Clinical outcomes in patients hospitalized with hyponatremia in the Northern territory of australia: A Retrospective, longitudinal Data-Linkage study.

PURPOSE: Hyponatremia is a common electrolyte disorder in hospitalized patients, associated with various adverse outcomes. This study aimed to evaluate the prevalence, associated clinical characteristics, and outcomes of hyponatremia among a large cohort of hospitalized Australian patients. METHODS: A retrospective cohort study involving 33,383 hospitalized patients with serum sodium concentrations categorized as normal (135–145 mmol/L), mild hyponatremia (130–134 mmol/L), moderate hyponatremia (125–129 mmol/L), and profound hyponatremia (< 125 mmol/L). The follow-up period extended up to 10 years. The Cox proportional hazards model was used to analyze time-to-death outcomes. RESULTS: The overall prevalence of hyponatremia was 25.5%, with mild, moderate, and profound cases accounting for 22.0%, 2.5%, and 1.0%, respectively. First Nations Australians had a higher incidence of hyponatremia compared to non-First Nation patients (33.6% vs. 21.8%, p < 0.001). Patients with all levels of hyponatremia were older and had lower albumin and eGFR levels. All levels of hyponatremia were associated with longer hospital stays (p < 0.001). Mortality rates were notably higher among patients with hyponatremia compared to normonatremia, with hazard ratios (HRs) of 1.73 (95%CI 1.57–1.91, p < 0.001), 2.24 (95%CI 1.91, 2.64, p < 0.001), and 1.99 (95%CI 1.58, 2.51, p < 0.001) for mild, moderate, and profound hyponatremia, respectively. CONCLUSIONS: Hyponatremia was highly prevalent in hospitalized patients and was associated with increased morbidity and mortality. Early recognition and targeted management strategies, especially in high-risk populations such as the elderly and First Nations Australians should be implemented.