Rapid Change in Residual Renal Function Decline Is Associated with Lower Survival and Worse Residual Renal Function Preservation in Peritoneal Dialysis Patients

Benefits and Pitfalls of Uraemic Toxin Measurement in Peritoneal Dialysis

Chronic kidney disease is a global health burden with a rising incidence and prevalence in developed and developing nations. Once established, it results in a progressive accumulation of a myriad of uraemic toxins. Peritoneal dialysis (PD) uses the body's peritoneal membrane to remove these toxins across a semipermeable membrane to restore and maintain homeostasis. Traditionally, dialysis adequacy has been measured through clearance of urea and creatinine. However, numerous studies have shown marginal links comparing the clearance of urea and creatinine with clinical outcomes reflected in the recent changes to the ISPD guidelines on dialysis adequacy. Instead, attention has focused on protein-bound uraemic toxins (PBTs). Produced by gut bacteria, these molecules are highly protein-bound and poorly removed by either dialysis or absorptive agents. Elevated concentrations of molecules such as p-cresyl sulfate and indoxyl sulfate have been associated with abnormal cellular function and poor patient outcomes. However, widespread use of these measures to determine dialysis adequacy has been limited by the need for specialized techniques required for measurement. Altering the gut microbiome to reduce generation of PBTs through increased dietary fiber might be an alternate approach to better patient outcomes, with some initial positive reports. This report explores advantages and limitations of measuring uraemic toxins in PD, now and in the foreseeable future.

Early Anuria in Incident Peritoneal Dialysis Patients: Incidence, Risk Factors, and Associated Clinical Outcomes

Rationale & Objective

The development of anuria has been linked to worse clinical outcomes in patients undergoing peritoneal dialysis (PD). Our objective was to investigate the incidence, risk factors, and associated clinical outcomes of anuria within the first year after starting PD.

Study Design

Retrospective cohort study.

Setting & Participants

Patients who started continuous ambulatory peritoneal dialysis at our center between 2006 and 2020 were included and followed up until January 31, 2023.

Exposure

Age, sex, diabetes, temporary hemodialysis, angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II receptor blockers (ARBs), diuretics, baseline urine volume, serum albumin, daily glucose exposure, peritonitis, and incremental PD.

Outcomes

The primary outcome was early anuria, defined as 24-hour urine volume ≤100 mL within the first year of PD initiation. Secondary outcomes included all-cause mortality, cardiovascular disease mortality, technique failure, and peritonitis.

Analytical Approach

Cox proportional hazards model.

Results

A total of 2,592 patients undergoing continuous ambulatory peritoneal dialysis aged 46.7 ± 14.9 years were recruited. Among them, 58.9% were male, and 24.0% had diabetes. Within the first year of PD therapy, 159 (6.13%) patients developed anuria, with a median duration of 7.53 (interquartile range, 3.93-10.0) months. Higher baseline urine volume (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.90-0.97), higher serum albumin (HR, 0.92; 95% CI, 0.88-0.95), having diabetes before PD (HR, 0.57; 95% CI, 0.35-0.92), and prescribed incremental PD (HR, 0.27; 95% CI, 0.14-0.51) were associated with a reduced risk for early anuria, whereas a higher level of daily glucose exposure (HR, 1.01; 95% CI, 1.00-1.01) was identified as a risk factor for early anuria. Subgroup analyses showed that using ACEis or ARBs was linked to a lower risk of early anuria (HR, 0.25; 95% CI, 0.09-0.69) in diabetic patients. Treating early anuria as a time-dependent covariate, early anuria was associated with a higher risk for all-cause mortality (HR, 1.69; 95% CI, 1.23-2.32) and technique failure (HR, 1.43; 95% CI, 1.00-2.04) after adjusting for confounding factors.

Limitations

Single-center and observational study.

Conclusions

Among PD patients at a single center in China, early anuria was relatively uncommon but associated with an increased risk of mortality and PD technique failure. Incremental PD, higher baseline urine output and serum albumin, and lower daily glucose exposure were associated with a lower risk of early anuria. Clinical trials are needed to evaluate the optimal PD techniques to preserve residual kidney function and maximaze outcomes.

Clinical guideline on adequacy and prescription of peritoneal dialysis

In recent years, the meaning of adequacy in peritoneal dialysis has changed. We have witnessed a transition from an exclusive achievement of specific objectives -namely solute clearances and ultrafiltration- to a more holistic approach more focused to on the quality of life of these patients. The purpose of this document is to provide recommendations, updated and oriented to social and health environment, for the adequacy and prescription of peritoneal dialysis. The document has been divided into three main sections: adequacy, residual kidney function and prescription of continuous ambulatory peritoneal dialysis and automated peritoneal dialysis. Recently, a guide on the same topic has been published by a Committee of Experts of the International Society of Peritoneal Dialysis (ISPD 2020). In consideration of the contributions of the group of experts and the quasi-simultaneity of the two projects, references are made to this guide in the relevant sections. We have used a systematic methodology (GRADE), which specifies the level of evidence and the strength of the proposed suggestions and recommendations, facilitating future updates of the document.

Serum uric acid level and all-cause and cardiovascular mortality in peritoneal dialysis patients: A systematic review and dose-response meta-analysis of cohort studies

BACKGROUND

The association between serum uric acid (SUA) and all-cause and cardiovascular disease (CVD) mortality in peritoneal dialysis (PD) patients is controversial. Therefore, we aimed to determine the relationship between SUA and all-cause and CVD mortality in PD patients.

METHOD

Web of Science, EMBASE, PubMed and the Cochrane Library databases were searched from their inception to 7 April 2021. Effect estimates were presented as hazard ratios (HRs) with 95% confidence intervals (95% CIs) and pooled using random effects model.

RESULT

Thirteen cohort studies with 22418 patients were included in this systematic review, of which 9 were included in the meta-analysis. Before switching the reference group, pooled result for the highest SUA category was significantly greater than the median for all-cause mortality (HR = 2.41, 95% CI: 1.37-4.26). After switching the reference group, the highest SUA category did not demonstrate an increased all-cause (HR = 1.40, 95% CI: 0.95-2.05) or CVD (HR = 1.30, 95% CI: 0.72-2.34) mortality compared with the lowest SUA category. Dose-response analysis suggested a nonlinear association between SUA and all-cause mortality risk (Pnonlinearity = 0.002).

CONCLUSION

This meta-analysis didn't find the relationship between SUA levels and all-cause and CVD mortality risk in PD patients. More rigorously designed studies are warranted in the future.

Impact of dialysis modality on major adverse cardiovascular events and all-cause mortality: a national population-based study

BACKGROUND

Only few studies with inconsistent results comparing the relative risk of cardiac mortality between peritoneal dialysis (PD) and hemodialysis (HD). Switches between renal replacement therapy (RRT) modalities render objective assessment of survival benefits a greater challenge.

METHODS

Data were retrieved from Taiwan's National Health Insurance Database from 1 January 2006 to 31 December 2015. We included 13 662 and 41 047 long-term dialysis patients in a propensity score matching study design and a time-varying study design, respectively, to compare major adverse cardiovascular events (MACEs) between patients receiving PD and HD. We also included 109 256 dialysis patients to compare the all-cause mortality among different RRT modalities.

RESULTS

For MACE, the hazard ratio (HR) for PD patients compared to HD patients was 0.95 [95% confidence interval (CI) 0.89-1.02] in the propensity score study design and 1.06 (95% CI 1.01-1.12) in the time-varying study design. For all-cause mortality, the HR for PD patients compared to HD patients was 1.09 (95% CI 1.05-1.13) in the propensity score study design and 1.13 (95% CI 1.09-1.17) in the time-varying study design. The HR for death was higher at a level of statistical significance for females (1.21, 95% CI 1.15-1.28), patients ≥65 years old (1.30, 95% CI 1.24-1.36) and diabetes mellitus (DM; 1.28, 95% CI 1.22-1.34).

CONCLUSIONS

The HR for MACE is significantly higher among PD patients in time-varying design analysis. In addition, all-cause mortality was higher in PD patients compared to patients with HD, especially in those who were aged ≥65 years, female or DM.

Comparison of Cardiovascular Outcomes by Dialysis Modality: A Systematic Review and Meta-Analysis

Debates exist regarding the merit of starting one dialysis modality over the other for improved cardiovascular outcomes. Five previously published prospective and retrospective cohort studies have reported inconsistent conclusions on this topic. The aim of this systematic review and meta-analysis is to evaluate the influence initiation of hemodialysis (HD) vs peritoneal dialysis (PD) may have on the relative risk (RR) of subsequent development of adverse cardiovascular events (ACVE) in patients with end-stage renal disease (ESRD). Of the 518 records identified, 5 cohort studies, assessing a total of 47,062 patients were included in the meta-analysis. With regard to the subsequent development of ACVE following initiation on the different dialysis modalities, the pooled RR was found to be non-significant. Peritoneal dialysis is a suitable and cost-effective alternative to HD for ESRD patients at risk of cardiovascular disease.

Risk factors for loss of residual renal function in children with end-stage renal disease undergoing automatic peritoneal dialysis

BACKGROUND

This study analysed children with end-stage renal disease treated with automated peritoneal dialysis (APD) in our centre to explore the risk factors associated with residual renal function (RRF) loss.

METHODS

Children treated with APD as the initial renal replacement therapy regimen from January 2008 to December 2016 were included. All the children had a daily urine volume of ≥100 ml/m² when APD was initiated and a dialysis follow-up time of ≥12 months. A daily urine volume of <100 ml/m² after 12 months of APD treatment was defined as loss of RRF. Possible risk factors that may be associated with RRF loss were analysed.

RESULTS

A total of 66 children were included in the study. After 12 months of APD treatment, the daily urine volume decreased by 377.45 ± 348.80 ml/m², the residual glomerular filtration rate decreased by 6.39 ± 3.69 ml/min/1.73 m² and 29 of the patients (43.9%) developed RRF loss. The higher risk of RRF loss after 1 year of APD treatment was most pronounced in patients with daily urine volume of ≤400 ml/m² before treatment, higher glucose exposure and higher ultrafiltration volume, while the lower risk of RRF loss was in patients with administration of diuretics. Each increase of 1 g/m²/day glucose exposure was associated with a 5% increase in RRF loss (odds ratio (OR) 1.05, p = 0.023) and each increase of 1 ml/m²/day ultrafiltration volume was associated with a 1% increase in RRF loss (OR 1.01, p = 0.013).

CONCLUSION

In children undergoing APD, the risk for loss of RRF is associated with low urine volume at the start of APD, high glucose loading and high peritoneal ultrafiltration volume, while preservation of RRF is associated with the usage of diuretics.

2005 Guidelines on targets for solute and fluid removal in adults being treated with chronic peritoneal dialysis: 2019 Update of the literature and revision of recommendations

BACKGROUND

The International Society for Peritoneal Dialysis guidelines for small solute clearance and fluid removal in peritoneal dialysis (PD) were published in 2005. The aim of this article is to update those guidelines by reviewing the literature that supported those guidelines and examining publications since then.

METHODS

An extensive search of publications was performed through electronic databases and a hand search through reference lists from the existing guideline and selected articles.

RESULTS

There have been no prospective intervention trials to inform the area of small solute clearance in PD since the publication of the original guideline in 2005. The trials to date are largely limited to a few prospective cohort studies and retrospective studies. These have, however, consistently demonstrated that residual renal function (RRF) is more often associated with patient outcome than peritoneal clearance. One of the few randomised controlled trials performed in this area does suggest that a weekly Kt/V of 2.27 ± 0.02 provides no statistically significant survival advantage over a weekly Kt/V of 1.80 ± 0.02. The lower limit of Kt/V is unknown but there is weak evidence to suggest that anuric people doing PD should have a weekly Kt/V of at least 1.7.

CONCLUSIONS

There continues to be very poor evidence in the area of small solute clearance and fluid removal in PD. The evidence that exists suggests that RRF is more important than peritoneal clearance and that there appears to be no survival advantage in aiming for a weekly Kt/V >1.70.

Clinical outcomes of incident peritoneal dialysis patients coming from kidney transplantation program: A case-control study

Introduction

Brazil ranks second in the absolute number of transplantations in the world. Despite improvements in graft survival, many patients will progress to graft loss and return to dialysis. Concerns exist regarding adverse clinical outcomes in this population when undergone peritoneal dialysis (PD).

Objective

To compare the occurrence of mortality, technique failure, and peritonitis among incident patients in PD coming from either Tx or pre-dialysis treatment.

Methodology

A retrospective study in which 47 adult patients with Tx failure (Tx group) were matched for age, gender, diabetes mellitus (DM), modality and start year of PD, with 1:1 predialysis patient (nTx group). The Fine-Gray competing risk model was used to analyze mortality and technique failure.

Results

Compared to nTx, the Tx group had a lower body mass index, serum potassium, and albumin concentrations. A higher ferritin level, transferrin saturation and the number of patients with positive serology for viral hepatitis were also observed in the Tx group. In the multivariate analysis, patients of the Tx group had 4.4-times higher risk of death (p = 0.007), with infection as the main cause. Technique failure and peritonitis were similar in both groups.

Conclusion

Previous Tx is a risk factor for mortality but not for technique failure or peritonitis in incident patients on a PD program.

Prescribing Hemodialysis or Hemodiafiltration: When One Size Does Not Fit All the Proposal of a Personalized Approach Based on Comorbidity and Nutritional Status

There is no simple way to prescribe hemodialysis. Changes in the dialysis population, improvements in dialysis techniques, and different attitudes towards the initiation of dialysis have influenced treatment goals and, consequently, dialysis prescription. However, in clinical practice prescription of dialysis still often follows a "one size fits all" rule, and there is no agreed distinction between treatment goals for the younger, lower-risk population, and for older, high comorbidity patients. In the younger dialysis population, efficiency is our main goal, as assessed by the demonstrated close relationship between depuration (tested by kinetic adequacy) and survival. In the ageing dialysis population, tolerance is probably a better objective: "good dialysis" should allow the patient to attain a stable metabolic balance with minimal dialysis-related morbidity. We would like therefore to open the discussion on a personalized approach to dialysis prescription, focused on efficiency in younger patients and on tolerance in older ones, based on life expectancy, comorbidity, residual kidney function, and nutritional status, with particular attention placed on elderly, high-comorbidity populations, such as the ones presently treated in most European centers. Prescription of dialysis includes reaching decisions on the following elements: dialysis modality (hemodialysis (HD) or hemodiafiltration (HDF)); type of membrane (permeability, surface); and the frequency and duration of sessions. Blood and dialysate flow, anticoagulation, and reinfusion (in HDF) are also briefly discussed. The approach described in this concept paper was developed considering the following items: nutritional markers and integrated scores (albumin, pre-albumin, cholesterol; body size, Body Mass Index (BMI), Malnutrition Inflammation Score (MIS), and Subjective Global Assessment (SGA)); life expectancy (age, comorbidity (Charlson Index), and dialysis vintage); kinetic goals (Kt/V, normalized protein catabolic rate (n-PCR), calcium phosphate, parathyroid hormone (PTH), beta-2 microglobulin); technical aspects including vascular access (fistula versus catheter, degree of functionality); residual kidney function and weight gain; and dialysis tolerance (intradialytic hypotension, post-dialysis fatigue, and subjective evaluation of the effect of dialysis on quality of life). In the era of personalized medicine, we hope the approach described in this concept paper, which requires validation but has the merit of providing innovation, may be a first step towards raising attention on this issue and will be of help in guiding dialysis choices that exploit the extraordinary potential of the present dialysis "menu".

Does Residual Renal Function Have a Beneficial Effect on Patient and Technique Survival in Peritoneal Dialysis Patients?

Objectives:

Residual renal function (RRF) at the initiation of peritoneal dialysis (PD) therapy can be a predictor of survival in stable PD patients. The aim of the present study was to investigate PD patients regarding the effect of baseline RRF on patient and technique survival.

Methods:

Urine output at the beginning of PD therapy was evaluated retrospectively in 202 PD patients. Patients were divided into two groups: patients with anuria (urine output ≤100 ml/day) and patients without anuria (urine output >100 ml/day).

Results:

The number of patients with anuria was 58 in which 38 patients were females. The mean age of the patients was 42.8±14.9 years. The mean follow-up period was 44.2±35 months. Twelve percent of patients with anuria had history of hemodialysis (HD).

One hundred forty-four had no anuria (68 females, mean age 43.7±14.5 years, mean follow-up period 39.6±26.1 months, mean urine volume 592±442 ml). Twenty-three patients had received HD therapy before. Sixty-five had anuria in the following 22.5±19.6 months.

At the beginning of therapy, systolic and diastolic blood pressures were lower in patients with oliguria than in patients without oliguria (p<0.001), but C-reactive protein (p=0.004) and ferritin (p<0.001) levels were higher. There was no difference between two groups regarding the other parameters (age, follow-up periods, presence of diabetes, ultrafiltration volumes, albumin, hemoglobin, calcium phosphorus product, parathormone, and Kt/V levels) (p>0.05).

The peritonitis rate was one episode per 28.2 versus 30 patient-months for the anuric and non-anuric groups, respectively (p>0.05).

For Kaplan–Meier survival analysis, the mean technique survival rates at 1 and 3 years were 97% and 86.6% in patients without anuria and 94% and 85.3% in patients with anuria, respectively. The 5-year technique survival rates according to residual volume states were not statistically significant with log-rank test (p>0.05).

The 1-, 3-, and 5-year survival rates were 96.9%, 89.6%, and 86.5% in patients without anuria, respectively, whereas they were 87.3%, 77.3%, and 53.7% in patients with anuria, respectively. The 5-year survival rates according to residual volume states were statistically significant (p<0.05).

Conclusion:

RRF at the beginning of PD has an important and positive impact on patient survival in PD patients. Peritonitis rates and technique survival were not different for patients with anuria and without anuria.

Association Between Comprehensive Nutritional Scoring System (CNSS) and Outcomes of Continuous Ambulatory Peritoneal Dialysis Patients

BACKGROUND/AIMS

The presence of protein-energy wasting (PEW) among dialysis patients is a crucial risk factor for outcomes. The complicated pathogenesis of PEW makes it difficult to assess and treat. This single-center retrospective study focuses on the association between nutritional markers and the outcomes of continuous ambulatory peritoneal dialysis(CAPD) patients, aiming to establish a practical comprehensive nutritional scoring system for CAPD patients.

METHODS

924 patients who initiated peritoneal dialysis in our center from January 1st,2005 to December 31st,2015 were enrolled. Comprehensive nutritional scoring system(CNSS) was based on items including SGA, BMI, ALB, TC, MAC and TSF. We divide patients into 3 groups according to their CNSS score. Outcomes including mortality, hospitalization days and hospitalization frequency were compared between 3 grades.

RESULTS

The CNSS grade correlated significantly with hospitalization days (P<0.05). Both categorized CNSS grade (HR:0.56; 95% CI:0.41-0.78; P = 0.001) and continuous CNSS score (HR:0.87; 95% CI: 0.80-0.94; P = 0.001) independently protect PD patients from all-cause mortality.

CONCLUSION

CNSS provides an integrated scoring system with significant associations with hospitalization and mortality in PD patients. The CNSS grade differentiates patients with malnutritional risk and independently predicts high risk of morbidity and mortality.