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Observational Study
. 2022 Apr 20;3(7):1144-1157.
doi: 10.34067/KID.0000702022. eCollection 2022 Jul 28.

Hypernatremia in Hospitalized Patients: A Large Population-Based Study

Soraya Arzhan  1 , Maria-Eleni Roumelioti  1 , Igor Litvinovich  1 , Cristian G Bologa  2 , Orrin B Myers  3 , Mark L Unruh  1   4
Affiliations
Observational Study

Hypernatremia in Hospitalized Patients: A Large Population-Based Study

Soraya Arzhan et al. Kidney360. .

Abstract

Background: Hypernatremia is a frequently encountered electrolyte disorder in hospitalized patients. Controversies still exist over the relationship between hypernatremia and its outcomes in hospitalized patients. This study examines the relationship of hypernatremia to outcomes among hospitalized patients and the extent to which this relationship varies by kidney function and age.

Methods: We conducted an observational study to investigate the association between hypernatremia, eGFR, and age at hospital admission and in-hospital mortality, and discharge dispositions. We analyzed the data of 1.9 million patients extracted from the Cerner Health Facts databases (2000-2018). Adjusted multinomial regression models were used to estimate the relationship of hypernatremia to outcomes of hospitalized patients.

Results: Of all hospitalized patients, 3% had serum sodium (Na) >145 mEq/L at hospital admission. Incidence of in-hospital mortality was 12% and 2% in hyper- and normonatremic patients, respectively. The risk of all outcomes increased significantly for Na >155 mEq/L compared with the reference interval of Na=135-145 mEq/L. Odds ratios (95% confidence intervals) for in-hospital mortality and discharge to a hospice or nursing facility were 34.41 (30.59-38.71), 21.14 (17.53-25.5), and 12.21 (10.95-13.61), respectively (all P<0.001). In adjusted models, we found that the association between Na and disposition was modified by eGFR (P<0.001) and by age (P<0.001). Sensitivity analyses were performed using the eGFR equation without race as a covariate, and the inferences did not substantially change. In all hypernatremic groups, patients aged 76-89 and ≥90 had higher odds of in-hospital mortality compared with younger patients (all P<0.001).

Conclusions: Hypernatremia was significantly associated with in-hospital mortality and discharge to a hospice or nursing facility. The risk of in-hospital mortality and other outcomes was highest among those with Na >155 mEq/L. This work demonstrates that hypernatremia is an important factor related to discharge disposition and supports the need to study whether protocolized treatment of hypernatremia improves outcomes.

Keywords: chronic kidney disease; hypernatremia; mortality; outcomes.

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Conflict of interest statement

M.L. Unruh reports consultancy for Cara Therapeutics to chair of Data Monitoring Committee; a consulting agreement between Cara and the University of New Mexico; research funding from Dialysis Clinic, Inc.; and honoraria from the American Society of Nephrology, NKF, and the Renal Research Institute related to lectures. M.-E. Roumelioti reports participating in Dialysis Clinic, Inc., quality meetings and receiving financial support. All remaining authors have nothing to disclose.

Figures

None
Graphical abstract
Figure 1.
Figure 1.
Flow chart of the sample selection process. aThe final cohort available for analysis. Serum sodium levels were corrected by adding 1.6 mEq/L for each 100 mg/dl above 100 mg/dl of the concomitantly measured serum glucose levels.
Figure 2.
Figure 2.
Restricted cubic splines of the crude probability of in-hospital mortality, discharge to a hospice, discharge to home, and discharge to a nursing facility as a function of serum sodium levels at hospital admission. These estimated probabilities were derived from a multinomial logistic regression model. Serum sodium levels were corrected by adding 1.6 mEq/L for each 100 mg/dl above 100 mg/dl of the concomitantly measured serum glucose levels.
Figure 3.
Figure 3.
Plot of odds ratios (95% CI) for in-hospital mortality and discharge to a hospice or nursing facility associated with different intervals of serum sodium levels (mEq/L) at hospital admission stratified by eGFR levels. The odds rations were derived from multinomial logistic regression models adjusted for age, sex, race, and the selected comorbidities and reasons for hospitalization. Discharge to home and serum sodium levels of 135–145 mEq/L served as the reference. Serum sodium levels were corrected by adding 1.6 mEq/L for each 100 mg/dl increase above 100 mg/dl of the concomitantly measured serum glucose levels. Error bars indicated 95% CI. 95% CI, 95% confidence interval.
Figure 4.
Figure 4.
Plot of relationships between serum sodium levels at hospital admission and length of hospitalization among those discharged to home stratified by eGFR/age.
Figure 5.
Figure 5.
Plot of the relative risk ratios (95% CI) for in-hospital mortality and discharge to a hospice or nursing facility associated with different intervals of serum sodium levels (mEq/L) at hospital admission stratified by eGFR levels with developing race/ethnicity in the model. (A) Before removing race from model. (B) After removing race from model. The sensitivity analyses were performed using the eGFR equation without a race covariate.
Figure 5.
Figure 5.
Plot of the relative risk ratios (95% CI) for in-hospital mortality and discharge to a hospice or nursing facility associated with different intervals of serum sodium levels (mEq/L) at hospital admission stratified by eGFR levels with developing race/ethnicity in the model. (A) Before removing race from model. (B) After removing race from model. The sensitivity analyses were performed using the eGFR equation without a race covariate.
Figure 6.
Figure 6.
Plot of the relative risk ratios (95% CI) for in-hospital mortality and discharge to a hospice or nursing facility associated with different intervals of serum sodium levels (mEq/L) at hospital admission stratified by age groups.
See this image and copyright information in PMC

Comment in

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