Hyponatraemia and fluid overload are associated with higher risk of mortality in dialysis patients

Understanding Health Literacy in Fluid Management in Individuals Receiving Haemodialysis: A Directed Qualitative Content Analysis

AIMS

To describe the perspectives of individuals receiving haemodialysis regarding health literacy in fluid management.

DESIGN

A qualitative descriptive approach using directed content analysis of interviews from an explanatory mixed methods study.

METHODS

Semi-structured individual interviews were conducted from September 2020 to February 2021 with 28 individuals receiving haemodialysis who had attended a prior quantitative study. A directed qualitative content analysis approach was used to identify categories and subcategories emerging from the data.

RESULTS

Six categories of health literacy were identified: (1) active health management, (2) engagement with healthcare providers, (3) understanding and support from healthcare providers, (4) social support, (5) health information literacy and (6) navigation of the healthcare system.

CONCLUSIONS

Based on their real-life experience, individuals receiving haemodialysis have unique health literacy needs regarding fluid management. A comprehensive understanding of these unique needs is crucial in creating person-centered interventions to address inadequate fluid restriction.

IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE

Interventions to address inadequate fluid restriction should be person-centered, considering each individual's unique health literacy needs. This involves conducting a comprehensive assessment of individuals' health literacy needs, empowering individuals to actively engage in health, engaging the entire support network and facilitating health information literacy in line with individuals' preferences.

IMPACT

This study offers detailed insights into the health literacy needs related to fluid management in individuals undergoing haemodialysis. The findings could inform the development of person-centered fluid management strategies for these individuals.

REPORTING METHOD

We adhered to the Consolidated Criteria for Reporting Qualitative Research checklist.

PATIENT OR PUBLIC CONTRIBUTION

No patient or public contribution.

Associations of Abnormal Fluid Status, Plasma Sodium Disorders, and Low Dialysate Sodium with Mortality in Patients on Hemodialysis

Background

Abnormal fluid and plasma sodium concentrations are established prognostic factors for patients on hemodialysis. However, the cumulative effects of abnormal salt and water and potential effect modifications and the effect of dialysate sodium remain incompletely understood.

Methods

The study followed 68,196 patients on incident hemodialysis from 875 dialysis clinics in 25 countries over 10 years (2010–2020) investigating dose-response patterns between cumulative exposure time of fluid overload/depletion (measured by bioimpedance spectroscopy using the Fresenius Body Composition Monitor), abnormal plasma sodium levels, low dialysate sodium, and all-cause mortality. We calculated time-varying cumulative exposure (in months) of relative fluid overload (any degree; >7% or severe; >13 or >15% in women or men, respectively) and fluid depletion (<−7%), hypo- or hypernatremia (sodium <135 or >145 mmol/L, respectively), low dialysate sodium (≤138 mmol/L), and estimated hazard ratios for all-cause mortality using a multivariable Cox model.

Results

Of 2,123,957 patient-months, 61% were spent in any degree of fluid overload, 4% in fluid depletion, 11% in hyponatremia, and 1% in hypernatremia. Any degree of fluid overload was associated with higher all-cause mortality (hazard ratio peak at 3.42 [95% confidence intervals, 3.12 to 3.75] relative to no exposure), and this association with all-cause mortality seemed to be stronger with severe fluid overload. The risk pattern associated with hyponatremia was approximately linear in the first four patient-months and then plateaued after the fourth patient-month. We did not observe effect modification between fluid overload and hyponatremia.

Conclusions

Even mild fluid overload was associated with higher mortality in patients on hemodialysis. Whether more stringent fluid management results in clinical improvement requires further investigation.

Effect of Dialysate and Plasma Sodium on Mortality in a Global Historical Hemodialysis Cohort

SIGNIFICANCE STATEMENT

This large observational cohort study aimed to investigate the relationship between dialysate and plasma sodium concentrations and mortality among maintenance hemodialysis patients. Using a large multinational cohort of 68,196 patients, we found that lower dialysate sodium concentrations (≤138 mmol/L) were independently associated with higher mortality compared with higher dialysate sodium concentrations (>138 mmol/L). The risk of death was lower among patients exposed to higher dialysate sodium concentrations, regardless of plasma sodium levels. These results challenge the prevailing assumption that lower dialysate sodium concentrations improve outcomes in hemodialysis patients. The study confirms that until robust evidence from randomized trials that are underway is available, nephrologists should remain cautious in reconsideration of dialysate sodium prescribing practices to optimize cardiovascular outcomes and reduce mortality in this population.

BACKGROUND

Excess mortality in hemodialysis (HD) patients is largely due to cardiovascular disease and is associated with abnormal fluid status and plasma sodium concentrations. Ultrafiltration facilitates the removal of fluid and sodium, whereas diffusive exchange of sodium plays a pivotal role in sodium removal and tonicity adjustment. Lower dialysate sodium may increase sodium removal at the expense of hypotonicity, reduced blood volume refilling, and intradialytic hypotension risk. Higher dialysate sodium preserves blood volume and hemodynamic stability but reduces sodium removal. In this retrospective cohort, we aimed to assess whether prescribing a dialysate sodium ≤138 mmol/L has an effect on survival outcomes compared with dialysate sodium >138 mmol/L after adjusting for plasma sodium concentration.

METHODS

The study population included incident HD patients from 875 Fresenius Medical Care Nephrocare clinics in 25 countries between 2010 and 2019. Baseline dialysate sodium (≤138 or >138 mmol/L) and plasma sodium (<135, 135-142, >142 mmol/L) concentrations defined exposure status. We used multivariable Cox regression model stratified by country to model the association between time-varying dialysate and plasma sodium exposure and all-cause mortality, adjusted for demographic and treatment variables, including bioimpedance measures of fluid status.

RESULTS

In 2,123,957 patient-months from 68,196 incident HD patients with on average three HD sessions per week dialysate sodium of 138 mmol/L was prescribed in 63.2%, 139 mmol/L in 15.8%, 140 mmol/L in 20.7%, and other concentrations in 0.4% of patients. Most clinical centers (78.6%) used a standardized concentration. During a median follow-up of 40 months, one third of patients ( n =21,644) died. Dialysate sodium ≤138 mmol/L was associated with higher mortality (multivariate hazard ratio for the total population (1.57, 95% confidence interval, 1.25 to 1.98), adjusted for plasma sodium concentrations and other confounding variables. Subgroup analysis did not show any evidence of effect modification by plasma sodium concentrations or other patient-specific variables.

CONCLUSIONS

These observational findings stress the need for randomized evidence to reliably define optimal standard dialysate sodium prescribing practices.