Long-Term Clinical Outcomes of Peritoneal Dialysis Patients: Single Center Experience from Korea

Of a large body of literature reporting clinical outcomes for patients maintained on peritoneal dialysis (PD), most publications have focused on relatively short-term results. Few reports have focused on long-term survival in PD patients. Here, we present our experience with long-term patient outcomes and further analyses of the trends in demographics and clinical outcomes of 2301 end-stage renal disease (ESRD) patients treated with continuous ambulatory PD (CAPD) during a 25-year period (1981 – 2005) at our institute. Outcomes were analyzed for 1656 patients, excluding those younger than 15 years of age at initiation of CAPD, those having less than 3 months’ follow-up, or those who had been on hemodialysis or who received a kidney graft before starting CAPD.

In the study patients, technique survival at 5 and 10 years was 71.9% and 48.1% respectively. Patient survival was 69.8% and 51.8%. Mean age at the start of PD (50.4 ± 13.9 years vs. 44.2 ± 13.9 years, p < 0.01), ESRD incidence as a result of diabetic nephropathy (30.5% vs. 19.5%, p < 0.01), and incidence of cardiovascular comorbidities (26.6% vs. 20.5%, p < 0.01) were all significantly greater in patients who started PD during the second half of the study period (1993 – 2005) as compared with the first half (1981 – 1992). A multivariate analysis adjusting for these changes in demographics and comorbid conditions revealed that PD therapy starting in 1993 – 2005 was associated with a significant reduction in technique failure [hazard ratio (HR): 0.65; p < 0.01] and mortality (HR: 0.68; p < 0.01) as compared with the earlier period. However, in subgroup analyses, technique survival was not observed to be significantly improved in patients with diabetes.

In summary, technique and patient survival have significantly improved despite increases in patient age, cardiovascular comorbidity, and ESRD caused by diabetes. Although diabetes, older age, and cardiovascular comorbidities are not factors that are easily modifiable to improve PD outcomes, results at our institution are encouraging in an era of declining PD utilization.

Afterthoughts on colonoscopy. Was it that bad?

OBJECTIVES

Colorectal cancer is among the top three most common cancers globally. In order to reduce the health burden, it is important to improve the uptake of colorectal cancer screening by understanding the barriers and facilitators encountered. There are numerous reports in the literature on the views of the general public on cancer screening. However, the experiences of colonoscopy patients are not as well studied. This paper maps their perceptions.

METHODS

Keyword searches for terms such as 'colorectal', 'colonoscopy' and 'qualitative' were conducted on 3 December 2019 in five databases: Medline, Embase, CINAHL, PsycINFO and Web of Science Core Collection. Qualitative articles that quoted colonoscopy-experienced patients with no prior history of colorectal cancer were included for the thematic analysis. The systematic review was then synthesized according to PRISMA guidelines.

RESULTS

The major themes were distilled into three categories: pre-procedure, during and post-procedure. The factors identified in the pre-procedure phase include the troublesome bowel preparation, poor quality of information provided and the dynamics within a support network. Perceptions of pain, emotional discomfort and the role of providers mark the experience during the procedure. The receipt of results, opportunities given for discussion and finances relating to colonoscopy are important post-procedure events.

CONCLUSION

Understanding colorectal cancer screening behaviour is fundamental for healthcare providers and authorities to develop system and personal level changes for the improvement of colorectal cancer screening services. The key areas include patient comfort, the use of clearer instructional aids and graphics, establishing good patient rapport, and the availability of individualized options for sedation and the procedure.

Biocompatibility of New Peritoneal Dialysis Solutions: What Can We Hope to Achieve?

Despite the bioincompatibility of the “old”, standard, high glucose, lactate-buffered peritoneal dialysis (PD) solutions, PD is itself a highly successful dialysis modality with patient survival equivalent to that of hemodialysis (HD) during the initial 3 – 5 years of dialysis therapy. Nevertheless, PD technique survival is often limited by infectious complications and alterations in the structure and function of the peritoneal membrane. These local changes also have a negative impact on patient survival owing to systemic effects such as those often seen in patients with high peritoneal transport rate and loss of ultrafiltration (UF) capacity.

Patient mortality remains unacceptably high in both HD and PD patients, with most premature deaths being associated with signs of malnutrition, inflammation, and atherosclerotic cardiovascular disease (MIA syndrome). These systemic signs are likely to be influenced by PD solutions both directly and indirectly (via changes in the peritoneal membrane). New, biocompatible PD solutions may have favorable local effects (viability and function of the peritoneal membrane) and systemic effects (for example, on MIA syndrome). Amino acid–based solution [Nutrineal (N): Baxter Healthcare Corporation, Deerfield, IL, U.S.A.] may improve nutritional status as well as peritoneal membrane viability. Bicarbonate/lactate–buffered solution [Physioneal (P): Baxter Healthcare Corporation] may ameliorate local and systemic effects of low pH, high lactate, and high glucose degradation products. Icodextrin-based solution [Extraneal (E): Baxter Healthcare SA, Castlebar, Ireland] may improve hypertension and cardiovascular problems associated with fluid overload and may extend time on therapy in patients with loss of UF capacity.

The positive effects of each of these new, biocompatible solutions have been demonstrated in several studies. It is likely that the combined use of N, P, and E solutions will produce favorable synergies in regard to both local effects (peritoneal viability) and systemic effects (less malnutrition, inflammation, and fluid overload). Solution combination is an exciting area for clinical study in the coming years. Furthermore, dialysis fluid additives such as hyaluronan, which protects and improves the function of the peritoneal membrane, may further improve PD solutions. The new, biocompatible PD solutions represent an entirely new era in the evolution of the PD therapy; they are likely to have markedly positive effects on both PD technique and PD patient survival in coming years.

Zinc inhibits high glucose-induced NLRP3 inflammasome activation in human peritoneal mesothelial cells

Zinc (Zn) deficiency is important for inducing nucleotide-binding domain and leucine‑rich repeat‑containing family, pyrin domain-containing-3 (NLRP3) inflammasome activation in macrophages. However, its function in the NLRP3 inflammasome activation of peritoneal mesothelial cells (PMCs) remains to be elucidated. In the present study, the human PMC (HPMC) line HMrSV5 was co‑treated with high glucose and either ZnSO4 or a Zn chelator. The activity of the NLRP3/caspase‑1 inflammasome was assessed via western blot analysis, immunofluorescence, reverse transcription‑quantitative polymerase chain reaction and ELISA. In addition, the activity of the nuclear factor erythroid 2‑related factor 2 (Nrf2) pathway was detected using western blotting, and the level of reactive oxygen species (ROS) was assessed by 2,7‑dichlorofluorescein fluorescence and flow cytometry. It was found that Zn supplementation inhibited HG‑induced NLRP3 inflammasome activation in the HPMCs by attenuating ROS production. Further experiments revealed that Zn supplementation inhibited the HG‑induced production of ROS through activation of the Nrf2 antioxidant pathway. These results indicated that Zn inhibited NLRP3 inflammasome activation in the HG‑treated HPMCs by activating the Nrf2 antioxidant pathway and reducing the production of ROS.

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.

Zinc transporter 7 induced by high glucose attenuates epithelial-to-mesenchymal transition of peritoneal mesothelial cells

Zinc (Zn) is an essential micronutrient and cytoprotectant involved in preventing many types of epithelial-to-mesenchymal transition (EMT)-driven fibrosis in vivo. The zinc-transporter family SLC30A (ZnT) is a pivotal factor in the regulation of Zn homeostasis. However, its function in EMT in peritoneal mesothelial cells (PMCs) remains unknown. This study explored the regulation of zinc transporters and the role they play in cell EMT, particularly in rat peritoneal mesothelial cells (RPMCs), surrounding glucose concentrations and the molecular mechanism involved. The effects of high glucose (HG) on zinc transporter gene expression were measured in RPMCs by real-time PCR. We explored ZnT7 (Slc30A7): the effect of ZnT7 over-expression and siRNA-mediated knock-down on HG-induced EMT was investigated as well as the underlying molecular mechanisms. Over-expression of ZnT7 resulted in significantly inhibited HG-induced EMT in RPMCs, while inhibition of ZnT7 expression using a considerable siRNA-mediated knock-down of RPMCs increased the levels of EMT. Furthermore, over-expression of ZnT7 is accompanied by down-regulation of TGF-β/Smad pathway, phospho-Smad3,4 expression levels. The finding suggests that the zinc-transporting system in RPMCs is influenced by the exposure to HG. The ZnT7 may account for the inhibition of HG-induced EMT in RPMCs, likely through targeting TGF-β/Smad signaling.

Zinc supplementation attenuates high glucose-induced epithelial-to-mesenchymal transition of peritoneal mesothelial cells

Zinc (Zn) plays an important role in preventing many types of epithelial-to-mesenchymal transition (EMT)-driven fibrosis in vivo. But its function in the EMT of the peritoneal mesothelial cells (PMCs) remains unknown. Here, we studied the Zn effect on the high glucose (HG)-induced EMT in the rat PMCs (RPMCs) and the underlying molecular mechanisms. We found that Zn supplementation significantly inhibited TGF-β1 and ROS production, and attenuated the HG-induced EMT in the RPMCs, likely through inhibition of MAPK, NF-κB, and TGF-β/Smad pathways.

Comparison of icodextrin and glucose solutions for long dwell exchange in peritoneal dialysis: a meta-analysis of randomized controlled trials

BACKGROUND

Icodextrin is widely used in peritoneal dialysis (PD); however, the safety and efficacy of icodextrin are unclear. In the present study, we performed a systematic review of randomized controlled trials (RCTs) that compared icodextrin and glucose for the once-daily long dwell in PD.

METHODS

Electronic searches were performed in MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials to select all eligible studies. Eligible studies, as determined by consensus using predefined criteria, were reviewed, and data were extracted onto a standard form.

RESULTS

In the 9 RCTs that were identified, patients using icodextrin were found to have much greater net ultrafiltration (UF) and a lower incidence of negative net UF compared to patients using 1.5%, 2.5%, and 4.25% glucose solutions. Additionally, icodextrin has a markedly increased UF efficiency ratio and peritoneal clearance of creatinine and urea nitrogen, but residual renal function was not different from patients using glucose solutions for PD. No significant differences were observed between icodextrin and glucose groups with respect to risk of mortality, peritonitis, and total adverse events. Although rashes occurred significantly more often in icodextrin groups, few differences were noted between icodextrin and glucose groups when withdrawal rates secondary to adverse events were compared.

CONCLUSIONS

This meta-analysis suggests that icodextrin provides patients with greater fluid removal and small solute clearance and does not cause any damage to residual renal function. Icodextrin is particularly appropriate for use in patients with high peritoneal transport status.

Risk factors for high dialysate glucose use in PD patients--a retrospective 5-year cohort study

BACKGROUND

Use of high concentrations of glucose for peritoneal dialysis (PD) may produce unfavorable results. Our previous study showed that high initial glucose load is associated with poor PD technique survival.

OBJECTIVE

This retrospective cohort study at a medical center in Taiwan aimed to understand the factors associated with high glucose load in long-term PD patients.

PATIENTS AND METHODS

We reviewed 90 newly started PD patients over 5 years. We determined glucose load by calculating annual glucose weight and dialysate volume administered. Multiple linear regression analyses with time-dependent covariates were used to determine factors that influence the annual average dialysate glucose concentration.

RESULTS

The study group included 47 men and 43 women with a mean age of 53.4 +/- 13.9 years. Technique survival rates were 91.0%, 84.1%, and 77.6% at the beginning of the second, third, and fourth year of PD therapy respectively. The presence of diabetes mellitus (DM), high body mass index (BMI), and low weekly renal Kt/V were significantly correlated with high average dialysate glucose concentration during the first, second, and third years. For patients undergoing PD for more than 3 years, residual renal function (RRF) deteriorated, and only DM significantly affected higher dialysate glucose concentration in the fourth year.

CONCLUSIONS

Patients with DM, high BMI, and low RRF were more likely to require a high glucose load for PD therapy, especially during the first 3 years. After those 3 years of PD, DM was the only significant factor in the need for higher glucose load. To reduce the glucose load in chronic PD patients, alternative osmotic agents such as icodextrin or amino acids should be considered in the daily PD regimen.

Icodextrin: an alternative peritoneal dialysis fluid

Peritoneal dialysis is a home dialysis therapy in which a fluid known as dialysate is placed into the patient's peritoneal cavity. The standard dialysate consists of a concentrated dextrose solution. Icodextrin is a glucose polymer that can be substituted for dextrose with avoidance of some of the glucose-dependant effects. The efficacy and safety of this compound was evaluated and compared with the standard dialysate solutions. It seems to be well-tolerated overall and may offer benefits in select populations of patients with kidney failure. This seems to be especially relevant in patients with more permeable peritoneal membranes who are known as 'high-transporters'.

Icodextrin produces higher ultrafiltration in diabetic than in non-diabetic patients on continuous cyclic peritoneal dialysis

A preliminary report from our unit previously suggested that diabetic patients on continuous cyclic peritoneal dialysis (CCPD) have higher ultrafiltration (UF) with icodextrin than non-diabetic patients. To confirm this observation, we did a retrospective analysis of our patients (17 diabetic and 23 non-diabetic) who were on stable CCPD prescription using a long-day dwell with icodextrin. We collected daily UF data from these patients' records for 30 days. The two groups showed no significant difference with respect to age, gender, hemoglobin, serum albumin, peritoneal dialysis and icodextrin vintage, peritoneal membrane characteristics, CCPD prescription, and peritoneal and residual renal clearance. The overnight net UF achieved with the cycler with standard glucose dialysate was similar in the two groups (850+/-379 in diabetic vs 713+/-484 ml/day in non-diabetic, P=0.34). However, UF with icodextrin during the day dwell (14.8+/-0.8 h) was significantly higher in diabetics than non-diabetics (348+/-198 vs 137+/-311 ml/day, P=0.02). Our results show that icodextrin produces significantly higher UF in long-day dwell in diabetic ESRD patients on CCPD than in non-diabetic patients. The reason for this difference is not clear.

La biocompatibilité des solutions de dialyse péritonéale

Repeated and long-term exposure to conventional glucose-based peritoneal dialysis fluids (PDFs) with poor biocompatibility plays a central role in the pathogenesis of the functional and structural changes of the peritoneal membrane. We have used immortalized human peritoneal mesothelial cells in culture to assess in vitro the biocompatibility of PDFs. Low pH, high glucose concentration and heat sterilization represent major factors of low biocompatibility. Two recent groups of glucose derivatives have been described. Glucose degradation products (GDPs) are formed during heat sterilization (glycoxidation) and storage. GDPs can bind protein and form AGEs (Advanced Glycation End-products), which can also result from the binding of glucose to free NH2 residues of proteins (glycation). The physiological pH, and the separation of glucose during heat sterilization (low GDP content) in the most recent PDFs dramatically increase the biocompatibility. The choice of PD programs with high biocompatibility PDFs allows preserving the function of the peritoneal membrane. Improvement of PDF biocompatibility may limit the occurrence of chronic chemical peritonitis and may allow long-term PD treatment.

Recommendations for the use of icodextrin in peritoneal dialysis patients

Icodextrin is a starch-derived, high molecular weight glucose polymer, which has been shown to promote sustained ultrafiltration equivalent to that achieved with hypertonic (3.86%/4.25%) glucose exchanges during prolonged intraperitoneal dwells (up to 16 h). Patients with impaired ultrafiltration, particularly in the settings of acute peritonitis, high transporter status and diabetes mellitus, appear to derive the greatest benefit from icodextrin with respect to augmentation of dialytic fluid removal, amelioration of symptomatic fluid retention and possible prolongation of technique survival. Glycaemic control is also improved by substituting icodextrin for hypertonic glucose exchanges in diabetic patients. Preliminary in vitro and ex vivo studies suggest that icodextrin demonstrates greater peritoneal membrane biocompatibility than glucose-based dialysates, but these findings need to be confirmed by long-term clinical studies. This paper reviews the available clinical evidence pertaining to the safety and efficacy of icodextrin and makes recommendations for its use in peritonal dialysis.

In vitro biocompatibility performance of Physioneal

In vitro biocompatibility performance of Physioneal. toneal dialysis (PD) has been a successful and effective form of chronic renal replacement therapy since its introduction over 20 years ago. Despite its overall success, there is a growing body of evidence that suggests shortcomings in the preservation of membrane integrity. This has led to the development of several second-generation PD solutions that demonstrate improved biocompatibility. Physioneal, a neutral pH, bicarbonate/lactate-buffered solution, was one of the first of these new PD solutions to become commercially available. This review will focus on one of the first preclinical stages in the development of Physioneal: studies on in vitro biocompatibility testing. Studies in leukocyte, mesothelial cell, and fibroblast populations demonstrated significantly improved biocompatibility of neutral pH, bicarbonate/lactate-based solutions compared to conventional solutions. The solutions contributed to improved leukocyte viability and response to bacterial infection (e.g., phagocytosis, superoxide radical generation, and endotoxin-stimulated cytokine release). Studies on peritoneal mesothelial cells demonstrate improved cell viability, proliferation, and response to proinflammatory stimuli, and a reduced potential for angiogenesis and peritoneal fibrosis, all suggesting a better preservation of membrane structure and function. The bicarbonate/lactate-based solutions demonstrated decreased cytotoxicity and preserved cell growth in fibroblast cultures as well. In vitro biocompatibility testing has clearly demonstrated that neutral pH, bicarbonate/lactate-buffered Physioneal solutions are superior to conventional solutions in preserving cell viability and function in cell populations that contribute to peritoneal homeostasis. This positive assessment now provides a foundation and rationale for moving forward with the next stages in preclinical testing: in vivo animal models and human ex vivo studies.

Inflammation in end-stage renal disease: sources, consequences, and therapy

Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in patients with end-stage renal disease (ESRD). Although traditional risk factors are common in ESRD patients, they alone may not be sufficient to account for the high prevalence of CVD in this condition. Recent evidence demonstrates that chronic inflammation, a nontraditional risk factor which is commonly observed in ESRD patients, may cause malnutrition and progressive atherosclerotic CVD by several pathogenetic mechanisms. The causes of inflammation in ESRD are multifactorial and, while it may reflect underlying CVD, an acute-phase reaction may also be a direct cause of vascular injury by several pathogenetic mechanisms. Available data suggest that proinflammatory cytokines play a central role in the genesis of both malnutrition and CVD in ESRD. Thus it could be speculated that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) would improve survival in dialysis patients. Recent evidence has demonstrated strong associations between inflammation and both increased oxidative stress and endothelial dysfunction in ESRD patients. As there is not yet any recognized, or even proposed, treatment for ESRD patients with chronic inflammation, it would be of obvious interest to study the long-term effect of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status as well as outcome in these patients.