Prevalence and prognostic value of hyponatremia on admission in hospitalized patients with heart failure

Abstract

To investigate the prevalence and prognostic value of hyponatremia on admission in hospitalized patients for heart failure (HF) from the first HF management center in China. Consecutive adult (age of 18 years or older) symptomatic HF patients (NYHA functional class II-IV) admitted between March 2009 and March 2012 in our center were included in the present analysis. Hyponatremia was defined as a serum sodium level < 135 mmol/L. Association between hyponatremia on admission and in-hospital mortality as well as all-cause death and heart failure death during 1-year follow-up after discharge was analyzed. A total of 1 048 hospitalized patients for HF with complete baseline data were enrolled and the prevalence of hyponatremia on admission was 9.2% (96/1 048). Blood pressure was significantly lower while NYHA functional class and N-terminal pro-B type natriuretic peptide levels were significantly higher in hyponatremic patients than non-hyponatremic patients (all P < 0.05). Kaplan-Meier survival analysis showed that patients with hyponatremia on admission had significant higher in-hospital mortality (P < 0.01), all-cause death rate (P < 0.01) and HF death rate (P < 0.01) during 1-year follow-up post discharge compared with non-hyponatremic patients with. Multiple Cox proportional hazard analysis showed that hyponatremia on admission remained as independent predictor for all-cause death (hazard risk (HR) = 2.105, 95% confidence interval (CI) 1.460-3.036, P < 0.01) and HF death (HR = 2.458, 95% CI: 1.704-3.545, P < 0.01) after adjustment for other covariates. Hyponatremia is relatively common in patients hospitalized with HF in China and hyponatremia on admission is associated with higher in-hospital mortality and all-cause death and HF death one year after discharge.