Association of Admission Hyponatremia with In-Hospital Mortality in Patients with Acute Heart Failure: A Prospective Cohort Study

Abstract

Objectives: To determine the association between low admission serum sodium levels (hyponatremia) and in-hospital mortality among patients presenting with acute heart failure. Methodology: A total of 238 patients aged 20–60 years presenting with acute heart failure of less than seven days duration were enrolled using consecutive sampling. Patients were categorized into exposed (hyponatremia; serum sodium <135 mEq/L) and unexposed (normonatremia; 135–145 mEq/L) groups at admission. Patients with hypothyroidism, nephrotic syndrome, chronic liver disease, or chronic kidney disease were excluded. Serum sodium levels were measured at admission using standardized laboratory methods. Patients were followed throughout hospitalization to assess outcomes, including mortality and length of hospital stay. Relative risk (RR) with 95% confidence interval (CI) was calculated, and statistical significance was set at p≤0.05. Results: In-hospital mortality was significantly higher in patients with hyponatremia compared to normonatremic patients (26.9% vs 8.4%; RR 3.20, 95% CI 1.65–6.21; p=0.0006). The mean duration of hospital stay was also longer in the hyponatremia group (4.01 ± 2.40 days vs 2.40 ± 2.61 days). Conclusion: Hyponatremia at admission is significantly associated with increased in-hospital mortality and prolonged hospitalization among patients with acute heart failure. Early identification of hyponatremia may aid in risk stratification and clinical decision-making.