Sodium levels on admission are associated with mortality risk in hospitalized patients

Mortality and causes of death in patients hospitalized with hyponatremia - a propensity matched cohort study

BACKGROUND

Chronic hyponatremia is common in hospitalized patients and associated with high mortality. To what extent this reflects a causal effect remains uncertain.

METHODS

This study was based on the Stockholm Sodium Cohort, a longitudinal laboratory data repository covering 1.6 million individuals from 2005 to 2018. Using 1:1 propensity score matching, we explored mortality rates and causes of death in patients with mild (130-134 mmol/L), moderate (125-129 mmol/L), profound (120-124 mmol/L) or very profound (<120 mmol/L) hyponatremia compared to patients with normal (135-145 mmol/L) sodium concentrations on admittance to medical wards.

RESULTS

In total, 283 837 individuals fulfilled inclusion criteria, 79 407 of which had hyponatremia. Of these, 66 941 (52.7 % women) were successfully matched to counterparts with normal sodium concentrations. Thirty-day mortality rates were higher in patients with hyponatremia (HRs from 1.35 [95 % CI 1.28-1.42] in mild to 3.38 [95 % CI 2.16-5.28] in very profound hyponatremia). One-year mortality rates were marginally elevated in patients with mild hyponatremia (HR 1.04 [95 %CI 1.01-1.07]), but higher with more pronounced hyponatremia (HRs 1.18 [95 %CI 1.09-1.27] to 1.38 [95 %CI 1.11-1.69]). Excess 30-day mortality in mild, moderate, and profound hyponatremia was largely driven by malignant and gastrointestinal diseases.

CONCLUSIONS

Excess mortality with hyponatremia is proportional to the sodium disturbance but attenuates over time. However, causes of death suggest that residual confounding from imbalanced severity of underlying diseases is the main cause of increased mortality.

Decision tree model development and in silico validation for avoidable hospital readmissions at 30 days in a pediatric population

Introduction

Background and objective: identifying patients at high risk of avoidable readmission remains a challenge for healthcare professionals. Despite the recent interest in Machine Learning in this topic, studies are scarce and commonly using only black box algorithms. The aim of our study was to develop and validate in silico an interpretable predictive model using a decision tree inference to identify pediatric patients at risk of 30-day potentially avoidable readmissions. Methods: a retrospective cohort study was conducted with all patients under 18 years admitted to a tertiary university hospital. Demographic, clinical and nutritional data were collected from electronic databases. The outcome was the potentially avoidable 30-day readmissions. The J48 algorithm was used to develop the best-fit trees capable of classifying the outcome efficiently. Leave-one-out cross-validation was applied and we computed the area under the receiver operating curve (AUC). Results: the most important attributes of the model were C-reactive protein, hemoglobin and sodium levels, besides nutritional monitoring. We obtained an AUC of 0.65 and accuracy of 63.3 % for the full training and leave-one-out cross-validation. Conclusion: our model allows the identification of 30-day potentially avoidable readmissions through practical indicators facilitating timely interventions by the medical team, and might contribute to reduce this outcome.

Sodium fluctuation as a parameter in predicting mortality in general hospitalized patients

Background

Dysnatremia is the most common electrolyte disorder in hospitalized patients. Sodium fluctuation level may be a better parameter in dysnatremia management. We aimed to examine the association between sodium fluctuation level during hospitalization and mortality and to evaluate its value in predicting poor prognosis among general hospitalized patients.

Methods

Data were collected from patients admitted to Peking Union Medical College Hospital. The generalized estimated equation (GEE) was used to examine the relationship between sodium fluctuation level and mortality. Receiver-operating characteristic (ROC) curve analysis was performed to calculate the optimal cutoff value and the area under the ROC curve (AUC).

Results

Sodium fluctuation level showed a dose-dependent association with increased mortality in general hospitalized patients. After adjusting age, sex, length of hospital stay, and Charlson comorbidity index, the ORs of group G2 to G6 were 5.92 (95% CI 5.16-6.79), 26.45 (95% CI 22.68-30.86), 50.71 (95% CI 41.78-61.55), 104.38 (95% CI 81.57-133.58), and 157.64 (95% CI 112.83-220.24), respectively, p trend <0.001. Both normonatremia and dysnatremia patients on admission had the dose-dependent associations similar to general hospitalized patients. The AUC of sodium fluctuation level was 0.868 (95% CI 0.859-0.877) in general hospitalized patients, with an optimal cutoff point of 7.5 mmol/L, a sensitivity of 76.5% and a specificity of 84.2%.

Conclusion

We determined that sodium fluctuation level had a dose-dependent association with increased mortality in general hospitalized patients. Sodium fluctuation level could be used to develop a single parameter system in predicting mortality in general hospitalized patients with acceptable accuracy, sensitivity, and specificity.

Relationship of severity of hyponatremia and adverse outcomes in children visiting the emergency department

Mild hyponatremia is often found in patients visiting pediatric emergency departments (PEDs), but there are few large-scale studies on its association with adverse outcomes, including mortality. We conducted this study to identify the association of mild hyponatremia with adverse outcome. This retrospective observational study included children under 18 years of age visiting the PED at a tertiary hospital. We used electronic medical record data from January 1, 2009 to December 31, 2020. Clinical outcomes, including ward admission, vasopressor administration, pediatric intensive care unit (PICU) admission, and mortality, were assessed for the total of 44,147 patients. Among these, 1,639 (3.7%) were in the hyponatremia group, with 1,521 (3.4%) exhibiting mild hyponatremia. Mild hyponatremia was more prevalent in younger patients, particularly in the 1-3 years age group, and less common in females. Patients with mild hyponatremia had a significantly prolonged median length of stay in the PED compared to normonatremic patients (5.8 h vs. 4.4 h, p < 0.001). Moreover, they showed significantly higher rates of ward admission (51.1% vs. 35.6%, p < 0.001), vasopressor administration (1.1% vs. 0.6%, p = 0.014), PICU admission (2.4% vs. 1.0%, p < 0.001), and mortality (1.5% vs. 0.3%, p < 0.001). Compared with the normonatremia group, the odds ratios (95% CI) for ward admission, vasopressor administration, PICU admission, and mortality in the mild hyponatremia group were 1.90 (1.71-2.10), 1.91 (1.17-3.13), 2.62 (1.86-3.68), and 5.56 (3.51-8.80), respectively. Furthermore, our findings demonstrate a notable upward trend in adverse outcomes, including vasopressor administration, PICU admission, and mortality, from mild hyponatremia to severe hyponatremia. In conclusion, we found that adverse outcomes increase with the severity of hyponatremia in children presenting to the PED, highlighting the importance of immediate intervention alongside the identification of the underlying cause.

Impact of hyponatremia in patients hospitalized in Internal Medicine units: Hyponatremia in Internal Medicine units

The aim of this study was to analyze the impact and the clinical and evolutionary characteristics of hypotonic hyponatremia in patients hospitalized in Internal Medicine units. Prospective multicenter observational study of patients with hypotonic hyponatremia (<135 mmol/L) in 5 hospitals in southern Spain. Patients were included according to point prevalence studies carried out every 2 weeks between March 2015 and October 2017, by assessing demographic, clinical, analytical, and management data; each patient was subsequently followed up for 12 months, during which time mortality and readmissions were assessed. A total of 501 patients were included (51.9% women, mean age = 71.3 ± 14.24 years), resulting in an overall prevalence of hyponatremia of 8.3%. The mean comorbidities rate was 4.50 ± 2.41, the most frequent diagnoses being heart failure (115) (23%), respiratory infections (65) (13%), and oncological pathologies (42) (6.4%). Of the total number of hyponatremia cases, 180 (35.9%) were hypervolemic, 164 (32.7%) hypovolemic, and 157 (31.3%) were euvolemic. A total of 87.4% did not receive additional diagnostic tests to establish the origin of the condition and 30% did not receive any treatment. Hospital mortality was 15.6% and the mean length of stay was 14.7 days. Euvolemic and admission hyponatremia versus hyponatremia developed during admission were significantly associated with lower mortality rates (P = .037). Mortality at 1 year and readmissions were high (31% and 53% of patients, respectively). Hyponatremia was common in Internal Medicine areas, with hypervolemic hyponatremia being the most frequent type. The mortality rate was high during admission and at follow-up; yet there is a margin for improvement in the clinical management of this condition.

CARDS, a Novel Prognostic Index for Risk Stratification and In-Hospital Monitoring

Background: Sodium fluctuation is independently associated with clinical deterioration. We developed and validated a prognostic index based on sodium fluctuation for risk stratification and in-hospital monitoring. Methods: This study included 33,323 adult patients hospitalized at a tertiary care hospital in 2014. The first 28,279 hospitalizations were analyzed to develop the model and then the validity of the model was tested using data from 5044 subsequent hospitalizations. We predict in-hospital mortality using age, comorbidity, range of sodium fluctuation, and duration of sodium fluctuation, abbreviated as CARDS. Results: In-hospital mortality was similar in the derivation (0.6%) and validation (0.4%) cohorts. In the derivation cohort, four independent risk factors for mortality were identified using logistic regression: age (66-75, 2 points; >75, 3 points); Charlson comorbidity index (>2, 5 points); range of sodium fluctuation (7-10, 4 points; >10, 10 points); and duration of fluctuation (≤3, 3 points). The AUC was 0.907 (95% CI: 0.885-0.928) in the derivation cohort and 0.932 (95% CI: 0.895-0.970) in the validation cohort. In the derivation cohort, in-hospital mortality was 0.106% in the low-risk group (0-7 points), 1.076% in the intermediate-risk group (8-14 points), and 8.463% in the high-risk group (15-21 points). In the validation cohort, in-hospital mortality was 0.049% in the low-risk group, 1.064% in the intermediate-risk group, and 8.403% in the high-risk group. Conclusions: These results suggest that patients at low, intermediate, and high risk for in-hospital mortality may be identified by CARDS mainly based on sodium fluctuation.

Risk stratification and predictive value of serum sodium fluctuation for adverse prognosis in acute coronary syndrome patients

BACKGROUND

Serum sodium fluctuation (SF) as an indicator of the extent of changes in serum sodium is associated with increased mortality in hospitalized patients. However, there is no consensus on diagnostic criteria for SF, and its impact on the outcome of patients with acute coronary syndrome (ACS) remains uncertain. We defined SF and assessed its association with adverse prognosis in hospitalized ACS patients.

METHODS

Patients diagnosed with ACS were consecutively recruited. The serum SF rate (SFR) was defined as the ratio of the difference between the highest and lowest serum sodium levels during hospitalization to the initial serum sodium level on admission. The Cox proportional hazards model was performed to evaluate the association between SFR and mortality. The dose-response relationships of SFR with mortality was characterized by restricted cubic splines (RCS) model. The predictive performance of SF for mortality was assessed by the area under the receiver operating characteristic curves (AUCs).

RESULTS

The study retrospectively enrolled 1856 ACS patients, of which 36 (1.94%) patients dead within 1 year. Multivariate Cox analysis showed that SFR was independently associated with higher risk of 1-year mortality (HR = 1.17, 95% CI: 1.111-1.244, P < 0.001). RCS analysis showed the optimal threshold for SFR was 5%, and the 1-year cumulative mortality was higher in the abnormal SF group (SFR ≥ 5%) compared with the normal SF group (SFR < 5%, P < 0.01). The AUCs of SF for predicting mortality within 1 month, 6 months, and 1 year were 0.842 (95% CI: 0.781-0.904), 0.830 (95% CI:0.736-0.926), 0.703 (95% CI:0.595--0.811), respectively. Even in patients with normal baseline serum sodium, abnormal SF group demonstrated a significantly higher 1-year mortality compared to normal SF group (HR = 4.955, 95% CI: 1.919-12.795).

CONCLUSION

The SFR during hospitalization is an adequate predictor of adverse outcomes in ACS patients, independent of serum sodium level at admission. Additional research is warranted to ascertain whether interventions targeting SF confer measurable clinical benefits.

Validation of the HOSPITAL score as predictor of 30-day potentially avoidable readmissions in pediatric hospitalized population: retrospective cohort study

Potentially avoidable pediatric readmissions are a burden to patients and their families. Identifying patients with higher risk of readmission could help minimize hospital costs and facilitate the targeting of care interventions. HOSPITAL score is a tool developed and widely used to predict adult patient's readmissions; however its predictive capacity for pediatric readmissions has not yet been evaluated. The aim of the study was to validate the HOSPITAL score application to predict 30-day potentially avoidable readmissions in a pediatric hospitalized population. This is a retrospective cohort study with patients under 18 years old admitted to a tertiary university hospital (n = 6,344). The HOSPITAL score was estimated for each admission. Subsequently, we classified the patients as low (0-4), intermediate (5-6), and high (7-12) risk groups. In order to estimate the discrimination power, the sensitivity, specificity, and accuracy were determined by the receiver operating characteristics (ROC) and the calibration by the Hosmer-Lemeshow goodness-of-fit. The 30-day hospital readmission was 11.70% (745). The accuracy was 0.80 (CI 95%, 0.77, 0.83), with a sensitivity of 70.96% and specificity of 78.29%, and a good calibration (p = 0.34).    Conclusion: HOSPITAL score showed a good discrimination and can be used to predict 30-day potentially avoidable readmission in a large pediatric population with different medical diagnoses. Our study validates and expands the usefulness of the HOSPITAL score as a tool to predict avoidable hospital readmissions for pediatric population. What is Known: •   Pediatric readmissions burden patients, the family network, and the health system. In addition, it influences negatively child development. •   The HOSPITAL score is one of the tools developed and widely used to identify patients at high risk of hospital readmission, but its predictive capacity for pediatric readmissions has not been yet assessed. What is New: • The HOSPITAL score showed good ability to identify a risk of 30-day potentially avoidable readmission in a pediatric population in different clinical contexts and diagnoses. • Our study expands the usefulness of the HOSPITAL score as a tool for predicting hospital readmissions for children and adolescents.

Association of preoperative hyponatremia with surgical outcomes: a systematic review and meta-analysis of 32 observational studies

BACKGROUND

Preoperative hyponatremia is prevalent in patients undergoing surgical procedures, but it is uncertain if hyponatremia will lead to increased risk of surgical mortality and morbidity.

METHODS

A systematic search of Medline (PubMed), Embase and Cochrane Library from inception till 2 July 2021 was performed. Full length articles that reported on the association between surgical outcomes among adults ≥18 years with documented preoperative hyponatremia were included.

FINDINGS

We identified 32 observational studies comprising 1,301,346 participants. All studies had low risk of bias. When adjusted for covariates, patients with hyponatremia had significantly higher odds of developing major complications (defined as a composite measure of 9 major complications) compared to patients with normal sodium concentrations (aOR =  1.37, 95%CI = 1.23-1.53, I2 = 78%. N = 10). Additionally, patients with preoperative hyponatremia also significantly higher hazards of early mortality (<90 days) compared to patients with normonatremia (aHR = 1.27, 95%CI = 1.13-1.43, I2 = 97%. N = 10) after adjustment for covariates. Preoperative hyponatremia also had significant associations with respiratory, renal and septic complications. In terms of prognostic performance, preoperative hyponatremia performed adequately in predicting major complications in surgical patients (AUC = 0.70, LR- 0.90) with a specificity of 88% and a sensitivity of 25%.

INTERPRETATION

Our meta-analysis suggests that preoperative hyponatremia is associated with poorer early mortality and major morbidity outcomes in surgical patients. Hyponatremia is also a specific prognosticator for major complications in surgical patients, reiterating its potential use as a clinical indicator of poor outcomes.

Dysnatremia is associated with increased risk of all-cause mortality within 365 days post-discharge in patients with atrial fibrillation without heart failure: A prospective cohort study

AIM

The aim of this study is to evaluate the association between serum sodium concentrations at hospital admission and all-cause mortality within 365 days post-discharge in patients with atrial fibrillation (AF) without heart failure (HF).

METHODS

The prospective cohort study enrolled 1,446 patients with AF without HF between November 2018 and October 2020. A follow-up was performed 30, 90, 180, and 365 days after enrollment through outpatient visits or telephone interviews. All-cause mortality was estimated in three groups according to serum sodium concentrations: hyponatremia (< 135 mmol/L), normonatremia (135-145 mmol/L), and hypernatremia (> 145 mmol/L). We estimated the risk of all-cause mortalities using univariable and multivariable Cox proportional hazards models with normonatremia as the reference.

RESULTS

The all-cause mortalities of hyponatremia, normonatremia, and hypernatremia were 20.6, 9.4, and 33.3% within 365 days post-discharge, respectively. In the univariable analysis, hyponatremia (HR: 2.19, CI 1.5-3.2) and hypernatremia (HR: 4.03, CI 2.32-7.02) increased the risk of all-cause mortality. The HRs for hyponatremia and hypernatremia were 1.55 (CI 1.05-2.28) and 2.55 (CI 1.45-4.46) after adjustment for age, diabetes mellitus, loop diuretics, antisterone, antiplatelet drugs, and anticoagulants in the patients with AF without HF. The association between serum sodium concentrations and the HRs of all-cause mortality was U-shaped.

CONCLUSION

Dysnatremia at hospital admission was an independent factor for all-cause mortality in patients with AF without HF within 365 days post-discharge.

Association of Hypernatremia with Immune Profiles and Clinical Outcomes in Adult Intensive Care Unit Patients with Sepsis

Both hypernatremia and an abnormal immune response may increase hospital mortality in patients with sepsis. This study examined the association of hypernatremia with abnormal immune response and mortality in 520 adult patients with sepsis in an intensive care unit (ICU). We compared the mortality and ex vivo lipopolysaccharide (LPS)-induced inflammatory response differences among patients with hyponatremia, eunatremia, and hypernatremia, as well as between patients with acquired hypernatremia on ICU day 3 and those with sustained eunatremia over first three ICU days. Compared with eunatremia or hyponatremia, hypernatremia led to higher 7 day, 14 day, 28 day, and hospital mortality rates (p = 0.030, 0.009, 0.010, and 0.033, respectively). Compared with sustained eunatremia, acquired hypernatremia led to higher 7, 14, and 28 day mortality rates (p = 0.019, 0.042, and 0.028, respectively). The acquired hypernatremia group nonsignificantly trended toward increased hospital mortality (p = 0.056). Day 1 granulocyte colony-stimulating factor (G-CSF) and tumor necrosis factor (TNF) α levels were relatively low in patients with hypernatremia (p = 0.020 and 0.010, respectively) but relatively high in patients with acquired hypernatremia (p = 0.049 and 0.009, respectively). Thus, in ICU-admitted septic patients, hypernatremia on admission and in ICU-acquired hypernatremia were both associated with higher mortality. The higher mortality in patients with hypernatremia on admission was possibly related to the downregulation of G-CSF and TNF-α secretion after endotoxin stimulation. Compared to sustained eunatremia, acquired hypernatremia showed immunoparalysis at first and then hyperinflammation on day 3.

Hypernatremia in Hospitalized Patients: A Large Population-Based Study

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.

Dysnatremias in Chronic Kidney Disease: Pathophysiology, Manifestations, and Treatment

The decreased ability of the kidney to regulate water and monovalent cation excretion predisposes patients with chronic kidney disease (CKD) to dysnatremias. In this report, we describe the clinical associations and methods of management of dysnatremias in this patient population by reviewing publications on hyponatremia and hypernatremia in patients with CKD not on dialysis, and those on maintenance hemodialysis or peritoneal dialysis. The prevalence of both hyponatremia and hypernatremia has been reported to be higher in patients with CKD than in the general population. Certain features of the studies analyzed, such as variation in the cut-off values of serum sodium concentration ([Na]) that define hyponatremia or hypernatremia, create comparison difficulties. Dysnatremias in patients with CKD are associated with adverse clinical conditions and mortality. Currently, investigation and treatment of dysnatremias in patients with CKD should follow clinical judgment and the guidelines for the general population. Whether azotemia allows different rates of correction of [Na] in patients with hyponatremic CKD and the methodology and outcomes of treatment of dysnatremias by renal replacement methods require further investigation. In conclusion, dysnatremias occur frequently and are associated with various comorbidities and mortality in patients with CKD. Knowledge gaps in their treatment and prevention call for further studies.

Sodium alterations impair the prognosis of hospitalized patients with COVID-19 pneumonia

OBJECTIVE

Dysnatremia is common in hospitalized patients, often worsening the prognosis in pneumopathies and critical illnesses. Information on coronavirus disease-19 (COVID-19)-related hyponatremia is partially conflicting, whereas data on hypernatremia in this context are scarce. We assessed, in a cohort of COVID-19 inpatients: the prevalence of sodium alterations at admission and throughout their hospitalization; their association with inflammation/organ damage indexes; their short-term prognostic impact.

STUDY DESIGN AND METHODS

117 patients (81 males, 64 ± 13 years) hospitalized for COVID-19 between 1 March and 30 April 2020 were retrospectively followed-up for their first 21 days of stay by collecting all serum sodium measurements, basal CRP and serum lactate levels, maximum IL-6 and information on care setting, required ventilation, length of hospitalization, in-hospital death.

RESULTS

At admission, 26.5% patients had hyponatremia, and 6.8% had hypernatremia. During their hospitalization, 13.7% patients experienced both disorders ('mixed dysnatremia'). Lower sodium levels at admission were correlated with higher C reactive protein (CRP) (P = 0.039) and serum lactate levels (P = 0.019), but not interleukin-6 (IL-6). Hypernatremia and a wider sodium variability were associated with maximum required ventilation, need for ICU assistance and duration of the hospitalization. Mean estimated time to Intensive Care Unit (ICU) admission was 20 days shorter in patients exposed to sodium alterations at any time of their hospital course (log-rank test P = 0.032).

CONCLUSIONS

Sodium alterations frequently affect hospitalized COVID-19 patients. Hyponatremia could indicate pulmonary involvement, whereas hypernatremia is associated to prolonged hospitalization and the need for intensive care/mechanical ventilation, particularly when resulting from prior hyponatremia. Optimizing in-hospital sodium balance is crucial to improve patients' prognosis.

Preoperative hyponatremia predicts complications in older patients undergoing digestive tract surgery: a propensity score matching analysis

Aim

This study aimed to investigate the association between preoperative hyponatremia and life-threatening postoperative complications (including death) among older patients undergoing digestive tract surgery.

Findings

Preoperative hyponatremia was associated with an increased risk of life-threatening postoperative complications and mortality in older patients undergoing digestive tract surgery. Preoperative hyponatremia was also correlated with a higher risk of postoperative infectious complications.

Message

Preoperative hyponatremia can predict the development of life-threatening postoperative complications and mortality in older patients undergoing digestive tract surgery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-021-00559-4.

Purpose

Whether preoperative hyponatremia increases the risk of postoperative complications in older patients undergoing digestive tract surgery remains unclear. The purpose of the study was to investigate the association between preoperative hyponatremia and life-threatening postoperative complications (including death) among older patients undergoing digestive tract surgery.

Methods

This was a propensity score-matched, retrospective cohort study. We recruited older patients (≥ 65 years of age) who underwent digestive tract surgery in our institution. The propensity score matching (PSM; 1:2) was used to balance a range of covariates between patients with preoperative hyponatremia (serum sodium [Na⁺] levels < 135 mmol/L) and those with normal [Na⁺] levels (135–145 mmol/L). The primary outcome was the occurrence of life-threatening postoperative complications and mortality (i.e., Clavien–Dindo grade IV and V [CD IV and V] complications) during hospital stay. The relationship between preoperative hyponatremia and the development of CD IV and V complications was identified with logistic regression analysis.

Results

A total of 1076 patients were analyzed (mean age 73.9 years; 421 female [39.1%]). Preoperative hyponatremia was identified in 122 patients. After matching, 312 patients were included in the analyses (104 patients with preoperative hyponatremia and 208 patients with normal [Na⁺] levels; mean age, 76.3 years; 130 female [41.7%]). When compared with normal [Na⁺] levels, preoperative hyponatremia was associated with an increased risk of CD IV and V complications (odds ratio [OR] 2.082, 95% confidential interval [CI] 1.041–4.164, P = 0.038). Preoperative hyponatremia was also significantly associated with a higher risk of postoperative infectious complications (OR 2.158, 95% CI 1.138–4.091, P = 0.018).

Conclusion

Preoperative hyponatremia can predict an increased risk of life-threatening postoperative complications and mortality in older patients undergoing digestive tract surgery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41999-021-00559-4.

Increased Mortality in Elderly Patients Admitted with Hyponatremia: A Prospective Cohort Study

Hyponatremia is the most common electrolyte disorder, commonly affecting older hospitalized individuals; however, the literature is not clear regarding its effect on mortality. The aim of this 2-year observational prospective cohort study was to evaluate the mortality and re-admission rates, the clinical and laboratory characteristics and the causes of hyponatremia in patients older than 65 years admitted with a corrected serum sodium of 130 mEq/L or less in an internal medicine ward of a tertiary Greek university hospital. During the observation period, 138 patients (mean age 80.5 years, 36.2% male) fulfilled the inclusion criteria and were prospectively followed for 1 year after admission. Symptoms of hyponatremia were present in 59.4% of patients. Hypovolemia was the main sole cause of hyponatremia, but in about one third of patients, hyponatremia was multifactorial. Only a low proportion of patients (12.3%) fulfilled the criteria of the syndrome of inappropriate antidiuresis (SIAD) at admission according to the current guidelines. The re-admission rates at 3- and 12-months following discharge was 34.2% and 51.8%, respectively. Mortality during hospitalization was 17.4% and was higher compared to non-hyponatremic admitted older patients, while the total mortality at 1 year after admission was 28.3%, indicating that hyponatremia at admission is a marker of significant mortality during and after hospitalization in elderly patients.

The prognostic importance of serum sodium levels at hospital discharge and one-year mortality among hospitalized patients

BACKGROUND

The optimal range of serum sodium at hospital discharge is unclear. Our objective was to assess the one-year mortality based on discharge serum sodium in hospitalized patients.

METHODS

We analyzed a cohort of hospitalized adult patients between 2011 and 2013 who survived hospital admission at a tertiary referral hospital. We categorized discharge serum sodium into five groups; ≤132, 133-137, 138-142, 143-147, and ≥148 mEq/L. We assessed one-year mortality risk after hospital discharge based on discharge serum sodium, using discharge sodium of 138-142 mEq/L as the reference group.

RESULTS

Of 55 901 eligible patients, 4.9%, 29.8%, 56.1%, 8.9%, 0.3% had serum sodium of ≤132, 133-137, 138-142, 143-147, and ≥148 mEq/L, respectively. We observed a U-shaped association between discharge serum sodium and one-year mortality, with nadir mortality in discharge serum sodium of 138-142 mEq/L. When adjusting for potential confounders, including admission serum sodium, one-year mortality was significantly higher in both discharge serum sodium ≤137 and ≥143 mEq/L, compared with discharge serum sodium of 138-142 mEq/L. The mortality risk was the most prominent in elevated discharge serum sodium of ≥148 mEq/L (HR 3.86; 95% CI 3.05-4.88), exceeding the risk associated with low discharge serum sodium of ≤132 mEq/L (HR 1.43; 95% CI 1.30-1.57).

CONCLUSION

The optimal range of serum sodium at discharge was 138-142 mEq/L. Both hypernatremia and hyponatremia at discharge were associated with higher one-year mortality. The impact on higher one-year mortality was more prominent in hypernatremia than hyponatremia.

Sodium Abnormalities in Cardiac Surgery With Cardiopulmonary Bypass in Adults: A Narrative Review

Perioperative sodium abnormalities or dysnatremia is not uncommon in patients presenting for cardiac surgery and is associated with increased morbidity and mortality. Both the disease process of heart failure and its treatment may contribute to abnormalities in serum sodium concentration. Serum sodium is the main determinant of serum osmolality, which in turn affects cell volume. Brain cells are particularly vulnerable to changes in serum osmolality because of the nondistensible cranium. The potentially catastrophic neurologic sequelae of rapidly correcting chronic dysnatremia and the time-sensitive nature of cardiac surgery can make the management of these patients challenging. The use of cardiopulmonary bypass to facilitate surgery adds another layer of complexity in the intraoperative management of sodium and water balance. This narrative review examines the definition and classification of dysnatremia. It also covers the etiology and pathophysiology of dysnatremia, implications during cardiac surgery requiring cardiopulmonary bypass, and the perioperative management of dysnatremia.

Sodium levels during hospitalization with acute myocardial infarction are markers of in-hospital mortality: Soroka acute myocardial infarction II (SAMI-II) project

OBJECTIVE

Abnormalities in sodium homeostasis are common in hospitalized patients. Hyponatremia upon admission is a poor prognostic marker in acute myocardial infarction (AMI) patients. However, little is known about the association between changes in sodium levels and in-hospital mortality. We delineated changes in sodium levels and studied the association of such changes with in-hospital mortality of AMI patients.

METHODS

Retrospective analysis of AMI patients hospitalized for > 6 days. Sodium levels throughout the 6-day post-admission were divided into five equally sized groups (quintiles = Q) and thereafter categorized as follows: Q1 (< 135 mEq/L), Q2-Q4 (135-140 mEq/L, reference group), and Q5 (≥141 mEq/L).

PRIMARY OUTCOME

in-hospital mortality.

RESULTS

A total of 8306 patients (10,416 admissions) were included (mean age 67.8 ± 14.0 years, 33.4% women, 45.5% STEMI). In-hospital mortality was 6.6%. Q1 and Q5 upon admission were both related to higher risk for in-hospital mortality, compared with the reference group (OR 1.47 and OR 1.33, respectively, p < 0.001 each). Q1 was more frequent in non-survivors throughout the entire study period, while the prevalence of Q5 levels was similar in survivors and non-survivors upon admission carrying increasing mortality risk thereafter: for Q1 consistent OR 1.50, while for Q5 it, increased from OR 1.32 upon admission to OR 1.90 on the sixth day, p < 0.001.

CONCLUSIONS

Low and high sodium levels are associated with increased risk for in-hospital mortality in patients with AMI. The risk is unchanged for hyponatremia, while it consistently increases for increased sodium levels.