potassium levels at admission were categorized as hypokalemia (< 3.5 mmol/L), normokalemia (3.5-5.0 mmol/L), and hyperkalemia (> 5.0 mmol/L). The primary outcome was 30-day all-cause mortality. Multivariate logistic regression was used to identify independent predictors of mortality, adjusting for confounders. A restricted cubic spline regression model was applied to assess the non-linear relationship between potassium levels and mortality.

Results: A total of 1,347 patients were included, of whom 305 (22.6%) died within 30 days. Both hypokalemia and hyperkalemia were significantly associated with increased mortality compared to normokalemia. Dyskalaemia was independently associated with mortality (OR = 2.10, 95% CI: 1.45-3.05, p < 0.001), and a U-shaped relationship was observed between potassium levels and mortality risk. The predictive model demonstrated good calibration (Hosmer-Lemeshow test, p = 0.584) and discrimination (AUROC = 0.840, 95% CI: 0.788-0.879).

Conclusions: Dyskalaemia was identified as an independent predictor of 30-day mortality in septic patients. These findings highlight the clinical relevance of potassium disturbances in early risk stratification. The observed U-shaped association between potassium levels and mortality supports the potential value of potassium as a prognostic marker. However, whether correcting dyskalaemia improves outcomes remains to be determined.