Association of Hyponatremia in Acute Stroke Stage with Three-Year Mortality in Patients with First-Ever Ischemic Stroke

Abstract

Background: Hyponatremia is the most common electrolyte disorder in hospitalized patients, and is frequently a marker of a significant underlying disease. The prognostic value of hyponatremia in patients with acute first-ever ischemic stroke is not known. We aimed to analyze whether hyponatremia in the acute stroke stage contributed to the risk of mortality or recurrent stroke in these patients. Methods: We studied 925 patients presenting with acute first-ever ischemic stroke between 2002 and 2004. Sodium levels were obtained on arrival at the emergency room within 3 days of acute stroke onset. Hyponatremia was defined as a serum sodium concentration of 134 mmol/l or less. Clinical presentation, stroke risk factors, associated medical disease, and outcome were recorded. All patients were followed for 3 years for survival analysis. A multivariate Cox proportional hazards model was used to identify risk factors for 3-year mortality in these patients. We also constructed Kaplan-Meier survival curves, and compared groups with hyponatremia and normonatremia by means of log rank tests for significant differences. Results: Among the patients with acute first-ever ischemic stroke, 107 (11.6%) were hyponatremic. Among stroke risk factors, the prevalence of diabetes mellitus was significantly higher among hyponatremic patients (p < 0.001). Prevalence of chronic renal insufficiency was also higher in the hyponatremic group (p = 0.002). Clinical presentations, such as the length of acute ward stay, initial impaired consciousness, and clinical course in acute stroke were similar among normo- and hyponatremic patients. Among the complications, pneumonia and urinary tract infection were significantly higher in hyponatremic than in normonatremic patients. After multivariate logistic regression analysis, diabetes mellitus and chronic renal insufficiency were associated with hyponatremia in these patients. Kaplan-Meier analysis indicated that the survival rate was significantly lower in hyponatremic patients than in normonatremic patients (log rank test; p value <0.001). After multivariate Cox proportional hazards model analysis, hyponatremia was a significant predictor of 3-year mortality in these patients after adjustment for related variables (p value = 0.003, hazard ratio = 2.23, 95% confidence interval: 1.30–3.82). Conclusion: Hyponatremia in the acute stroke stage is a predictor of 3-year mortality in patients with acute first-ever ischemic stroke that is independent of other clinical predictors of adverse outcome.

Hyponatremia at discharge as a predictor of 12-month clinical outcomes in hospital survivors after acute myocardial infarction

“…Hyponatremia, a common electrolyte disturbance, is associated with poor prognosis in patients with acute heart failure [1,2], liver cirrhosis [3], CKD [4,5], and stroke [17,18]. The prognostic value of serum sodium levels in patients with coronary artery disease has also been previously evaluated; however, the results obtained were conflicting [6][7][8][9][10][11].…”

Stroke-Associated Pneumonia: Major Advances and Obstacles

“…At the clinical level, a meta-analysis showed that fever is associated with morbidity and mortality after stroke [42]. Electrolyte imbalance, especially hyponatremia, may worsen cerebral edema [43] and hyponatremic stroke patients may have an increased long-term mortality [44]. The entry of bacteria and lipopolysaccharide into the blood stream activates the coagulation as well as fibrinolysis systems and may theoretically result in the extension of the infarcted area [45].…”

Prognostic Significance of Hyponatremia in Acute Intracerebral Hemorrhage: Pooled Analysis of the Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial Studies*

“…Hyponatremia is a consistent predictor of adverse outcomes not only in general medical and critically ill patients (11)(12)(13)(14) but also in those with acute ischemic stroke (15,16). A possible explanatory mechanism for the association in patients with stroke is fluid shift in intracranial tissue leading to cerebral edema, seizures, and delayed cerebral ischemia (17).…”