Association between salt intake and long-term mortality in hemodialysis patients: A retrospective cohort study

Interdialytic weight gain and low-salt diet in patients on chronic hemodialysis: A systematic review and meta-analysis

OBJECTIVE

The present systematic review and meta-analysis aims to determine the difference in the interdialytic weight gain (IDWG) between low salt intake diet and normal/high salt intake diet or between nutritional counseling aimed at reducing diet salt intake and no nutritional counseling in patients on chronic hemodialysis.

METHODS

Medline, PubMed, Web of Science, and the Cochrane Library were searched. Randomized, crossover or parallel studies and observational studies were considered for inclusion and: 1) included adult patients on chronic hemodialysis since at least 6 months; 2) compared normal salt intake diet with low salt intake diet on IDWG; 3) compared nutritional counseling aimed at reducing diet salt intake with no intervention on IDWG; 4) reported on IDWG.

RESULTS

Eight articles (783 patients) were fully assessed for eligibility and included in the investigation. Meta-analysis showed frequencies of patients that increased their weight after dialysis more than 2.5 Kg (events) over total enrolled subjects for each group (control and experimental). As no significant heterogeneity was observed (I2 = 8%; p = 0.36), the pooled analysis was performed using a fixed-effect model. Funnel plot was generated and no obvious asymmetry was observed. The Overall Odds Ratio to get an event in the experimental group, in respect to controls, is 0.57 (0.33-0.97) (p = 0.04] with single studies OR ranging between 0.11 and 1.08.

CONCLUSION

The present systematic review and meta-analysis suggest that the use of a low salt diet sodium or a nutritional counseling aimed at reducing diet salt intake is associated with a statistically significant reduction of the IDWG in patients on chronic hemodialysis.

Association between home meal preparers and salt intake in haemodialysis patients: a cross-sectional study

OBJECTIVES

This study aimed to examine the association between home meal preparer and salt intake among haemodialysis patients, including daily dietary status. We hypothesised that salt intake is higher among individuals who rely on meal preparation from others than those who prepare meals by themselves.

DESIGN

Cross-sectional study.

SETTING

Two medical facilities in Fukushima Prefecture, Japan.

PARTICIPANTS

237 haemodialysis outpatients who visited one of the medical facilities between February 2020 and August 2021 and were diagnosed with anuria, defined as urination of <100 mL/day, were the potential participants of the present study. Finally, 181 participants (131 male and 50 female) were included in the analysis.

OUTCOME MEASURE

Salt intake amount was calculated from the results of predialysis and postdialysis blood draws, using Watson's formula based on predialysis weight, predialysis serum sodium level, postdialysis weight and serum sodium level at the end of dialysis.

RESULTS

Salt intake was significantly higher in participants who relied on meal preparation from others ('relying on others') than those who prepared meals by themselves ('self-prepared') (B=1.359; 95% CI: 0.495 to 2.222). No statistical difference was found between individuals who ate out or ate takeout ('outsourcing') and those who prepared their own meals ('self-prepared'). These results were robust after adjustment for confounding factors.

CONCLUSIONS

The present study revealed an association between self-preparation of meals at home and reduced salt intake among dialysis patients. Our findings suggest that whoever is the home meal preparer is possibly a social determinant of salt intake. To improve the prognosis of haemodialysis patients, actively reaching out to the family and assessing their social environment, such as identifying the home meal preparer and, if the patient relies on others for meal preparation, conducting nutritional/dietary guidance for that person, are effective in enhancing salt reduction.

Serum chloride as a marker of cardiovascular and all-cause mortality in chronic hemodialysis patients: 5-Year follow-up study

BACKGROUND

Hypochloremia has been associated with increased mortality in patients with hypertension, heart failure, sepsis, and chronic kidney disease (CKD). The pathophysiological mechanisms of this finding are not clear. There are no studies describing an association between serum chloride levels (Cl-) and mortality in incident chronic hemodialysis (HD) patients.

METHOD

Retrospective cohort study of the incident population in our chronic outpatient hemodialysis program between January 1, 2016, and January 1, 2021 (N=374). Survival time was collected in all patients and analyzed using the Kaplan-Meyer method. A multivariate Cox regression model was performed to predict the probability of survival, applying a stepwise procedure.

RESULTS

During the median follow-up period of 20 months, 83 patients died. The 5-year overall survival rate for our patients was 45%. Both natremia and chloremia had no significant differences when compared by sex, vascular access, or etiology. There was an inverse correlation between Cl- and interdialytic weight gain (r=-0.15) (p=0.0038). Patients belonging to the quartile with lower Cl- levels had less probability of survival than patients in the quartile with higher Cl- levels (27% and 68%, respectively, p=0.019). On the other hand, in the multivariate Cox regression model, variables significantly associated with higher mortality were being older, having higher baseline comorbidity by modified Charlson index, not taking diuretics and having lower albumin and chloride levels. Particularly, higher Cl- levels was independently associated with both lower all-cause mortality (adjusted hazard ratio [HR]=0.84; 95% confidence interval [CI], 0.77-0.92; p=0.0001) and cardiovascular mortality (HR 0.9; 95% CI, 0.83-0.97; p<0.0057).

CONCLUSIONS

Lower Cl- levels were associated with higher all-cause and cardiovascular mortality in incident patients on chronic hemodialysis in our health area.

Protect the Kidneys and Save the Heart Using the Concept of Food as Medicine

Chronic kidney disease is a significant risk factor for cardiovascular disease. In addition to traditional risk factors, such as hypertension, dyslipidemia, diabetes and smoking, patients with chronic kidney disease have a uremic phenotype marked by premature aging, mitochondrial dysfunction, persistent low-grade inflammation, gut dysbiosis and oxidative stress. These complications contribute to abnormal vascular and myocardial remodeling processes, resulting in accelerated vascular calcification, cellular and organ senescence and a high risk of cardiovascular disease. Nonpharmacological strategies, such as increasing physical activity and a healthy diet, may slow the progression of kidney disease and consequently protect the heart. Thus, a deep promotion and advocacy of nutritional guidance based on scientific data is needed. This narrative review discusses how nutritional interventions may delay progressive organ damage in the kidney-heart axis.

Results of Salt Intake Restriction Monitored with the New Sodium Control Biosensor

INTRODUCTION

Adherence to a low-sodium (Na) diet is crucial in patients under hemodialysis, as it improves cardiovascular outcomes and reduces thirst and interdialytic weight gain. Recommended salt intake is lower than 5 g/day. The new 6008 CAREsystem monitors incorporate a Na module that offers the advantage of estimating patients' salt intake. The objective of this study was to evaluate the effect of dietary Na restriction for 1 week, monitored with the Na biosensor.

METHODS

A prospective study was conducted in 48 patients who maintained their usual dialysis parameters and were dialyzed with a 6008 CAREsystem monitor with activation of the Na module. Total Na balance, pre-/post-dialysis weight, serum Na (sNa), changes in pre- to post-dialysis sNa (ΔsNa), diffusive balance, and systolic and diastolic blood pressure were compared twice, once after 1 week of patients' usual Na diet and again after another week with more restricted Na intake.

RESULTS

Restricted Na intake increased the percentage of patients on a low-Na diet (<85 Na mmol/day) from 8% to 44%. Average daily Na intake decreased from 149 ± 54 to 95 ± 49 mmol, and interdialytic weight gain was reduced by 460 ± 484 g per session. More restricted Na intake also decreased pre-dialysis sNa and increased both intradialytic diffusive balance and ΔsNa. In hypertensive patients, reducing daily Na by more than 3 g Na/day lowered their systolic blood pressure.

CONCLUSIONS

The new Na module allowed objective monitoring of Na intake, which in turn could permit more precise personalized dietary recommendations in patients under hemodialysis.

Tissue Sodium Accumulation Induces Organ Inflammation and Injury in Chronic Kidney Disease

High salt intake is a primary cause of over-hydration in chronic kidney disease (CKD) patients. Inflammatory markers are predictors of CKD mortality; however, the pathogenesis of inflammation remains unclear. Sodium storage in tissues has recently emerged as an issue of concern. The binding of sodium to tissue glycosaminoglycans and its subsequent release regulates local tonicity. Many cell types express tonicity-responsive enhancer-binding protein (TonEBP), which is activated in a tonicity-dependent or tonicity-independent manner. Macrophage infiltration was observed in the heart, peritoneal wall, and para-aortic tissues in salt-loading subtotal nephrectomized mice, whereas macrophages were not prominent in tap water-loaded subtotal nephrectomized mice. TonEBP was increased in the heart and peritoneal wall, leading to the upregulation of inflammatory mediators associated with cardiac fibrosis and peritoneal membrane dysfunction, respectively. Reducing salt loading by a diuretic treatment or changing to tap water attenuated macrophage infiltration, TonEBP expression, and inflammatory marker expression. The role of TonEBP may be crucial during the cardiac fibrosis and peritoneal deterioration processes induced by sodium overload. Anti-interleukin-6 therapy improved cardiac inflammation and fibrosis and peritoneal membrane dysfunction. Further studies are necessary to establish a strategy to regulate organ dysfunction induced by TonEBP activation in CKD patients.

Nutritional and Hydration Status and Adherence to Dietary Recommendations in Dalmatian Dialysis Patients

Protein-energy wasting (PEW) is considered one of the major complications of chronic kidney disease (CKD), particularly in dialysis patients. Insufficient energy and protein intake, together with clinical complications, may contribute to the onset and severity of PEW. Therefore, the aim of the study was to analyze the differences in nutritional and hydration status and dietary intake among Dalmatian dialysis patients. Fifty-five hemodialysis (HD) and twenty peritoneal dialysis (PD) participants were included. For each study participant, data about body composition, anthropometric, laboratory, and clinical parameters were obtained. The Malnutrition Inflammation Score (MIS) and two separate 24-h dietary recalls were used to assess nutritional status and dietary intake. The Nutrient Adequacy Ratio (NAR) and Mean Adequacy Ratio (MAR) were calculated to compare actual dietary intake with recommended intake. Additionally, the estimated 10-year survival was calculated using the Charlson Comorbidity Index. The prevalence of malnutrition according to MIS was 47.3% in HD and 45% in PD participants. Significant differences in fat tissue parameters were found between HD and PD participants, whereas significant differences in hydration status and muscle mass parameters were not found. A significant difference in NAR between HD and PD participants was noticed for potassium and phosphorus intake, but not for MAR. MIS correlated negatively with anthropometric parameters, fat mass, visceral fat level and trunk fat mass, and iron and uric acid in HD participants, whereas no significant correlations were found in PD participants. The estimated 10-year survival correlated with several parameters of nutritional status in HD and PD participants, as well as nutrient intake in HD participants. These results indicate a high prevalence of malnutrition and inadequate dietary intake in the Dalmatian dialysis population which, furthermore, highlights the urgent need for individualized and structural nutritional support.