Hyponatremia, Hypernatremia and Mortality in Patients with Chronic Kidney Disease with and without Congestive Heart Failure
Background—Hyponatremia is common in patients with conditions such as congestive heart failure, and is associated with increased mortality in hospitalized patients. Congestive heart failure is common in patients with chronic kidney disease (CKD), but the association of serum sodium concentration with mortality in such patients is not well characterized.
Methods and Results—We examined the association of serum sodium concentration (SeNa) with all-cause mortality in a nationally representative cohort of 655,493 US veterans with non-dialysis dependent CKD (95,961 (15%) of them with congestive heart failure). Associations were examined in time-dependent Cox models with adjustment for potential confounders. During a median follow-up of 5.5 years a total of 193,956 patients died (mortality rate, 95% confidence interval [CI]: 62.5/1000 patient-years, 62.2-62.8). The association of serum sodium level with mortality was U-shaped, with the lowest mortality seen in patients with sodium level of 140 mEq/l, and with both lower and higher levels showing significant associations with increased mortality. Patients with serum sodium levels of <130, 130-135.9, 145.1-150 and ≥150 compared to 136-145 mEq/l had multivariable adjusted mortality hazard ratios (95%CI) of 1.93 (1.83-2.03), 1.28 (1.26-1.30), 1.33 (1.28-1.38) and 1.56 (1.33-1.83), p<0.001 for all. The associations remained consistent in subgroups of patients with and without congestive heart failure.
Conclusions—Both lower and higher serum sodium levels are independently associated with higher mortality in patients with non-dialysis dependent CKD, irrespective of the presence of absence of congestive heart failure.
- Received August 30, 2011.
- Accepted December 30, 2011.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited