Predictors of encapsulated peritoneal sclerosis in patients undergoing peritoneal dialysis using neutral-pH dialysate

BACKGROUND

Encapsulated peritoneal sclerosis (EPS) is a serious complication in patients undergoing peritoneal dialysis (PD). Neutral-pH dialysate is associated with less peritoneal damage and a lower incidence of EPS than conventional PD solution. However, monitoring for peritoneal damage and predicting EPS remain important during PD therapy.

METHODS

We measured the mesothelial cell area, dialysate-to-plasma ratio of creatinine after 4 h, and concentrations of the potential biological markers effluent fibrin degradation products (eFDPs), cancer antigen-125, and interleukin-6 in the effluent dialysate from patients who had been undergoing PD therapy for > 5 years in our hospital. These biomarkers were obtained from the drainage fluid of the final measurement of peritoneal equilibration testing before withdrawal from PD therapy. The concentrations of these potential biomarkers were measured in 39 patients who withdrew from PD therapy and were enrolled in the study.

RESULTS

Three participants developed EPS after withdrawing PD. The dialysate-to-plasma ratio of creatinine, area of mesothelial cells, and interleukin-6 appearance rate in participants who developed EPS tended to be higher than those in patients who did not, but there were no significant differences. Significantly more eFDPs were in participants who developed EPS than in those who did not (138.5 ± 15.1 vs. 32.9 ± 7.4 µg/mL, P = 0.002). There was no difference in the cancer antigen-125 appearance rate between the groups. A cut-off value of eFDPs ≥ 119.1 µg/mL was optimal for predicting EPS (P = 0.006, specificity = 0.972, sensitivity = 1.000).

CONCLUSION

This study shows that eFDPs may be a useful biological marker for predicting EPS in patients undergoing PD using neutral-pH dialysate.

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.

Sterile inflammation of peritoneal membrane caused by peritoneal dialysis: focus on the communication between immune cells and peritoneal stroma

Peritoneal dialysis is a widely used method for treating kidney failure. However, over time, the peritoneal structure and function can deteriorate, leading to the failure of this therapy. This deterioration is primarily caused by infectious and sterile inflammation. Sterile inflammation, which is inflammation without infection, is particularly concerning as it can be subtle and often goes unnoticed. The onset of sterile inflammation involves various pathological processes. Peritoneal cells detect signals that promote inflammation and release substances that attract immune cells from the bloodstream. These immune cells contribute to the initiation and escalation of the inflammatory response. The existing literature extensively covers the involvement of different cell types in the sterile inflammation, including mesothelial cells, fibroblasts, endothelial cells, and adipocytes, as well as immune cells such as macrophages, lymphocytes, and mast cells. These cells work together to promote the occurrence and progression of sterile inflammation, although the exact mechanisms are not fully understood. This review aims to provide a comprehensive overview of the signals from both stromal cells and components of immune system, as well as the reciprocal interactions between cellular components, during the initiation of sterile inflammation. By understanding the cellular and molecular mechanisms underlying sterile inflammation, we may potentially develop therapeutic interventions to counteract peritoneal membrane damage and restore normal function.

Glucose degradation products in peritoneal dialysis solution impair angiogenesis by dysregulating angiogenetic factors in endothelial and vascular smooth muscle cells

BACKGROUND

The accumulation of glucose degradation products (GDPs) during peritoneal dialysis (PD) can lead to immature angiogenesis in the peritoneum. However, the effect of GDPs on angiogenesis, at concentrations observed in dialysate effluent, has not been widely investigated. We do not know how the inflammation observed in PD-related peritonitis affects angiogenesis of the peritoneum.

METHODS

Human umbilical vessel endothelial cells (HUVEC) and human umbilical aortic smooth muscle cells (HUASMC) were used to examine the response to the three main GDPs found in peritoneal dialysate (methylglyoxal (MGO), 3-deoxyglucosone (3-DG), and 5-hydroxymethylfurfural (5-HMF). Supernatant from lipopolysaccharide (LPS)-activated murine macrophage cell lines (RAW 264.7 cells) were used to stimulate angiogenesis in the peritoneum. Changes in the expression of vascular endothelial growth factor-A (VEGF-A) and platelet-derived growth factor B (PDGFB) in HUVEC, and PDGF-receptor beta (PDGF-Rβ) in HUASMC, were examined by real-time PCR, Western blot, and ELISA.

RESULTS

In HUVECs, the expression of PDGFB mRNA and protein were decreased by exposure to MGO, 3-DG, and 5-HMF at concentrations observed in dialysate effluent. A subsequent decrease in secreted PDGF-BB was observed. In HUASMCs, MGO and 5-HMF increased the expression of VEGF-A mRNA and protein, while 5-HMF decreased the expression of PDGF-Rβ. VEGF-A is upregulated, and PDGF-Rβ is downregulated, by conditioned medium of LPS-stimulated macrophages in HUASMCs.

CONCLUSIONS

The GDPs of PD effluent cause an imbalance of angiogenic factors in endothelial cells and vascular smooth muscle cells that may lead to immature angiogenesis in the peritoneum.

Secretory activity of the coronary artery endothelial cells in conditions of the peritoneal dialysis

Introduction

Endothelial dysfunction is frequent in patients treated with peritoneal dialysis and may lead to cardiac complications. We evaluated the effect of effluent dialysates and serum on the function of coronary artery endothelial cells (CAEC).

Methods

Human CAEC in in vitro culture were exposed to serum and dialysates from 24 patients treated with continuous ambulatory peritoneal dialysis (CAPD) and secretion of interleukin-6 (IL6), von Willebrand factor (vWF), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) were measured. Modulation of the secretory activity of CAEC by Sulodexide, mixture of glycosaminoglycans: heparin sulfate and dermatan sulfate, was studied.

Results

Serum from CAPD patients stimulated synthesis of IL6 (+93%), vWF (+18%), and PAI-1 (+20%) and did not change t-PA secretion in CAEC. Dialysates stimulated secretion of IL6 (+89%), vWF (+29%), and PAI-1 (+31%) and did not change t-PA synthesis. Dialysates collected in 12 patients after 6 months more strongly stimulated synthesis of IL6 (+37%) and PAI-1 (+7%). Sulodexide suppressed the secretory activity of CAEC stimulated by the studied sera: IL6 (–38%), vWF (–19%), t-PA (–13%), and PAI-1 (–12%).

Conclusions

Serum and the dialysate from CAPD patients induce inflammatory and prothrombotic reaction in coronary arterial endothelial cells. The general pattern of the observed effects for serum and dialysates was similar but the intensity of the effects was not identical. Sulodexide reduced these effects.

Incremental peritoneal dialysis is a safe and feasible prescription in incident patients with preserved residual kidney function

BACKGROUND

Incremental peritoneal dialysis (PD) is recommended as a component of high-quality care by the international society for PD; however, its feasibility and clinical outcomes have not been widely reported. The aim of this study is to describe our experience with incremental PD.

METHODS

This was a retrospective cohort study of incident PD patients at Eastern Health between 2015 and 2019. Patients who stopped PD within 30 days were excluded. Incremental PD was defined in CAPD as using <8 L/day of exchange volume and in automated PD as dialysing without a last fill. Dialysis modality accorded with patient and physician preferences.

RESULTS

The 96 patients were included in this study; 54 with incremental PD. Compared to full-dose PD, incremental PD patients were more likely to be female, had less comorbid diabetes (28% vs. 52%) and higher residual kidney function (RKF) (Kt/V 2.0 ± 0.7 vs. 1.4 ± 0.7). Age, BMI and starting eGFR did not differ between groups. Incremental PD exposed patients to lower exchange volumes (4.4 ± 2.1 vs. 8.5 ± 1.1 L/day), glucose load (46 ± 41 g/day vs. 119 ± 46) and was associated with a longer peritonitis-free survival. PD technique survival, rates of peritonitis or hospitalization were comparable between groups. Predictors for longer incremental PD use included older age and higher starting eGFR.

CONCLUSIONS

Incremental PD is a feasible, goal-directed initial prescription in patients with RKF with comparable peritonitis rates and technique survival. Validation of this prescription in prospective studies is warranted.

Outcome measures for technique survival reported in peritoneal dialysis: A systematic review

BACKGROUND

Peritoneal dialysis (PD) technique survival is an important outcome for patients, caregivers and health professionals, however, the definition and measures used for technique survival vary. We aimed to assess the scope and consistency of definitions and measures used for technique survival in studies of patients receiving PD.

METHOD

MEDLINE, EMBASE and CENTRAL databases were searched for randomised controlled studies (RCTs) conducted in patients receiving PD reporting technique survival as an outcome between database inception and December 2019. The definition and measures used were extracted and independently assessed by two reviewers.

RESULTS

We included 25 RCTs with a total of 3645 participants (41-371 per trial) and follow up ranging from 6 weeks to 4 years. Terminology used included 'technique survival' (10 studies), 'transfer to haemodialysis (HD)' (8 studies) and 'technique failure' (7 studies) with 17 different definitions. In seven studies, it was unclear whether the definition included transfer to HD, death or transplantation and eight studies reported 'transfer to HD' without further definition regarding duration or other events. Of those remaining, five studies included death in their definition of a technique event, whereas death was censored in the other five. The duration of HD necessary to qualify as an event was reported in only four (16%) studies. Of the 14 studies reporting causes of an event, all used a different list of causes.

CONCLUSION

There is substantial heterogeneity in how PD technique survival is defined and measured, likely contributing to considerable variability in reported rates. Standardised measures for reporting technique survival in PD studies are required to improve comparability.

Comparison between standard single chamber versus dual chamber low glucose degradation product peritoneal dialysis fluids

Dual chamber (DC) peritoneal dialysis (PD) dialysates contain fewer glucose degradation products (GDPs), so potentially reducing advanced glycosylation end products (AGEs), which have been reported to increase inflammation and cardiovascular risk. We wished to determine whether use of DC dialysates resulted in demonstrable patient benefits. Biochemical profiles, body composition, muscle strength, and skin autofluorescence measurements of tissue AGEs (SAF) were compared in patients using DC and standard single chamber dialysates. We studied 263 prevalent PD patients from 2 units, 62.4% male, mean age 61.8 ± 16.1 years, 78 (29.7%) used DC dialysates. DC patients were younger (55.9 ± 16.4 vs. 64.2 ± 15.4 years), and more had lower Davies comorbidity score (median 1 (0-1) vs. 1 (0, 2)), slower peritoneal transport (D/P creatinine 0.67 ± 0.12 vs. 0.73 ± 0.13), greater extracellular water-to-total body water (ECW/TBW) ratio (0.46 ± 0.05 vs. 0.42 ± 0.06), all P < .001, whereas there were no differences in the duration of PD (median (IQR) 19 (8-32) vs. 14 (8-23) months), residual renal function (Kt/V_urea 0.71 ± 0.71 vs. 0.87 ± 0.82), urine volume (642 (175-1200) vs. 648 (300-1200) mL/day), hand grip strength (26.9 ± 10.5 vs. 24.9 ± 10.7 kg), C-reactive protein (4(1-10) vs. 4(2-12) mg/L), and SAF (median 3.60 (3.02, 4.40) vs. 3.50 (3.00, 4.23)) AU. In our cross-sectional observational study, we were not able to show a demonstrable advantage for using low GDP dialysates over conventional glucose dialysates, in terms of biochemical profiles, residual renal function, muscle strength, or tissue AGE deposition. More patients using low GDP dialysates were slower peritoneal transporters with higher ECW/TBW ratios.

Endothelial dysfunction and low-grade inflammation in the transition to renal replacement therapy

Introduction

End-stage renal disease (ESRD) strongly associates with cardiovascular disease (CVD) risk. This risk is not completely mitigated by renal replacement therapy. Endothelial dysfunction (ED) and low-grade inflammation (LGI) may contribute to the increased CVD risk. However, data on serum biomarkers of ED and LGI during the transition to renal replacement therapy (dialysis and kidney transplantation) are scarce.

Methods

We compared serum biomarkers of ED and LGI between 36 controls, 43 participants with chronic kidney disease (CKD) stage 5 non-dialysis (CKD5-ND), 20 participants with CKD stage 5 hemodialysis (CKD5-HD) and 14 participants with CKD stage 5 peritoneal dialysis (CKD5-PD). Further, in 34 and 15 participants repeated measurements were available during the first six months following dialysis initiation and kidney transplantation, respectively. Serum biomarkers of ED (sVCAM-1, E-selectin, P-selectin, thrombomodulin, sICAM-1, sICAM-3) and LGI (hs-CRP, SAA, IL-6, IL-8, TNF-α) were measured with a single- or multiplex array detection system based on electro-chemiluminescence technology.

Results

In linear regression analyses adjusted for potential confounders, participants with ESRD had higher levels of most serum biomarkers of ED and LGI than controls. In addition, in CKD5-HD levels of serum biomarkers of ED and LGI were largely similar to those in CKD5-ND. In contrast, in CKD5-PD levels of biomarkers of ED were higher than in CKD5-ND and CKD5-HD. Similarly, in linear mixed model analyses sVCAM-1, thrombomodulin, sICAM-1 and sICAM-3 increased after PD initiation. In contrast, incident HD patients showed an increase in sVCAM-1, P-selectin and TNF-α, but a decline of hs-CRP, SAA and IL-6. Further, following kidney transplantation sVCAM-1, thrombomodulin, sICAM-3 and TNF-α were lower at three months post-transplantation and remained stable in the three months thereafter.

Conclusions

Levels of serum biomarkers of ED and LGI were higher in ESRD as compared with controls. In addition, PD initiation and, less convincingly, HD initiation may increase levels of selected serum biomarkers of ED and LGI on top of uremia per se. In contrast to dialysis, several serum biomarkers of ED and LGI markedly declined following kidney transplantation.

Comparison of skin autofluorescence, a marker of tissue advanced glycation end-products in peritoneal dialysis patients using standard and biocompatible glucose containing peritoneal dialysates

BACKGROUND

Heat sterilization of peritoneal dialysis (PD) dialysates leads to the generation of advanced glycation products (AGE), which can then deposit in the skin and be measured by skin autofluorescence (SAF). Newer biocompatible dual chamber dialysates contain less AGE. We wished to determine whether the use of these newer dialysates resulted in lower SAF.

METHODS

Skin autofluorescence was measured using the AGE reader, which directs ultraviolet light, intensity range 300-420 nm (peak 370 nm) in patients established on PD for >3 months using glucose containing dialysates.

RESULTS

We screened 196 consecutive patients, and measured SAF in 150; 86 (57.3%) male, median age 62 (53-71) years, median duration of PD treatment 17 (8.6-34.3) months. The median SAF was 3.48 (2.92-4.26) AU. The median SAF in the 57 (38%) patients prescribed biocompatible dual chamber bag dialysates was 3.39 (2.69-3.98) versus 3.5 (3.05-4.54) for those using standard dialysates (P = 0.044). Although prescription of biocompatible fluids was associated with SAF on univariate analysis, but not on multivariable testing, SAF was independently associated with Stoke-Davies co-morbidity grade (β 0.045, 95% confidence limits (CL) 0.015-0.075, P = 0.002), log duration of PD therapy (β 0.051, CL 0.001-0.101, P = 0.045), white ethnicity (β 0.066, CL 0.028-0.104, P = 0.001), and negatively with serum albumin (β -0.006, CL -0.008 to -0.004, P = 0.014).

CONCLUSION

Although SAF was lower in PD patients prescribed biocompatible dual chamber dialysates, on multivariable testing these dialysates were not independently associated with SAF. Other factors than PD fluid AGE content appear more important in determining SAF.

Biocompatible dialysis fluids for peritoneal dialysis

BACKGROUND

Biocompatible peritoneal dialysis (PD) solutions, including neutral pH, low glucose degradation product (GDP) solutions and icodextrin, have previously been shown to favourably influence some patient-level outcomes, albeit based on generally sub-optimal quality studies. Several additional randomised controlled trials (RCT) evaluating biocompatible solutions in PD patients have been published recently. This is an update of a review first published in 2014.

OBJECTIVES

This review aimed to look at the benefits and harms of biocompatible PD solutions in comparison to standard PD solutions in patients receiving PD.

SEARCH METHODS

The Cochrane Kidney and Transplant Specialised Register was searched up to 12 February 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Specialised Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All RCTs and quasi-RCTs in adults and children comparing the effects of biocompatible PD solutions (neutral pH, lactate-buffered, low GDP; neutral pH, bicarbonate(± lactate)-buffered, low GDP; glucose polymer (icodextrin)) in PD were included. Studies of amino acid-based solutions were excluded.

DATA COLLECTION AND ANALYSIS

Two authors extracted data on study quality and outcomes. Summary effect estimates were obtained using a random-effects model, and results were expressed as risk ratios and 95% confidence intervals (CI) for categorical variables, and mean differences (MD) or standardised mean differences (SMD) and 95% CI for continuous variables.

MAIN RESULTS

This review update included 42 eligible studies (3262 participants), including six new studies (543 participants). Overall, 29 studies (1971 participants) compared neutral pH, low GDP PD solution with conventional PD solution, and 13 studies (1291 participants) compared icodextrin with conventional PD solution. Risk of bias was assessed as high for sequence generation in three studies, allocation concealment in three studies, attrition bias in 21 studies, and selective outcome reporting bias in 16 studies.Neutral pH, low GDP versus conventional glucose PD solutionUse of neutral pH, low GDP PD solutions improved residual renal function (RRF) preservation (15 studies, 835 participants: SMD 0.19, 95% CI 0.05 to 0.33; high certainty evidence). This approximated to a mean difference in glomerular filtration rate of 0.54 mL/min/1.73 m2 (95% CI 0.14 to 0.93). Better preservation of RRF was evident at all follow-up durations with progressively greater preservation observed with increasing follow up duration. Neutral pH, low GDP PD solution use also improved residual urine volume preservation (11 studies, 791 participants: MD 114.37 mL/day, 95% CI 47.09 to 181.65; high certainty evidence). In low certainty evidence, neutral pH, low GDP solutions may make little or no difference to 4-hour peritoneal ultrafiltration (9 studies, 414 participants: SMD -0.42, 95% CI -0.74 to -0.10) which approximated to a mean difference in peritoneal ultrafiltration of 69.72 mL (16.60 to 122.00 mL) lower, and may increase dialysate:plasma creatinine ratio (10 studies, 746 participants: MD 0.01, 95% CI 0.00 to 0.03), technique failure or death compared with conventional PD solutions. It is uncertain whether neutral pH, low GDP PD solution use led to any differences in peritonitis occurrence, hospitalisation, adverse events (6 studies, 519 participants) or inflow pain (1 study, 58 participants: RR 0.51, 95% CI 0.24 to 1.08).Glucose polymer (icodextrin) versus conventional glucose PD solutionIn moderate certainty evidence, icodextrin probably reduced episodes of uncontrolled fluid overload (2 studies, 100 participants: RR 0.30, 95% CI 0.15 to 0.59) and augmented peritoneal ultrafiltration (4 studies, 102 participants: MD 448.54 mL/d, 95% CI 289.28 to 607.80) without compromising RRF (4 studies, 114 participants: SMD 0.12, 95% CI -0.26 to 0.49; low certainty evidence) which approximated to a mean creatinine clearance of 0.30 mL/min/1.73m2 higher (0.65 lower to 1.23 higher) or urine output (3 studies, 69 participants: MD -88.88 mL/d, 95% CI -356.88 to 179.12; low certainty evidence). It is uncertain whether icodextrin use led to any differences in adverse events (5 studies, 816 participants) technique failure or death.

AUTHORS' CONCLUSIONS

This updated review strengthens evidence that neutral pH, low GDP PD solution improves RRF and urine volume preservation with high certainty. These effects may be related to increased peritoneal solute transport and reduced peritoneal ultrafiltration, although the evidence for these outcomes is of low certainty due to significant heterogeneity and suboptimal methodological quality. Icodextrin prescription increased peritoneal ultrafiltration and mitigated uncontrolled fluid overload with moderate certainty. The effects of either neutral pH, low GDP solution or icodextrin on peritonitis, technique survival and patient survival remain uncertain and require further high quality, adequately powered RCTs.

"Biocompatible" Neutral pH Low-GDP Peritoneal Dialysis Solutions: Much Ado About Nothing?

Adverse outcomes in peritoneal dialysis (PD), including PD related infections, the loss of residual kidney function (RKF), and longitudinal, deleterious changes in peritoneal membrane function continue to limit the long-term success of PD therapy. The observation that these deleterious changes occur upon exposure to conventional glucose-based PD solutions fuels the search for a more biocompatible PD solution. The development of a novel PD solution with a neutral pH, and lower in glucose degradation products (GDPs) compared to its conventional predecessors has been labeled a "biocompatible" solution. While considerable evidence in support of these novel solutions' biocompatibility has emerged from cell culture and animal studies, the clinical benefits as compared to conventional PD solutions are less clear. Neutral pH low GDP (NpHLGDP) PD solutions appear to be effective in reducing infusion pain, but their effects on other clinical endpoints including peritoneal membrane function, preservation of RKF, PD-related infections, and technique and patient survival are less clear. The literature is limited by studies characterized by relatively few patients, short follow-up time, heterogeneity with regards to the novel PD solution type under study, and the different patient populations under study. Nonetheless, the search for a more biocompatible PD solution continues with emerging data on promising non glucose-based solutions.

Low GDP Solution and Glucose-Sparing Strategies for Peritoneal Dialysis

Long-term exposure to a high glucose concentration in conventional peritoneal dialysis (PD) solution has a number of direct and indirect (via glucose degradation products [GDP]) detrimental effects on the peritoneal membrane, as well as systemic metabolism. Glucose- or GDP-sparing strategies often are hypothesized to confer clinical benefits to PD patients. Icodextrin (glucose polymer) solution improves peritoneal ultrafiltration and reduces the risk of fluid overload, but these beneficial effects are probably the result of better fluid removal rather than being glucose sparing. Although frequently used for glucose sparing, the role of amino acid-based solution in this regard has not been tested thoroughly. When glucose-free solutions are used in a combination regimen, published studies showed that glycemic control was improved significantly in diabetic PD patients, and there probably are beneficial effects on peritoneal function. However, the long-term effects of glucose-free solutions, used either alone or as a combination regimen, require further studies. On the other hand, neutral pH-low GDP fluids have been shown convincingly to preserve residual renal function and urine volume. The cost effectiveness of these solutions supports the regular use of neutral pH-low GDP solutions. Nevertheless, further studies are required to determine whether neutral pH-low GDP solutions exert beneficial effects on patient-level outcomes, such as peritonitis, technique survival, and patient survival.

Complement Activation in Peritoneal Dialysis-Induced Arteriolopathy

Cardiovascular disease (CVD) is the leading cause of increased mortality in patients with CKD and is further aggravated by peritoneal dialysis (PD). Children are devoid of preexisting CVD and provide unique insight into specific uremia- and PD-induced pathomechanisms of CVD. We obtained peritoneal specimens from children with stage 5 CKD at time of PD catheter insertion (CKD5 group), children with established PD (PD group), and age-matched nonuremic controls (n=6/group). We microdissected omental arterioles from tissue layers not directly exposed to PD fluid and used adjacent sections of four arterioles per patient for transcriptomic and proteomic analyses. Findings were validated in omental and parietal arterioles from independent pediatric control (n=5), CKD5 (n=15), and PD (n=15) cohorts. Transcriptomic analysis revealed differential gene expression in control versus CKD5 arterioles and in CKD5 versus PD arterioles. Gene ontology analyses revealed activation of metabolic processes in CKD5 arterioles and of inflammatory, immunologic, and stress-response cascades in PD arterioles. PD arterioles exhibited particular upregulation of the complement system and respective regulatory pathways, with concordant findings at the proteomic level. In the validation cohorts, PD specimens had the highest abundance of omental and parietal arteriolar C1q, C3d, terminal complement complex, and phosphorylated SMAD2/3, a downstream effector of TGF-β Furthermore, in the PD parietal arterioles, C1q and terminal complement complex abundance correlated with the level of dialytic glucose exposure, abundance of phosphorylated SMAD2/3, and degree of vasculopathy. We conclude that PD fluids activate arteriolar complement and TGF-β signaling, which quantitatively correlate with the severity of arteriolar vasculopathy.

Is peritoneal dialysis causing a measurable burden of inflammatory and endothelial injury on top of metabolic syndrome?

PURPOSE

Low-grade chronic inflammation is present in patients on peritoneal dialysis (PD) and in metabolic syndrome (MS). Due to possible greater endothelial changes in dialyzed patients, inflammatory response and oxidative stress are probably stronger in patients on PD. The objective of the study was to investigate possible in between adipokines, inflammatory, endothelial and oxidative stress markers between MS patients and patients on PD.

METHODS

Concentrations of adipokines (leptin, resistin), inflammatory markers [interleukin-6 (IL-6), soluble tumor necrosis factor alpha receptor (sTNF-R), myeloperoxidase (MPO), monocyte chemoattractant protein 1 (MCP-1)] and endothelial markers [soluble intracellular adhesion molecule-1 (sICAM-1), soluble CD40 ligand (sCD40L)] were determined in 55 MS patients and 18 patients on PD, with flow cytometry, and visfatin concentration was measured with ELISA. Routine biochemistry parameters were measured on Beckman Coulter AU2700 analyzer.

RESULTS

Patients on PD have significantly higher concentration of: CRP [6.5 (3.7-12.1) versus 2.6 (1.3-4.0) mg/L, P < 0.001], IL-6 [13.83 (8.48-31.31) versus 2.05 (0.67-4.11) pg/mL, P < 0.001], MCP-1 [2172.28 (1563.84-2922.77) versus 1353.58 (1166.33-1961.70) pg/mL, P = 0.023], sTNF-R [18.25 (12.81-25.22) versus 1.23 (0.89-1.43) ng/mL, P < 0.001] and sICAM-1 [830.03 (599.21-967.02) versus 463.85 (315.25-751.71) ng/mL, P = 0.006] than subjects with MS. MS patients have higher concentrations of MPO [175.47 (120.15-231.67) versus 101.76 (53.55-186.06) ng/mL, P = 0.016] and visfatin [1.5 (0.9-2.3) versus 0.9 (0.6-1.6) ng/mL, P = 0.013].

CONCLUSION

In patients on PD, inflammatory reaction is higher than in patients with MS. On the contrary, patients with MS have stronger oxidative stress response and adipose tissue activity caused probably by the chronic low level of inflammation and underlying metabolic disorders.

The Association Between Glucose Exposure and the Risk of Peritonitis in Peritoneal Dialysis Patients

♦

BACKGROUND AND OBJECTIVE

Little or no clinical evidence is available on the association between glucose exposure and peritoneal host defense in peritoneal dialysis (PD) patients. The objective of the present study was to quantify the exposure to glucose during the first year on PD and investigate the association with subsequent peritonitis. ♦

METHODS

We analyzed prospectively collected demographic and peritonitis data from incident adult PD patients between 1990 and 2010. For the present study, we conducted a review of both in- and outpatient medical records of all patients to obtain their day-to-day dialysis schemes during the first year on PD. From these data, the average exposure to glucose was quantified. The exposure was stratified into low- and high-glucose groups based on the median, analyzed per standard deviation and in quartiles. Cox proportional hazard models were used to calculate crude and adjusted hazard ratios (HRs) and 95% confidence intervals for the association between glucose exposure and peritonitis. Adjustments were made for age, sex, primary kidney disease, diabetes mellitus, Davies comorbidity score and the treatment period. ♦

RESULTS

In total, 230 patients were included in the study of whom 151 (66%) experienced a first peritonitis episode. The median follow-up time was 2.6 years (interquartile range [IQR]: 1.9 - 3.8) in the low-glucose group and 3.1 (IQR: 2.1 - 4.2) in the high-glucose group. After adjustment for confounding factors, no association between high glucose exposure and the risk of peritonitis was found (HR: 0.81; 0.55 - 1.17). No association was present when glucose exposure was analyzed per standard deviation (SD) (HR: 0.98; 0.79 - 1.21) or patient quartiles were applied. No association was identified between glucose exposure and severe peritonitis, Staphylococcus aureus peritonitis, or a peritonitis episode that lasted more than 14 days. ♦

CONCLUSIONS

Exposure to glucose is not associated with an increased risk of peritonitis. The equilibrium between glycemic harm to peritoneal host defense and detrimental effects of glucose on invading microorganisms may determine the susceptibility to peritoneal infection.

Effect of Neutral-pH, Low-Glucose Degradation Product Peritoneal Dialysis Solutions on Residual Renal Function, Urine Volume, and Ultrafiltration: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Neutral-pH, low-glucose degradation products solutions were developed in an attempt to lessen the adverse effects of conventional peritoneal dialysis solutions. A systematic review was performed evaluating the effect of these solutions on residual renal function, urine volume, peritoneal ultrafiltration, and peritoneal small-solute transport (dialysate to plasma creatinine ratio) over time.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Multiple electronic databases were searched from January of 1995 to January of 2013. Randomized trials reporting on any of four prespecified outcomes were selected by consensus among multiple reviewers.

RESULTS

Eleven trials of 643 patients were included. Trials were generally of poor quality. The meta-analysis was performed using a random effects model. The use of neutral-pH, low-glucose degradation products solutions resulted in better preserved residual renal function at various study durations, including >1 year (combined analysis: 11 studies; 643 patients; standardized mean difference =0.17 ml/min; 95% confidence interval, 0.01 to 0.32), and greater urine volumes (eight studies; 598 patients; mean difference =128 ml/d; 95% confidence interval, 58 to 198). There was no significant difference in peritoneal ultrafiltration (seven studies; 571 patients; mean difference =-110; 95% confidence interval, -312 to 91) or dialysate to plasma creatinine ratio (six studies; 432 patients; mean difference =0.03; 95% confidence interval, 0.00 to 0.06).

CONCLUSIONS

The use of neutral-pH, low-glucose degradation products solutions results in better preservation of residual renal function and greater urine volumes. The effect on residual renal function occurred early and persisted beyond 12 months. Additional studies are required to evaluate the use of neutral-pH, low-glucose degradation products solutions on hard clinical outcomes.

Increased peritoneal permeability at peritoneal dialysis initiation is a potential cardiovascular risk in patients using biocompatible peritoneal dialysis solution

Background

Cardiovascular disease is a frequent cause of death in peritoneal dialysis patients. Biocompatible peritoneal dialysis solutions with neutral pH have been anticipated to reduce cardiovascular disease more than conventional peritoneal dialysis solutions with low pH, but it remains unclear which factors at peritoneal dialysis initiation increase cardiovascular risk in patients using biocompatible peritoneal dialysis solutions. This study was undertaken to investigate which clinical factors at peritoneal dialysis initiation, including peritoneal transport status, are associated with cardiovascular event in patients using biocompatible peritoneal dialysis solution.

Methods

This retrospective cohort study of peritoneal dialysis patients using biocompatible solutions with neutral pH assessed relations of clinical parameters at peritoneal dialysis initiation to cardiovascular event during the subsequent five years.

Results

Of 102 patients who started peritoneal dialysis, cardiovascular event occurred in 18. Age, history of cardiovascular disease before peritoneal dialysis initiation, hemoglobin, serum albumin, C-reactive protein, peritoneal permeability defined by the ratio of dialysate to plasma creatinine concentration at 4 hr (D/Pcre) in peritoneal equilibration test (PET), number of patients in each PET category defined by D/Pcre, and peritoneal protein clearance significantly differed between patients with and without cardiovascular event. For patients divided according to PET category using Kaplan–Meier method, the group of high average to high peritoneal transporters exhibited significantly high incidence of cardiovascular event and mortality compared with the groups of low and low-average peritoneal transporters (Log rank; p = 0.0003 and 0.005, respectively). A Cox proportional hazards model showed independent association of PET category classification with cardiovascular event.

Conclusions

Peritoneal permeability expressed as PET category at peritoneal dialysis initiation is an independent cardiovascular risk factor in peritoneal dialysis patients using biocompatible peritoneal dialysis solution with neutral pH. Greater peritoneal permeability at peritoneal dialysis initiation might reflect subclinical vascular disorders.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2369-15-173) contains supplementary material, which is available to authorized users.

Effect of biocompatible peritoneal dialysis solution on residual renal function: a systematic review of randomized controlled trials

INTRODUCTION

Residual renal function (RRF) plays an important role in outcome of peritoneal dialysis (PD) including mortality. It is, therefore, important to provide a strategy for the preservation of RRF. The objective of this study was to evaluate relative protective effects of new glucose-based multicompartmental PD solution (PDS), which is well known to be more biocompatible than glucose-based conventional PDS, on RRF compared to conventional PDS by performing a systematic review (SR) of randomized controlled trials.

METHODS

We searched studies presented up to January 2014 in MEDLINE, EMBASE, the COCHRANE library, and local databases. Three independent reviewers reviewed and extracted prespecified data from each study. The random effects model, a more conservative analysis model, was used to combine trials and to perform stratified analyses based on the duration of follow-up. Study quality was assessed using the Cochrane Handbook for risk of bias. Eleven articles with 1,034 patients were identified for the SR.

RESULTS

The heterogeneity of the studies under 12 months was very high, and the heterogeneity decreased substantially when we stratified studies by the duration of follow-up. The mean difference of the studies after 12 months was 0.46 mL/min/1.73 m(2) (95% confidence interval = 0.25 to + 0.67).

CONCLUSION

New PDS showed the effect to preserve and improve RRF for long-term use compared to conventional PDS, even though it did not show a significant difference to preserve RRF for short-term use.

Proteinuria as a risk factor for decline in residual renal function in non-diabetic peritoneal dialysis patients

BACKGROUND

Preservation of residual renal function (RRF) is a major issue for patients on peritoneal dialysis (PD). Whether proteinuria is associated with a decline in RRF in patients on PD remains unclear.

PATIENTS AND METHODS

We reviewed the medical records at the Yeungnam University Hospital in Korea and identified patients who started PD between June 1995 and August 2011. A total of 147 non-diabetic patients were enrolled in the study. The patients were divided into 3 groups with respect to the tertile of initial proteinuria level: Low (n = 49; <320 mg/day), Middle (n = 49; 320-822 mg/day), and High groups (n = 49; >822 mg/day).

RESULTS

The mean patient age was 50.2 ± 15.0 years in the Low tertile, 50.2 ± 15.4 years in the Middle tertile, and 49.0 ± 15.1 years in the High tertile. Decline in RRF during follow-up period was greater in the High tertile than that in the other tertiles (P = 0.001). The proportion of patients with RRF >50% of baseline at 24 months after the initiation of PD was 83% in the Low tertile, 66% in the Middle tertile, and 40% in the High tertile (P < 0.001). The multivariate analysis after adjusting for initial RRF, age, gender, underlying disease of end-stage renal disease except diabetes mellitus, PD modality, use of icodextrin, PD-associated peritonitis, and tertile of the initial proteinuria level revealed that High tertile of the initial proteinuria level was associated with a decline in RRF (hazard ratios: 2.442 for the Middle tertile, P = 0.007 ; 3.713 for the Low tertile, P < 0.001).

CONCLUSION

The present study demonstrates that proteinuria may be is associated with a rapid decline in RRF in non-diabetic patients on PD, although the potential role of additional factors should be further investigated in prospective studies.

Systemic and local impact of glucose and glucose degradation products in peritoneal dialysis solution

The main osmotic agent used in the peritoneal dialysis (PD) solution is glucose because of its great osmotic power, simple metabolism, and safety. Once into the systemic circulation, however, glucose can be a cause for metabolic complications including hyperglycemia, obesity, and dyslipidemia. The glucose absorbed from peritoneal cavity leads to insulin resistance and hyperglycemia, which is associated with oxidative stress. Long-term exposure of peritoneal membrane to glucose in PD solution also has local effects such as functional and structural changes leading to peritoneal membrane failure. Moreover, the intraperitoneal glucose absorption induces conditions similar to postprandial hyperglycemia, which is a proven independent risk factor of coronary artery disease in patients with type 2 diabetes. Though speculative, glucose toxicity might explain a higher mortality of PD patients after the first few years compared with those on hemodialysis. Glucose degradation products (GDPs) induce apoptosis of peritoneal mesothelial cells (PMCs), renal tubular epithelial cells, and endothelial cells, and facilitating epithelial mesenchymal transition of PMCs. GDPs provide a stronger reactivity than glucose in the formation of advanced glycation end-products, a known cause for microvascular complications and arteriosclerosis. Unfortunately, clinical studies using a low-GDP PD solution have provided mixed results on the residual renal function, peritonitis, peritoneal membrane function, and mortality; consistent outcome data are not readily available at present.

Biocompatible peritoneal dialysis solution preserves residual renal function

BACKGROUND/AIMS

The long-term effects of biocompatible peritoneal dialysis (PD) solution on residual renal function (RRF), inflammation, adipokines and metabolic acidosis are controversial. We evaluated the effects of biocompatible PD solution in continuous ambulatory PD (CAPD) patients for an additional 12-month period.

METHOD

Among 91 incident patients who started CAPD with either biocompatible PD solution (Balance®, Fresenius; LS, n = 48) or conventional PD solution (CAPD/DPCA®, Fresenius; CS, n = 43), 63 patients, who were followed for 12 months, were enrolled and followed for an additional 12 months.

RESULTS

After 24 months of treatment, the glomerular filtration rate (GFR) of the LS group was twofold higher compared to the CS group (33.5 ± 30.7 vs. 16.3 ± 17.9 l/week/1.73 m(2), respectively, p = 0.021). In a subgroup of patients with an initial GFR >2 ml/min/1.73 m(2), the GFR of the LS group was significantly higher than the rate of the CS group after 24 months (43.7 ± 30.5 vs. 18.6 ± 19.0 l/week/1.73 m(2), respectively, p = 0.042). Over a 24-month period, effluent cancer antigen-125 levels were significantly increased in the LS group compared to the CS group, while effluent interleukin-6 levels did not differ between the two groups. The serum tCO(2) levels were consistently higher in the LS group compared to the CS group.

CONCLUSIONS

We found that the effect of LS on preserving RRF may be maintained over a 24-month treatment period in CAPD patients, and LS use may have other benefits, such as the correction of metabolic acidosis.