Serum sodium and mortality in a national peritoneal dialysis cohort

Effect of long-term serum sodium levels on the prognosis of patients on maintenance hemodialysis

Abnormal serum Na (SNa) levels are common in patients with chronic kidney disease (CKD) which is associated with increased morbidity and mortality. There are relatively few studies on the effect of SNa indicators on the prognosis of patients undergoing maintenance hemodialysis (MHD). We aim to investigate the effect of long-term SNa levels on the survival and prognosis of patients undergoing hemodialysis (HD). Newly entered HD patients in the registration system of Zhejiang Provincial Dialysis Quality Control Center between January 1, 2010 and December 31, 2019 were included and followed up until December 31, 2020. Multiple sodium levels were collected from patients, defining long-term SNa as the mean of multiple SNa, according to which patients were grouped, with the prognostic differences between subgroups compared by Kaplan-Meier modeling and multifactorial Cox regression modeling. Finally, a total of 21,701 patients were included in this study and Cox regression showed that decreased SNa levels (Na < 135 mmol/L, HR = 1.704, 95% CI 1.408-2.063, p < 0.001; 135≦Na≦137.5 mmol/L, HR = 1.127,95% CI 1.016-1.250, p = 0.024) and elevated SNa levels (142.5 < Na≦145mmol/L, HR = 1.198, 95% CI 1.063-1.350, p = 0.003; Na > 145mmol/L, HR = 2.150, 95% CI 1.615-2.863, p < 0.001) were all independent risk factors for all-cause mortality in MHD patients.

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Association between systemic immune inflammation Index and all-cause mortality in incident peritoneal dialysis-treated CKD patients: a multi-center retrospective cohort study

BACKGROUND

Chronic inflammatory disorders in peritoneal dialysis (PD) contribute to the adverse clinical outcome. Systemic immune inflammation index (SII) is the novel and convenient measurement that is positively associated with various diseases. However, scarce is known regarding the association between SII with all-cause mortality among PD patients.

METHODS

In this multi-center retrospective cohort study, 1,677 incident patients with PD were enrolled. Eligible patients were stratified into groups based on SII level: tertile 1(< 456.76), tertile 2(456.76 to 819.03), and tertile 3(> 819.03). The primary endpoint was the all-cause mortality. Both Cox regression analysis and competing risk models were used to examine the association between SII and all-cause mortality. Subgroup analysis was performed to assess the influence of the SII tertiles on all-cause mortality in different subgroups.

RESULTS

During the follow-up period of 30.5 ± 20.0 months, 26.0% (437/1,677) patients died, of whom the SII tertile 3 group accounted for 39.1% (171/437) of the deaths. Patients in the SII tertile 3 group had a higher all-cause mortality rate than patients in the SII tertile 1 and 2 groups (log-rank = 13.037, P < 0.001). The SII tertile 3 group was significantly associated with 80% greater risk (95% confidence interval:1.13 to 2.85; P = 0.013) compared with the SII tertile 1 group in multivariable Cox regression analysis. The competing risk model also indicated that the relationship between SII tertiles and all-cause mortality remains (subdistribution hazard ratio: 1.86; 95% confidence interval: 1.15 to 2.02, P = 0.011). Furthermore, the relationship between the log-transformed SII and all-cause mortality in patients with PD was nearly linear (P = 0.124).

CONCLUSION

A close relationship was observed between the SII and all-cause mortality in patients undergoing PD, suggesting that more attention should be paid to the SII, which is a convenient and effective measurement in clinical practice.

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.

Serum Chloride and Mortality in patients on continuous ambulatory peritoneal dialysis: A multi-center retrospective study

BACKGROUND

Lower serum chloride is associated with a higher risk of mortality in the general population. However, the association has received little attention in peritoneal dialysis patients. The study aimed to examine the association between serum chloride and mortality in peritoneal dialysis patients.

METHODS

In this multicenter retrospective cohort study, 2376 Chinese incident patients on peritoneal dialysis between January 1, 2005, and March 31, 2020, were included. Patients were grouped according to quartiles of serum chloride at baseline. The associations of baseline serum chloride and cardiovascular mortality and all-cause mortality were evaluated using cause-specific hazards models.

FINDINGS

Of 2376 patients, the mean age was 45.9 (45.3,46.5) years, 50.1% of patients were men. The median serum chloride levels were 103.0 (99.0,106.9) mmol/L. During 9304.5 person-years of follow-up, 462 patients died, of which 235 deaths were caused by cardiovascular disease. The highest quartile group was associated with a higher risk of cardiovascular mortality (adjusted hazards ratio [HR], 2.95; 95% confidence interval [CI], 1.80 to 4.95) and all-cause mortality (adjusted HR, 2.03; 95% CI, 1.45 to 2.83) compared with the lowest quartile. The similar trend was also found when serum chloride levels were deal as continuous variable.

INTERPRETATION

Higher serum chloride at the initial of peritoneal dialysis was associated with a higher risk of cardiovascular mortality and all-cause mortality in patients on peritoneal dialysis.

FUNDING

This work was supported by Shanghai Municipal Health Commission (2019SY018).

Machine Learning Consensus Clustering of Hospitalized Patients with Admission Hyponatremia

Background: The objective of this study was to characterize patients with hyponatremia at hospital admission into clusters using an unsupervised machine learning approach, and to evaluate the short- and long-term mortality risk among these distinct clusters. Methods: We performed consensus cluster analysis based on demographic information, principal diagnoses, comorbidities, and laboratory data among 11,099 hospitalized adult hyponatremia patients with an admission serum sodium below 135 mEq/L. The standardized mean difference was utilized to identify each cluster’s key features. We assessed the association of each hyponatremia cluster with hospital and one-year mortality using logistic and Cox proportional hazard analysis, respectively. Results: There were three distinct clusters of hyponatremia patients: 2033 (18%) in cluster 1, 3064 (28%) in cluster 2, and 6002 (54%) in cluster 3. Among these three distinct clusters, clusters 3 patients were the youngest, had lowest comorbidity burden, and highest kidney function. Cluster 1 patients were more likely to be admitted for genitourinary disease, and have diabetes and end-stage kidney disease. Cluster 1 patients had the lowest kidney function, serum bicarbonate, and hemoglobin, but highest serum potassium and prevalence of acute kidney injury. In contrast, cluster 2 patients were the oldest and were more likely to be admitted for respiratory disease, have coronary artery disease, congestive heart failure, stroke, and chronic obstructive pulmonary disease. Cluster 2 patients had lowest serum sodium and serum chloride, but highest serum bicarbonate. Cluster 1 patients had the highest hospital mortality and one-year mortality, followed by cluster 2 and cluster 3, respectively. Conclusion: We identified three clinically distinct phenotypes with differing mortality risks in a heterogeneous cohort of hospitalized hyponatremic patients using an unsupervised machine learning approach.

A Systematic Review and Meta-Analysis: Hyponatremia Predicted All-Cause and Cardiovascular Mortality in Dialysis Population

BACKGROUND

Hyponatremia is one of the most common disorders of electrolytes. Some research studies reported that hyponatremia was closely associated with mortality in patients with dialysis. However, this viewpoint remains controversial.

OBJECTIVE

We aimed to do a systematic review and meta-analysis to assess the influence of hyponatremia on mortality in patients with dialysis.

METHODS

We identified the eligible studies that investigated the association between hyponatremia and mortality risk in patients under dialysis by searching systematically a series of databases including PubMed, Embase, Cochrane, Web of science, and Ovid from January 2011 to June 2020. Adjusted hazard ratios (HRs) with 95% confidence intervals (95% CIs) were pooled.

RESULTS

From 1,116 records identified, 12 studies including prospective and retrospective cohort studies met our inclusion criteria. We found hyponatremia both at baseline (HR: 1.50 and 95% CI: 1.41-1.59) and in time-varying (HR: 1.63 and 95% CI: 1.44-1.84) were significantly correlated to all-cause mortality after multivariable adjusted. By the subgroup analysis, the same results were presented in hemodialysis (HR: 1.48 and 95% CI: 1.38-1.59) or peritoneal dialysis patients (HR: 1.52 and 95% CI: 1.37-1.70). We also observed that lower serum sodium was independently associated with cardiovascular death.

CONCLUSIONS

Hyponatremia was independently associated with all-cause and cardiovascular mortality, and it might predict adverse outcomes of patients under dialysis.

Prediction of premature all-cause mortality in patients receiving peritoneal dialysis using modified artificial neural networks

Premature all-cause mortality is high in patients receiving peritoneal dialysis (PD). The accurate and early prediction of mortality is critical and difficult. Three prediction models, the logistic regression (LR) model, artificial neural network (ANN) classic model and a new structured ANN model (ANN mixed model), were constructed and evaluated using a receiver operating characteristic (ROC) curve analysis. The permutation feature importance was used to interpret the important features in the ANN models. Eight hundred fifty-nine patients were enrolled in the study. The LR model performed slightly better than the other two ANN models on the test dataset; however, in the total dataset, the ANN models fit much better. The ANN mixed model showed the best prediction performance, with area under the ROC curves (AUROCs) of 0.8 and 0.79 for the 6-month and 12-month datasets. Our study showed that age, diastolic blood pressure (DBP), and low-density lipoprotein cholesterol (LDL-c) levels were common risk factors for premature mortality in patients receiving PD. Our ANN mixed model had incomparable advantages in fitting the overall data characteristics, and age is a steady risk factor for premature mortality in patients undergoing PD. Otherwise, DBP and LDL-c levels should receive more attention for all-cause mortality during follow-up.

The Association Between Handgrip Strength and Predialysis Serum Sodium Level in Patients With Chronic Kidney Disease Stage 5D

Purpose: Handgrip strength (HGS) is a useful tool for the systematic assessment of muscle function related to nutritional status. Reduced HGS has been associated with adverse clinical outcomes in chronic kidney disease (CKD) stage 5D patients. In the same patients, predialysis low serum sodium (sNa) has been associated with malnutrition and mortality. Here, we investigated the role of predialysis sNa on muscle function in CKD-5D patients.

Methods: We evaluated 45 patients on hemodialysis (HD) and 28 patients on peritoneal dialysis (PD) with HGS measurement, bioimpedance analysis, anthropometric measures, and malnutrition inflammation score (MIS). According to established diagnostic criteria, reduced HGS was defined as strength below 30 and 20 Kg in men and women, respectively. Predialysis sNa values were defined as the mean of all predialysis measurements during the preceding 6 months. Data analysis was performed separately for each of the HD and PD groups.

Results: The proportions of reduced HGS did not differ between the HD (66%) and PD (54%) groups, respectively. Patients in the HD group as compared to those in the PD group had higher serum albumin and potassium and mid-arm muscle circumference and lower residual renal function (RRF) and residual urine volume. Multivariate logistic analysis, after controlling for muscle mass, nutritional biomarkers, MIS, fluid overload and RRF, showed that for every 1 mmol/l increase of sNa the odds of reduced HGS was decreased by 60% (OR = 0.40, 95% CI: 0.16–0.99) and 42% (OR = 0.58, 95% CI: 0.36–0.93) in HD and PD patients, respectively. However, stratified analysis indicated that lower sNa levels predicted reduced HGS in individuals with a background of malnutrition, inflammation, overhydration and less preserved RRF, representing unfavorable conditions strongly related to muscle wasting in the dialysis setting.

Conclusions: Predialysis sNa is a strong and independent determinant of HGS, a reliable nutritional marker in CKD-5D stage patients. However, according to our findings, lower sNa levels appear to be a marker of underlying unfavorable conditions that are heavily associated with reduced HGS, rather than a causal determinant of reduced HGS. Whether optimizing sNa levels improves patient muscle performance requires further investigations.

Serum Sodium Modifies the Association of Systolic Blood Pressure with Mortality in Peritoneal Dialysis Patients

INTRODUCTION

High serum sodium is associated with increased blood pressure (BP) in dialysis patients, which is a risk factor for cardiovascular (CV) disease. However, the interaction between serum sodium and BP and their association with clinical outcomes in peritoneal dialysis (PD) patients is uncertain.

METHODS

We analyzed a retrospective cohort of 1,656 incident PD patients from January 2006 to December 2013, who were followed up until December 2018. Cox proportional hazards regression models were used to evaluate the association of serum sodium and BP with all-cause and CV mortality. A priori interaction between serum sodium and systolic BP (SBP) was explored, and a subgroup analysis was performed by stratifying SBP into the following 3 groups: <110, 110-130, and >130 mm Hg.

RESULTS

Mean baseline serum sodium was 140.2 ± 3.6 mmol/L, mean SBP was 137 ± 20 mm Hg, and diastolic BP was 85 ± 14 mm Hg. During a median (range) follow-up time of 46.5 (2.6-154.3) months, 507 patients died, 252 of whom died due to CV disease. SBP did not predict all-cause and CV mortality when BP was assessed as a continuous variable. However, SBP >130 or <110 mm Hg was associated with higher risk of all-cause and CV mortality compared with SBP of 110-130 mm Hg. There was a significant interaction between baseline serum sodium and SBP for all-cause mortality (p for interaction = 0.016). In subgroup analysis, among those with SBP >130 mm Hg, the risk of all-cause mortality was elevated in those with serum sodium ≥140 mmol/L (adjusted hazard ratio [aHR] 1.45 [95% confidence interval (CI): 1.07-1.98]), but not for those with serum sodium <140 mmol/L (aHR 1.27 [95% CI: 0.89-1.82]). Conversely, among those with SBP <110 mm Hg, those with serum sodium <140 mmol/L had an elevated risk of mortality (aHR 1.99 [95% CI: 1.31-3.02]), but not those with serum sodium ≥140 mmol/L (aHR 1.15 [95% CI: 0.74-1.79]) (p for interaction = 0.028).

CONCLUSION

The association of BP with mortality was modified by serum sodium levels in PD patients. Further studies are needed to evaluate whether individualized BP control based on serum sodium levels contributes to improve patient outcomes.

Possible association between dysnatremias and mortality during hospitalization in patients undergoing acute hemodialysis: analysis from a Peruvian retrospective cohort

Objective:

To evaluate the association between dysnatremias or dyschloremias and mortality during hospitalization in patients with acute kidney injury (AKI) or chronic kidney disease (CKD) undergoing acute hemodialysis.

Methods:

We carried out a retrospective cohort study on adult patients undergoing acute hemodialysis with AKI or CKD diagnosis at a public hospital in Lima, Peru. Dysnatremias were categorized as hyponatremia (Na < 135mmol/L) or hypernatremia (Na > 145mmol/L), and dyschloremias were defined as hypochloremia (Cl < 98 mmol/L) or hyperchloremia (Cl > 109mmol/L). The outcome of interest was mortality during hospitalization. We performed generalized lineal Poisson family models with bias-corrected and accelerated non-parametric bootstrap to estimate the risk ratios at crude (RR) and adjusted analysis (aRR) by gender, age, HCO3 (for all patients) and Liaño score (only for AKI) with CI95%.

Results:

We included 263 patients (mean age: 54.3 years, females: 43%): 191 with CKD and 72 with AKI. Mortality was higher in patients with AKI (59.7%) than in patients with CKD (14.1%). In overall, patients with hypernatremia had a higher mortality during hospitalization compared to those who had normal sodium values (aRR: 1.82, 95% CI: 1.17-2.83); patients with hyponatremia did not have different mortality (aRR: 0.19, 95% CI: 0.69-2.04). We also found that hyperchloremia (aRR: 1.35, 95% CI: 0.83-2.18) or hypochloremia (aRR: 0.66, 95% CI: 0.30-14.78) did not increase mortality in comparison to normal chloride values. No association between dysnatremias or dyschloremias and mortality during hospitalization was found in CKD and AKI subgroups.

Conclusions:

In our exploratory analysis, only hypernatremia was associated with mortality during hospitalization among patients with AKI or CKD undergoing acute hemodialysis.

Hyponatremia in the Dialysis Population

Sodium derangements are among the most frequently encountered electrolyte disorders in patients with end-stage renal disease. As dialysis patients are predisposed to hyponatremia via multiple pathways, assessment of extracellular volume status is an essential first step in disentangling potential etiologic factors. In addition, multiple large population-based studies indicate that proxies of malnutrition (e.g., low body mass index, serum albumin, and serum creatinine levels) and loss of residual kidney function are important determinants of hyponatremia in dialysis patients. Among hemodialysis and peritoneal dialysis patients, evidence suggests that incrementally lower sodium levels are associated with increasingly higher death risk, highlighting the long-term risk of hyponatremia. Whereas in conventional survival models incrementally lower serum sodium concentrations are associated with worse mortality in hemodialysis patients, studies that have examined repeated measures of predialysis sodium have demonstrated mixed associations of time-varying sodium with higher mortality risk (i.e., U-shaped vs. inverse linear relationships). Although the causality of the hyponatremia-mortality association in dialysis patients remains uncertain, there are several plausible pathways by which lower sodium levels may lead to higher death risk, including central nervous system toxicity, falls and fractures, infection-related complications, and impaired cardiac function. Areas of uncertainty ripe for future studies include the following: (i) mechanistic pathways by which lower serum sodium levels are linked with higher mortality in dialysis patients, (ii) whether correction of sodium derangements improves outcomes, (iii) the optimal sodium target, and (iv) the impact of age and other sociodemographic factors on hyponatremia-outcome associations.

Association of serum sodium and risk of all-cause mortality in patients with chronic kidney disease: A meta-analysis and sysematic review

Studies on the association of dysnatraemia with all-cause mortality risk in chronic kidney disease (CKD) patients have yielded inconsistent results. This meta-analysis aimed to evaluate the association of hyponatremia or hypernatremia with all-cause mortality risk in CKD patients. An electronic literature search was performed in Web of Science, Pubmed and Embase databases from inception to March 2017 for available observational studies evaluating the association of dysnatraemia with all-cause mortality risk in CKD patients. Pooled hazard risk (HR) with 95% confidence interval (CI) was calculated for hyponatremia or hypernatremia vs. normonatremia. Seven studies that enrolled 742,979 CKD patients were identified. Baseline hyponatremia (HR 1.34; 95% CI: 1.15-1.57), and not hypernatremia (HR 1.12; 95%: CI 0.93-1.34), was independently associated with increased risk of all-cause mortality, when compared than the normonatremia category. In time-dependent analyses, both time-averaged hyponatremia (HR 1.65; 95% CI: 1.27-2.15) and hypernatremia (HR 1.41; 95% CI: 1.20-1.65) had a higher independent risk of all-cause mortality. Furthermore, subgroup analyses by type of patients, study design, sample size and follow-up duration revealed similar results across most of these analyses. Baseline hyponatremia and time-dependent hyponatremia or hypernatremia were independently associated with increased all-cause mortality risk in CKD patients.

Mortality rates are lower in SIAD, than in hypervolaemic or hypovolaemic hyponatraemia: Results of a prospective observational study

OBJECTIVE

Hyponatraemia is associated with increased mortality, but the mortality associated specifically with SIAD is not known. We hypothesized that mortality in SIAD was elevated, but that it was less than in hypervolaemic (HEN) or hypovolaemic (HON) hyponatraemia.

DESIGN

Mortality rates are presented as risk ratios (RR),with 95% confidence intervals (CI), and compared to normonatraemic controls (NN).

METHODS

Prospective, single centre, noninterventional study of all patients with hyponatraemia (≤130 mmol/L) admitted to hospital.

RESULTS

A total of 1323 admissions with hyponatraemia were prospectively evaluated and 1136 contemporaneous NN controls. 431(32.6%) hyponatraemic patients had HON, 573(43.3%) had SIAD and 275(20.8%) patients had HEN. In patient mortality was higher in hyponatraemia than NN (9.1% vs 3.3%, P<.0001). The RRs for in-hospital mortality compared to NN were: SIAD, 1.76 (95% CI 1.08-2.8, P=.02), HON 2.77 (95% CI 1.8-4.3, P<.0001) and HEN, 4.9 (95% CI 3.2-7.4, P<.0001). The mortality rate was higher in HEN (RR 2.85; 95% CI 1.86-4.37, P<.0001) and in HON, (RR 1.6; 95% CI 1.04-2.52; P=.03), when compared to SIAD. The Charlson Comorbidity Index was lower in SIAD than in eunatraemic patients (P<.0001). 9/121(7.4%) patients died with plasma sodium <125 mmol/L and 4(3.3%) with plasma sodium <120 mmol/L. However, 69/121(57%) patients died with a plasma sodium above 133 mmol/L.

CONCLUSIONS

We confirmed higher all-cause mortality in hyponatraemia than in NN. Mortality was higher in SIAD than in normonatraemia and was not explained on the basis of co-morbidities. Mortality was higher in HON and HEN than in SIAD. Mortality rates reported for all-cause hyponatraemia in the medical literature are not applicable to SIAD.

Electrolyte and Acid-Base Disorders in Chronic Kidney Disease and End-Stage Kidney Failure

The kidneys play a pivotal role in the regulation of electrolyte and acid-base balance. With progressive loss of kidney function, derangements in electrolytes and acid-base inevitably occur and contribute to poor patient outcomes. As chronic kidney disease (CKD) has become a worldwide epidemic, medical providers are increasingly confronted with such problems. Adequate diagnosis and treatment will minimize complications and can potentially be lifesaving. In this review, we discuss the current understanding of the disease process, clinical presentation, diagnosis and treatment strategies, integrating up-to-date knowledge in the field. Although electrolyte and acid-base derangements are significant causes of morbidity and mortality in CKD and end-stage renal disease patients, they can be effectively managed through a timely institution of combined preventive measures and pharmacological therapy. Exciting advances and several upcoming outcome trials will provide further information to guide treatment and improve patient outcomes.