Peritoneal transport status correlates with morbidity but not longitudinal change of nutritional status of continuous ambulatory peritoneal dialysis patients: a 2-year prospective study

Association between protein energy wasting and peritoneal membrane transport in peritoneal dialysis

BACKGROUND

fast peritoneal transport (FT) has been associated with peritoneal albumin loss and protein energy wasting (PEW); however, this relationship has not been fully studied.

AIM

the aim of this study was to analyze the differences in nutritional parameters between fast-transport peritoneal membrane (FT-PET) and slow-transport peritoneal membrane (ST-PET), and analyze the association between FT-PET and PEW in peritoneal dialysis (PD) patients.

METHODS

a cross-sectional study of patients on PD. Peritoneal transport characteristics were assessed using the peritoneal equilibration test (PET). Malnutrition inflammation score (MIS) was used for PEW identification. Clinical and biochemical characteristics between patients with and without PEW were assessed. Association between FT-PET status and PEW were evaluated using univariate and multivariate logistic regression.

RESULTS

a total of 143 patients were included. FT-PET group showed a higher prevalence of hypoalbuminemia, edema, lower phase angle, lower energy intake, and higher values of MIS score. FT-PET was significantly associated with PEW on univariate (OR: 3.5, 95 % CI: 1.56-7.83, p = 0.002) and multivariate models (OR: 2.6, 95 % CI: 1.02-6.6, p = 0.04). This association was maintained in patients where baseline PET was performed after initiating PD therapy (OR: 6.2, 95 % CI: 1.01-38.6, p = 0.04).

CONCLUSION

FT-PET is associated with PEW evaluated by MIS score. Clinical trials to study nutritional interventions personalized to peritoneal-membrane transport characteristics should be designed.

Frailty in patients on dialysis

Frailty is a condition that is frequently observed among patients undergoing dialysis. Frailty is characterized by a decline in both physiological state and cognitive state, leading to a combination of symptoms, such as weight loss, exhaustion, low physical activity level, weakness, and slow walking speed. Frail patients not only experience a poor quality of life, but also are at higher risk of hospitalization, infection, cardiovascular events, dialysis-associated complications, and death. Frailty occurs as a result of a combination and interaction of various medical issues in patients who are on dialysis. Unfortunately, frailty has no cure. To address frailty, a multifaceted approach is necessary, involving coordinated efforts from nephrologists, geriatricians, nurses, allied health practitioners, and family members. Strategies such as optimizing nutrition and chronic kidney disease-related complications, reducing polypharmacy by deprescription, personalizing dialysis prescription, and considering home-based or assisted dialysis may help slow the decline of physical function over time in subjects with frailty. This review discusses the underlying causes of frailty in patients on dialysis and examines the methods and difficulties involved in managing frailty among this group.

Nutrition in Peritoneal Dialysis

The use of peritoneal dialysis (PD) has been associated with improved quality of life, cost-effectiveness, and better outcomes for patients with kidney failure. However, many patients utilizing PD for replacement therapy face numerous nutritional hurdles. As the use of PD continues to increase worldwide, malnutrition has become an increasingly recognized concern for patients undergoing PD. The nephrology community needs to recognize and treat malnutrition to promote optimal nutritional states for our patients. In this review, we discuss several factors that contribute to malnutrition and protein-energy wasting and explore the benefits and limitations of nutritional parameters used to assess protein-calorie malnutrition. We also emphasize updated guidelines on daily caloric, protein, and micronutrient recommendations, as well as their effects on electrolyte homeostasis.

Peritoneal Protein Loss Is Not Associated With Sarcopenia in Peritoneal Dialysis Patients

Introduction: Maintenance of a peritoneal membrane is essential for maintaining long-term peritoneal dialysis (PD). Peritoneal protein loss (PPL) is basically the loss of an essential nutrient, which may lead to malnutrition. We aimed to evaluate the association between PPL and sarcopenia in PD patients.

Methods: We conducted a cross-sectional study from September 2017 to November 2020 on all PD patients (n = 199). Finally, the patients were divided into tertiles based on the PPL level as follows: low, middle, and high. PPL (mg/day), appendicular lean mass (ALM) using dual-energy X-ray absorptiometry, and handgrip strength (HGS) were evaluated. Sarcopenia was defined using cut-off values from the Asian Working Group for Sarcopenia.

Results: The median PPL (interquartile range, interval) in the low, middle, and high tertiles were 4,229 (904, 1,706–5,111), 6,160 (760, 5,118–7,119), and 8,543 (2,284, 7,145–24,406) mg/day, respectively. HGS in the low, middle, and high tertiles was 23.4 ± 9.2, 23.8 ± 8.9, and 23.6 ± 8.3 kg, respectively (P = 0.967). The ALM index in the low, middle, and high tertiles was 6.0 ± 1.3, 6.0 ± 1.2, and 6.5 ± 1.1 kg/m², respectively (P = 0.061). Multivariate analyses did not reveal significant differences in HGS and ALM index in among tertiles. The proportions of patients with sarcopenia in the low, middle, and high tertiles was 24 (36.4%), 19 (28.4%), and 21 (31.8%), respectively (P = 0.612).

Conclusion: The present study showed that PPL is not independently associated with muscle mass, strength, and sarcopenia in PD patients.

Maximizing the Success of Peritoneal Dialysis in High Transporters

This article reviews the current understanding of high transport status in the peritoneal dialysis population and emphasizes survival can be improved for high transporters. To address the current state of knowledge on high peritoneal membrane transport, the negative impact of an increased peritoneal solute transport rate is first discussed. The potential downside of high transport status, notably on survival outcomes (as supported by registry data and meta-analysis), is highlighted. Based on recent advances and clinical studies, ways of maximizing the success of peritoneal dialysis treatment in high transporters are discussed, and management strategies are proposed.

Adequacy Targets of Peritoneal Dialysis in the Asian Population

End-stage renal disease affects a large number of patients in Asia. The percentage of patients utilizing PD varies significantly in Asian countries. Continuous ambulatory peritoneal dialysis (CAPD) accounts for about 80% of the dialysis population in Hong Kong.

In this review, we address several questions related to adequacy targets in Asians: Are Asians different? Is dialysis adequacy important for Asians? What is the magnitude of the benefit and the optimal dose of dialysis prescription? Is the adequacy target realistic?

The current international recommendations, including the Dialysis Outcomes Quality Initiative guidelines, are compared with some of our own data for Asian patients. Our published data on dialysis adequacy, nutrition, residual renal function, and peritoneal membrane transport showed that those factors have a significant impact on the morbidity and mortality of PD patients in Hong Kong.

Our results show that solute clearance as measured by Kt/V has a significant impact on the outcome of Asian CAPD patients. Although Chinese PD patients have excellent medium-term patient and technique survival despite an apparently lower Kt/V as compared with the CANUSA standard, that favorable outcome should not prevent nephrologists from providing adequate dialysis to Asian patients. From our own data and analysis, we propose a target Kt/V of 1.9 in Asian CAPD populations. Small-volume dialysis (6 L daily) may be an acceptable compromise in some Asian populations with a smaller body size, especially with residual renal function, given the financial constraints in some developing countries.

Dialysis adequacy means more than a Kt/V value; other clinical parameters are equally if not more important. Thus we should also aim at achieving adequate fluid removal and volume homeostasis, blood pressure control, good nutrition, normal acid–base balance, normal mineral metabolism, minimal anemia, and normal lipid metabolism.

Nutritional Problems of Asian Peritoneal Dialysis Patients

Clear evidence links malnutrition with poor outcome in peritoneal dialysis (PD) patients; however, most studies have evaluated Western populations, which may have clinical and demographic characteristics different from those of Asian populations. Although Asian PD patients are generally regarded to have survival superior to that of Western patients, whether that better survival is related to better nutrition in Asian patients is not clear. Past studies suggest that the overall prevalence of protein–calorie malnutrition as assessed by subjective global assessment (SGA)—especially cases of severe malnutrition—seems to be lower in Asian PD patients than in Western patients. Less activation of systemic inflammatory reaction, less comorbidity, lower prevalence of metabolic acidosis, or better compliance may be responsible for better nutritional status in Asian PD patients. Dietary protein and calorie intake, dialysis dose, and membrane transport characteristics appear not to differ significantly between Asian and non Asian PD patients. Mechanisms that explain the lower prevalence of systemic inflammatory reaction in Asian PD patients need to be investigated, along with their possible impacts on nutrition and cardiovascular morbidity and mortality. Large-scale, prospective studies are also necessary to ascertain the exact correlation between dialysis dose and nutritional status, and to determine the dietary protein and calorie intakes that maintain a positive nitrogen balance and better outcome in Asian PD patients.

Are Three Exchanges Suitable for Asian Patients on Peritoneal Dialysis?

Phenomenal growth in continuous ambulatory peritoneal dialysis (CAPD) has occurred in the developing countries of Asia. In many regions in Asia, neither governments nor insurance companies fully cover treatment expenses for dialysis. Hence, patients in developing countries such as India, Bangladesh, Pakistan, and Nepal use just three 2-L exchanges daily. Typical practice in many centers is to do daytime CAPD with a dry night. Most of our Indian patients who are on three exchanges per day showed a Kt/V of 1.67 and 2-year survival rate of 60% with a normalized protein equivalent of nitrogen appearance of 0.73 – 0.80 g/kg daily. Vegetarians had a lower protein consumption rate and lower serum albumin levels. Peritoneal membrane characteristics vary among high, high average, and low average in various regions of Asia. The prevalence of diabetic nephropathy, with its associated comorbid conditions, as a major cause of end-stage renal disease in the Indian subcontinent explains the differences in the CAPD mortality rates between India and various Asian countries. Given the financial constraints in countries in Asia, small-volume dialysis of 6 L daily may be an acceptable compromise in some patient populations with a smaller body size and significant residual renal function; however, dialysis dose should be individualized according to the needs of each patient.

Influence of Peritoneal Transport Rate, Inflammation, and Fluid Removal on Nutritional Status and Clinical Outcome in Prevalent Peritoneal Dialysis Patients

Objective

To evaluate the possible associations between peritoneal transport rate (PTR), fluid removal, inflammation, and nutritional status in patients treated with peritoneal dialysis (PD) for more than 6 months, and the impact of these factors on subsequent patient survival.

Design and Patients

A prospective study of 82 PD patients (48 males) that had been treated with PD more than 6 months. Based on the dialysate-to-plasma creatinine ratio at 4 hours of dwell (D/PCr; mean ± 1 SD), the patients were classified as having a high (H), high-average (HA), low-average (LA), or low (L) PTR.

Setting

Single PD unit in a university hospital.

Main Outcome Measures

The PTR, evaluation of adequacy of dialysis and nutritional status, and biochemical analyses were assessed at 10.8 ± 2.8 months after the start of PD.

Results

Compared to L and LA (L/LA) transporters, H and HA (H/HA) transporters had increased dialysate protein loss, glucose absorption from dialysate, and peritoneal creatinine clearance (CCr), and decreased night ultrafiltration volume and total Kt/V urea. However, nutritional variables, 24-hour total fluid removal (TFR), total CCr, and residual renal function were not significantly different between the two groups. The 24-hour TFR correlated significantly with D/PCr (rho = –0.25), mean arterial pressure (rho = –0.23), serum albumin (rho = 0.25), normalized protein equivalent of total nitrogen appearance (rho = 0.34), lean body mass (LBM) calculated from creatinine kinetics (rho = 0.41), total Kt/V urea (rho = 0.42), and total CCr (rho = 0.30). The group with serum C-reactive protein (sCRP) ⊕ 10 mg/L had a higher proportion of patients with reduced (< 1000 mL) TFR compared to the group with sCRP < 10 mg/(38% vs 16%, p = 0.04). Two-year patient survival rates from the time of the assessment were not different between the different transport groups (78% vs 73% for H/HA and L/LA, p = 0.99). Upon Cox proportional hazards multivariate analysis, age and high sCRP were independent predictors of mortality.

Conclusions

This study shows that, in a selected group of prevalent PD patients assessed after more than 6 months of PD therapy, ( 1 ) inflammation was an independent predictor for mortality; ( 2 ) reduced TFR was associated with impaired nutritional status, decreased small solute clearance, and inflammation; and ( 3 ) peritoneal transport status was not significantly associated with nutritional status and was not associated with subsequent patient survival. These results indicate that a high peritoneal solute transport rate, as such, should not be regarded as a relative contraindication for PD. Instead, the results suggest that more attention should be given to inflammation and inadequate fluid removal as predictors of mortality in PD patients.

Peritoneal Albumin Excretion is a Strong Predictor of Cardiovascular Events in Peritoneal Dialysis Patients: A Prospective Cohort Study

Background

Microalbuminuria is a marker of systemic endothelial dysfunction. We hypothesize that peritoneal albumin excretion in peritoneal dialysis (PD) patients, which is conceptually analogous to microalbuminuria in nonuremic patients, can predict cardiovascular disease in new PD patients.

Method

We studied peritoneal albumin excretion in 43 new PD patients. They were then followed prospectively for the development of cardiovascular events. All-cause mortality and duration of hospitalization for cardiovascular diseases were also recorded.

Result

The average duration of follow-up was 26.5 ± 17.6 months. During the follow-up period, 15 patients developed cardiovascular events. Event-free survival at 36 months was 81.4% and 53.6% for low (<300 mg/L) and high (≥300 mg/L) peritoneal albumin excretion groups respectively (log rank test, p = 0.042). By Cox regression analysis, the only independent factors for event-free survival were diabetic status and peritoneal albumin excretion rate. For every 100 mg/L increase in peritoneal albumin excretion, the adjusted hazard ratio of developing a cardiovascular event was 1.83 [95% confidence interval (CI) 1.11 – 3.02, p = 0.018]. Actuarial patient survival at 36 months was 85.7% and 59.1% for low and high peritoneal albumin excretion groups respectively (log rank test, p = 0.10). After adjusting for the duration of follow-up for individual patients, the average duration of hospitalization was 9.1 ± 16.2 and 21.7 ± 25.7 days per year of follow-up for low and high peritoneal albumin excretion groups respectively (Mann–Whitney U test, p = 0.012).

Conclusion

Although the sample size of our present study is small and does not have adequate statistical power, we conclude that peritoneal albumin excretion may be an important predictor of cardiovascular disease. Further studies are needed to examine the role of dialysate albumin excretion as a means of cardiovascular risk stratification in PD patients.

Peritoneal Protein Loss, Leakage or Clearance in Peritoneal Dialysis, Where do we Stand?

Peritoneal protein loss (PPL) through peritoneal effluent has been a well-recognized detrimental result of peritoneal dialysis (PD) treatment since its inception. Investigation has focused mainly on PPL quantitative and qualitative determinations and evaluation of its prognostic value.

A comprehensive review of the pathophysiology of PPL (3-pore model revisited), methods of quantification, dialysate protein composition, and impact on clinical outcomes is presented herein. The author summarizes a brief analysis of associated cardiovascular disease and nutritional consequences, exploring the controversial cause-effect on mortality and technique failure.

Therapeutic modalities aiming to reduce PPL (angiotensin-converting enzyme inhibitors [ACEI]s and vitamin D therapies) were explored, although it is unclear whether PPL represents a valid therapeutic target or, on the other hand, is solely a manifestation of endothelial dysfunction.

Duration of Hemodialysis Following Peritoneal Dialysis Cessation in Australia and New Zealand: Proposal for a Standardized Definition of Technique Failure

♦ BACKGROUND: Although technique failure is a key outcome in peritoneal dialysis (PD), there is currently no agreement on a uniform definition. We explored different definitions of PD technique failure using data from the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry. ♦ METHODS: We included 16,612 incident PD patients in Australia and New Zealand from January 1998 to December 2012. Different definitions of technique failure were applied according to the minimum number of days (30, 60, 90, 180, or 365) the patient received hemodialysis after cessation of PD. ♦ RESULTS: Median technique survival varied from 2.0 years with the 30-day definition to 2.4 years with the 365-day definition. For all definitions, the most common causes of technique failure were death, followed by infectious complications. The likelihood of a patient returning to PD within 12 months of technique failure was highest in the 30-day definition (24%), and was very small when using the 180- and 365-day definitions (3% and 0.8%, respectively). Patients whose technique failed due to mechanical reasons were the most likely to return to PD (46% within 12 months using the 30-day definition). ♦ CONCLUSIONS: Both 30- and 180-day definitions have clinical relevance but offer different perspectives with very different prognostic implications for further PD. Therefore, we propose that PD technique failure be defined by a composite endpoint of death or transfer to hemodialysis using both 30-day and 180-day definitions.

Baseline higher peritoneal transport had been associated with worse nutritional status of incident continuous ambulatory peritoneal dialysis patients in Southern China: a 1-year prospective study

The aim of the present study was to investigate the relationship between baseline peritoneal transport types and nutritional status in Chinese continuous ambulatory peritoneal dialysis (CAPD) patients. In the present single-centre, prospective study, incident CAPD patients were included from 15 April 2010 to 31 December 2011 and were followed up for 12 months. According to the results of baseline peritoneal equilibration test, patients were divided into lower peritoneal transport group (lower transporters) and higher peritoneal transport group (higher transporters). Nutritional status was evaluated by both subjective global assessment (SGA) and protein-energy wasting (PEW) score. The body composition parameters were assessed by body impedance analysis. A total of 283 CAPD patients were included in the study, of which 171 (60.4 %) were males with a mean age of 47.0 (sd 14.9) years. Compared with lower transporters (n 92), higher transporters (n 181) had lower levels of serum albumin (37.1 (sd 4.3) v. 39.6 (sd 4.3) g/l, P< 0.001), serum pre-albumin (356 (sd 99) v. 384 (sd 90) mg/l, P= 0.035), phase angle (6.15 (sd 0.39) v. 6.27 (sd 0.47)°, P< 0.05) and higher rate of malnutrition defined by SGA (52.5 v. 25.0%, P< 0.001) and PEW score (37.0 v. 14.1 %, P< 0.001) at 1-year of follow-up. Baseline higher peritoneal transport, analysed by multivariate binary logistic regressions, was independently associated with malnutrition (SGA mild to moderate and severe malnutrition: OR 3.43, 95% CI 1.69, 6.96, P< 0.01; PEW: OR 2.40, 95% CI 1.08, 5.31, P= 0.03). It was concluded that baseline higher peritoneal transport was independently associated with worse nutritional status of CAPD patients in Southern China.

Peritoneal Equilibration Test and Patient Outcomes

BACKGROUND AND OBJECTIVES

Although a peritoneal equilibration test yields data on three parameters (4-hour dialysate/plasma creatinine, 4- to 0-hour dialysate glucose, and 4-hour ultrafiltration volume), all studies have focused on the prognostic value of dialysate/plasma creatinine for patients undergoing peritoneal dialysis. Because dialysate 4- to 0-hour glucose and ultrafiltration volume may be superior in predicting daily ultrafiltration, the likely mechanism for the association of peritoneal equilibration test results with outcomes, we hypothesized that they are superior to dialysate/plasma creatinine for risk prediction.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We examined unadjusted and adjusted associations of three peritoneal equilibration test parameters with all-cause mortality, technique failure, and hospitalization rate in 10,142 patients on peritoneal dialysis treated between January 1, 2007 and December 31, 2011 in 764 dialysis facilities operated by a single large dialysis organization in the United States, with a median follow-up period of 15.8 months; 87% were treated with automated peritoneal dialysis.

RESULTS

Demographic and clinical parameters explained only 8% of the variability in dialysate/plasma creatinine. There was a linear association between dialysate/plasma creatinine and mortality (adjusted hazards ratio per 0.1 unit higher, 1.07; 95% confidence interval, 1.02 to 1.13) and hospitalization rate (adjusted incidence rate ratio per 0.1 unit higher, 1.05; 95% confidence interval, 1.03 to 1.06). Dialysate/plasma creatinine and dialysate glucose were highly correlated (r=-0.84) and yielded similar risk prediction. Ultrafiltration volume was inversely related with hospitalization rate but not with all-cause mortality. None of the parameters were associated with technique failure. Adding 4- to 0-hour dialysate glucose, ultrafiltration volume, or both did not result in any improvement in risk prediction with dialysate/plasma creatinine alone.

CONCLUSIONS

This analysis from a large contemporary cohort treated primarily with automated peritoneal dialysis validates dialysate/plasma creatinine as a robust predictor of outcomes in patients treated with peritoneal dialysis.

Clinical outcomes and mortality in elderly peritoneal dialysis patients

OBJECTIVES

To evaluate the clinical outcomes and identify the predictors of mortality in elderly patients undergoing peritoneal dialysis.

METHODS

We conducted a retrospective study including all incident peritoneal dialysis cases in patients ≥65 years of age treated from 2001 to 2014. Demographic and clinical data on the initiation of peritoneal dialysis and the clinical events during the study period were collected. Infectious complications were recorded. Overall and technique survival rates were analyzed.

RESULTS

Fifty-eight patients who began peritoneal dialysis during the study period were considered for analysis, and 50 of these patients were included in the final analysis. Peritoneal dialysis exchanges were performed by another person for 65% of the patients, whereas 79.9% of patients preferred to perform the peritoneal dialysis themselves. Peritonitis and catheter exit site/tunnel infection incidences were 20.4±16.3 and 24.6±17.4 patient-months, respectively. During the follow-up period, 40 patients were withdrawn from peritoneal dialysis. Causes of death included peritonitis and/or sepsis (50%) and cardiovascular events (30%). The mean patient survival time was 38.9±4.3 months, and the survival rates were 78.8%, 66.8%, 50.9% and 19.5% at 1, 2, 3 and 4 years after peritoneal dialysis initiation, respectively. Advanced age, the presence of additional diseases, increased episodes of peritonitis, the use of continuous ambulatory peritoneal dialysis, and low albumin levels and daily urine volumes (<100 ml) at the initiation of peritoneal dialysis were predictors of mortality. The mean technique survival duration was 61.7±5.2 months. The technique survival rates were 97.9%, 90.6%, 81.5% and 71% at 1, 2, 3 and 4 years, respectively. None of the factors analyzed were predictors of technique survival.

CONCLUSIONS

Mortality was higher in elderly patients. Factors affecting mortality in elderly patients included advanced age, the presence of comorbid diseases, increased episodes of peritonitis, use of continuous ambulatory peritoneal dialysis, and low albumin levels and daily urine volumes (<100 ml) at the initiation of peritoneal dialysis.

High peritoneal transport status was not associated with mortality in peritoneal dialysis patients with diabetes

BACKGROUND

Continuous ambulatory peritoneal dialysis (CAPD) patients with diabetes are at increased risk of mortality and high peritoneal transporters appear to contribute to poor survival. However, little is known about the combined impacts of high peritoneal transporters and diabetes on mortality.

METHODS

This was a prospective observational cohort study. 776 incident CAPD patients were enrolled. Unadjusted and adjusted Cox proportional regression models were used to evaluate the association and interaction of peritoneal transport and diabetic status with mortality.

RESULTS

In the entire cohort, high peritoneal transport status was associated with an increased risk of all-cause mortality in unadjusted model [hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.30 to 4.25, P = 0.01], but this association was not significant in multivariable model. There was an interaction between peritoneal membrane transport status and diabetes (P = 0.028). Subgroup analyses showed that compared to low and low average transporters, high transporters was associated with a higher risk of all-cause mortality (adjusted HR 1.78, 95% CI 1.07 to 4.70, P = 0.04) in CAPD patients without diabetes, but not in those with diabetes (adjusted HR 0.79, 95%CI 0.33 to 1.89, P = 0.59). Results were similar when transport status was assessed as a continuous variable.

CONCLUSIONS

The association between high peritoneal transport and all-cause mortality was likely to vary with diabetes status. High peritoneal transport was associated with an elevated risk of death among CAPD patients without diabetes, but not in those with diabetes.

Inflammatory factors for hypoalbuminemia in Japanese peritoneal dialysis patients

AIM

Hypoalbuminaemia is a common complication of peritoneal dialysis (PD), and the leakage of albumin through peritoneal membrane may be a principal reason for hypoalbuminaemia. However, the relationship between peritoneal inflammation, peritoneal transport properties and hypoalbuminaemia has not been fully elucidated.

METHODS

A cross-sectional study was performed on 76 Japanese PD patients who had been using a low-glucose PD solution and icodextrin. Systemic inflammatory markers of C-reactive protein (CRP) and serum interleukin-6 (IL-6), peritoneal effluent markers of dialysate IL-6 and CA125, the dialysate-to-plasma ratio of creatinine (D/Pcr) and the dialysate protein concentration were measured and examined for their relationship with hypoalbuminaemia.

RESULTS

There was a significant positive correlation between serum IL-6 and dialysate IL-6, mean dialysate IL-6 being significantly higher than mean serum IL-6, suggesting that intraperitoneal inflammation was a principal origin of systemic inflammation. Both serum and dialysate IL-6 were significantly correlated with serum albumin (r= -0.25, P<0.05 and r=-0.32, P<0.01, respectively). Dialysate IL-6 was significantly correlated with D/Pcr and the dialysate protein concentration, and there was a significantly positive association between D/Pcr and the dialysate protein concentration. Dialysate CA125, which is argued to be a marker of mesothelial cell mass in this study, was positively correlated with D/Pcr and the dialysate protein concentration. The dialysate protein, dialysate IL-6 and dialysate CA125 all increased according to the peritoneal transport rate defined by D/Pcr. A multiple-regression analysis showed that serum albumin was independently associated with the age, D/Pcr and serum IL-6.

CONCLUSION

Hypoalbuminaemia was attributable to both the increased peritoneal permeability and systemic inflammation, and intraperitoneal inflammation might contribute to developing these complications.

Peritoneal changes in patients on long-term peritoneal dialysis

Long-term peritoneal dialysis can lead to morphological and functional changes in the peritoneum. Although the range of morphological alterations is known for the peritoneal dialysis population as a whole, these changes will not occur in every patient in the same sequence and to the same extent. Longitudinal studies are therefore required to help identify which patients might develop the changes. Although longitudinal studies using peritoneal biopsies are not possible, analyses of peritoneal effluent biomarkers that represent morphological alterations could provide insight. Longitudinal studies on peritoneal transport have been performed, but follow-up has often been too short and an insufficient number of parameters have been investigated. This Review will firstly describe peritoneal morphology and structure and will then focus on peritoneal effluent biomarkers and their changes over time. Net ultrafiltration will also be discussed together with the transport of small solutes. Data on the peritoneal transport of serum proteins show that serum protein levels do not increase to the same extent as levels of small solutes with long-term peritoneal dialysis. Early alterations in peritoneal transport must be distinguished from alterations that only develop with long-term peritoneal dialysis. Early alterations are related to vasoactive mediators, whereas later alterations are related to neoangiogenesis and fibrosis. Modern peritoneal dialysis should focus on the early detection of long-term membrane alterations by biomarkers--such as cancer antigen 125, interleukin-6 and plasminogen activator inhibitor 1--and the improved assessment of peritoneal transport.

Nutrition and the kidney: recommendations for peritoneal dialysis

Protein energy wasting (PEW) is highly prevalent in peritoneal dialysis (PD) and is associated with poor outcomes, including hospitalization and mortality. Recognizing and diagnosing PEW in PD is important; although studies are limited, there are interventions that may be associated with improved outcomes. In this review of nutritional aspects of PD, we highlight some of the important causes of PEW and explore the current diagnostic tools that are used to assess PEW. Finally, we discuss the established and experimental therapies for PEW in PD.

Nutrition in patients on peritoneal dialysis

Protein-energy wasting (PEW) is prevalent among patients on dialysis and has emerged as an important risk factor for morbidity and mortality in these patients. Numerous factors, including inflammation, inadequate dialysis, insufficient nutrient intake, loss of protein during dialysis, chronic acidosis, hypercatabolic illness and comorbid conditions, are involved in the development of PEW. The causes and clinical features of PEW in patients on peritoneal dialysis and hemodialysis are comparable; assessment of the factors that lead to PEW in patients receiving peritoneal dialysis is important to ensure that PEW is managed correctly in these patients. For the past 20 years, much progress has been made in the prevention and treatment of PEW. However, the results of most nutritional intervention studies are inconclusive. In addition, the multifactorial and complicated pathogenesis of PEW makes it difficult to assess and treat. This Review summarizes the nutritional issues regarding the causes, assessment and treatment of PEW, with a focus on patients receiving peritoneal dialysis. In addition, an in-depth overview of the results of nutritional intervention studies is provided.

High peritoneal transport status is not an independent risk factor for high mortality in patients treated with automated peritoneal dialysis

We undertook this study to elucidate whether baseline peritoneal membrane transport characteristics are associated with high mortality in incident automated peritoneal dialysis (APD) patients. This retrospective study includes 117 patients who started APD at Yonsei University Health System from 1996 to 2008 and had a PET within 3 months of APD initiation. High transporters were significantly older and had a higher incidence of cardiovascular disease. Patient survival for years 1, 3, and 5 were 85%, 64%, and 35% for high transporter and 94%, 81%, and 68% for non-high transporter group (P<0.01). Multivariate analysis revealed that age, diabetes, cardiovascular disease, serum albumin level, and residual renal function were independently associated with high mortality in APD patients. In contrast, high transport status was not a significant predictor for mortality in this population when the other covariates were included. Even though high transport was significantly associated with mortality in the univariate analysis, its role seemed to be influenced by other comorbid conditions. These findings suggest that the proper management of these comorbid conditions, as well as appropriate ultrafiltration by use of APD and/or icodextrin, must be considered as protective strategies to improve survival in peritoneal dialysis patients with high transport.

Endotoxemia is associated with better clinical outcome in incident Chinese peritoneal dialysis patients: a prospective cohort study

BACKGROUND

Endotoxemia is common in peritoneal dialysis (PD) patients; circulating lipopolysaccharide (LPS) level is related to the degree of systemic inflammation and atherosclerosis. We examine whether baseline plasma LPS level represents a prognostic marker in new PD patients.

METHODS

We studied 158 new Chinese PD patients (80 males). Baseline plasma LPS level at initiation of PD was measured. Patients were stratified into quartiles according to plasma LPS level: quartile I, <0.45 EU/mL; II, 0.45 - <0.70 EU/mL; III, 0.70 - <0.95 EU/mL; and IV, ≥ 0.95 EU/mL. The patients were then prospectively followed for the development of cardiovascular events. All-cause mortality and duration of hospitalization were also recorded.

RESULTS

Average age was 55.6 +/- 14.7 years; average endotoxin concentration was 0.70 +/- 0.30 EU/mL; average follow-up was 55.5 +/- 36.9 months. At 60 months, event-free survival was 41.0%, 52.5%, 65.0%, and 61.5% for LPS level quartiles I, II, III, and IV, respectively (log rank test p = 0.066). By multivariate analysis with the Cox proportional hazard model to adjust for confounders, plasma LPS level had no independent effect. At 60 months, technique survival was 20.5%, 20.0%, 32.5%, and 51.3% for LPS level quartiles I, II, III, and IV, respectively (log rank test p = 0.0009). By Cox proportional hazard model, each higher quartile of LPS conferred 28.6% protection (95% confidence interval 15.6% - 40.3%, p = 0.0002) from developing technique failure. A higher plasma LPS level had a lower all-cause mortality (unadjusted hazard ratio 0.486, p = 0.046) and cardiovascular mortality (unadjusted hazard ratio 0.251, p = 0.025), but the result became insignificant after adjusting for potential confounders.

CONCLUSION

A higher baseline plasma LPS level is an independent predictor of better technique survival in new Chinese PD patients, with an insignificant trend of fewer cardiovascular events. The observation seems to conform to the phenomenon of reverse epidemiology for other traditional cardiovascular risk factors in dialysis patients but the exact reason for this paradoxical phenomenon requires further investigation.

Mitigating peritoneal membrane characteristics in modern peritoneal dialysis therapy

Membrane function at the start of peritoneal dialysis (PD) treatment, measured as solute transport rate and ultrafiltration capacity, varies considerably between individuals. Although this can be correlated to clinical factors such as age and body habitus, this accounts for little of the variance seen. It is increasingly clear, however, that this variability in membrane function does impact on clinical outcomes. Specifically, high solute transport increases mortality risk, independent of other known factors such as age, comorbidity, and residual renal function. High solute transport causes earlier loss of the osmotic gradient when a low molecular weight osmolyte such as glucose is used. This will result in an earlier and lower peak in the ultrafiltration achieved combined with a higher fluid absorption rate once the osmotic gradient is lost. It is therefore quite plausible that the worse clinical outcomes associated with high transport reflect less good ultrafiltration, although other explanations must be considered, including higher peritoneal protein losses and a possible association with systemic inflammation. Strategies now exist to mitigate the effects of high transport on fluid removal. These include optimization of the short dwell lengths using automated PD (APD) combined with icodextrin which will result in sustained ultrafiltration and thus prevention of reabsorption in the long dwell. Survival analysis of APD patients, especially in cohorts in which icodextrin has been used, would suggest that high transport status is not a risk factor, although some of these data are only preliminary. In contrast, low ultrafiltration capacity of the membrane seems to be more important in these patients, especially if anuric. Here the best strategy would seem to be prevention as patients who develop low ultrafiltration capacity are not easily treated on PD. Avoiding excessive hypertonic glucose exposure and preserving residual renal function offers the best available approach.

Evaluation of peritoneal transport and membrane status in peritoneal dialysis: focus on incident fast transporters

BACKGROUND/AIM

The determinants of baseline fast solute transport are still unclear. We prospectively investigated the relationship of peritoneal solute transport with markers of inflammation, angiogenesis, and membrane status, with a focus on fast transporters.

METHODS

Seventy-one incident peritoneal dialysis patients were assessed with baseline and annual peritoneal equilibration tests, using a 3.86% glucose dialysis solution. Residual renal function and markers of inflammation, including systemic and intraperitoneal interleukin-6 (IL-6), effluent cancer antigen 125 (CA-125), and vascular endothelial growth factor (VEGF) appearance rates (ARs), were investigated. The time course of the dialysate-to-plasma ratio of creatinine (D/P creatinine ratio) and its relationship with the biomarkers were investigated by a mixed linear model.

RESULTS

Incident fast/fast average transporters had a similar age, diabetes prevalence, and serum and effluent IL-6 levels, but significantly higher levels of CA-125 and VEGF ARs than the slow/slow average group; the D/P creatinine ratio was not correlated with systemic IL-6, but was correlated with effluent CA-125 AR (r = 0.45, p < 0.0001) and VEGF AR (r = 0.52, p < 0.0001). The D/P creatinine ratio decreased with a U-shaped profile (p = 0.02). Intraperitoneal IL-6 was the significant and positive determinant of the time course of the D/P creatinine ratio (p < 0.0001). Effluent CA-125 decreased with time on peritoneal dialysis (p = 0.013).

CONCLUSIONS

Baseline peritoneal fast transport was not associated with systemic inflammation, but was related to peritoneal locally produced substances able to mediate transitory hyperpermeability. The D/P creatinine ratio changed during the follow-up period with a U-shaped profile. This was associated with effluent IL-6 and partly with VEGF. CA-125 decreased throughout the follow-up period.

Meta-Analysis: Peritoneal Membrane Transport, Mortality, and Technique Failure in Peritoneal Dialysis

Peritoneal membrane solute transport in peritoneal dialysis (PD) patients is assessed by the peritoneal equilibration test, which measures the ratio of creatinine in the dialysate to plasma after a standardized 4-h dwell (D/Pc). Patients then are classified as high, high-average, low-average, or low transporters on the basis of this result. A meta-analysis of observational studies was carried out to characterize the relationship between D/Pc and mortality and technique failure in patients who are on PD. Citations were identified in Medline by using a combination of Medical Subject Heading search terms and key words related to PD, peritoneal membrane permeability/transport, and mortality and technique failure. The table of contents of relevant journals and bibliographies of relevant citations were reviewed in duplicate. Twenty studies that met study criteria were identified. Nineteen studies were pooled to generate a summary mortality relative risk of 1.15 for every 0.1 increase in the D/Pc (95% confidence interval 1.07 to 1.23; P < 001). This result equated to an increased mortality risk of 21.9, 45.7, and 77.3% in low-average, high-average, and high transporters, respectively, as compared with patients with low transport status. Meta-regression analysis showed that the proportion of patients who were on continuous cycler PD within a study was inversely proportional to the mortality risk (P = 0.05). The pooled summary relative risk for death-censored technique failure was 1.18 (95% confidence interval 0.96 to 1.46; P = 0.12) for every 0.1 increase in the D/Pc. This meta-analysis demonstrates that a higher peritoneal membrane solute transport rate is associated with a higher mortality risk and a trend to higher technique failure.

Relationship of ENOS and RAS Gene Polymorphisms to Initial Peritoneal Transport Status in Peritoneal Dialysis Patients

BACKGROUND

Peritoneal membrane permeability is of major importance for adequate dialysis and fluid balance in peritoneal dialysis (PD) therapy. The peritoneal capillary endothelium plays a key role in peritoneal transport. Nitric oxide derived from endothelial cells is related to the maintenance of vascular permeability. We investigated the relationship between the endothelial nitric oxide synthase (ENOS) gene polymorphism, the renin-angiotensin system (RAS) gene polymorphisms, and initial peritoneal transport type in PD patients.

METHODS

This study included 74 incident continuous ambulatory PD patients. The ENOS gene polymorphism was identified at the 4a/b variable number of tandem repeats in intron 4. Genetic polymorphisms of the renin-angiotensin system were performed for the angiotensin-converting enzyme I/D, angiotensinogen M235T, and angiotensin II type 1 receptor A1166C and type 2 receptor C3123A by polymerase chain reaction. Patients were divided into two groups according to the initial peritoneal equilibration test results performed within 3 months of PD therapy: group 1 consisted of high/high average transporters (n = 41), and group 2 consisted of low/low average transporters (n = 33).

RESULTS

Demographic, clinical, and laboratory data were similar between the two groups (p > 0.05). Group 1 had a significantly higher prevalence of the ENOS b/b genotype than group 2 (78% vs. 48.5%, p < 0.008). In contrast, group 2 had a significantly greater prevalence of the ENOS a/a+a/b genotype than group 1 (51.5% vs. 22%, p < 0.008). Genetic polymorphisms of the renin-angiotensin system were not associated with initial peritoneal transport type (p > 0.05).

CONCLUSIONS

Modulation of the nitric oxide activity via the ENOS a/b polymorphism may have a considerable effect on the basal peritoneal permeability.

Apparent successful mesothelial cell transplantation hampered by peritoneal activation

BACKGROUND

Mesothelial cell transplantation has been suggested to improve mesothelial repair after surgery, recurrent peritonitis and peritoneal dialysis.

METHODS

In this study we evaluated mesothelial cell transplantation during the resolution phase of experimentally thioglycollate-induced peritonitis in rats. To this end 4 x 10(6) DiO-labeled autologous mesothelial cells were transplanted 1 week after peritonitis induction. Peritoneal inflammation and permeability characteristics were evaluated after another week.

RESULTS

Mesothelial cell transplantation after peritonitis resulted in incorporation of these cells in the parietal mesothelial lining, leading to an acute transient submesothelial thickening which was not seen in transplanted animals without prior peritonitis induction. Long-term functioning of these repopulated mesothelial cells leaded to peritoneal activation as evidenced by a approximately twofold increase in peritoneal lymphocytes (P < 0.01) and omental mast cell counts (P < 0.05), accompanied by the induction of inflammation markers monocyte chemoattractant protein-1 (MCP-1) (P < 0.01) and hyaluronan (P < 0.01) in the transplanted peritonitis group, but not in rats with peritonitis without mesothelial cell transplantation or in control rats without mesothelial cell transplantation (all four parameters P < 0.01). In addition, trapping of transplanted mesothelial cells in the milky spots of omental tissue and lymphatic stomata of the diaphragm both in control and thioglycollate rats seems to increase microvascular permeability, reflected by apparent increased diffusion rates of small solutes and proteins.

CONCLUSION

Altogether, our data underscore the importance of controlling peritoneal (patho)physiology and function in mesothelial transplantation protocols.

The personal dialysis capacity test is superior to the peritoneal equilibration test to discriminate inflammation as the cause of fast transport status in peritoneal dialysis patients

This study evaluated the potential of the Personal Dialysis Capacity (PDC) test to discriminate fast transport status (FTS) as a consequence of inflammation versus FTS because of other causes. This distinction is important because new therapeutic options such as icodextrin and automated peritoneal dialysis can abolish the negative impact on outcome of FTS if fast transport is not caused by inflammation. A PDC test and a Peritoneal Equilibration Test (PET) were performed in 135 incident PD patients. Membrane characteristics were related with baseline biochemical parameters and C-reactive protein. After correction for other covariates, only large pore flux (J(v)L) but not surface area over diffusion distance (A0/dX) or dialysate over plasma concentration was related to C-reactive protein. Using the PDC test for detection of inflammation, positive and negative predictive values were 16/36 and 80/99, respectively, whereas with PET, positive predictive value was 5/20 and negative predictive value 92/115 (chi2 = 0.009). In a Cox regression for patient survival with correction for age, a J(v)L higher than expected by the surface area over diffusion distance, predicted outcome (P = 0.04). Patients with inflammation had a higher J(v)L (0.21 +/- 0.12 versus 0.17 +/- 0.09; P = 0.06) and a lower ultrafiltration (89 +/- 631 versus 386 +/- 601 ml/d; P = 0.06) and urine output (878.45 +/- 533.55 versus 1322 +/- 822 ml/d; P = 0.023) than patients without inflammation. There was no difference for surface area over diffusion distance (A0/dX) or dialysate over plasma concentration. A PDC test yields far more information about the peritoneal membrane characteristics than a PET. A J(v)L higher than expected by the A0/dX is an indicator of inflammation and is related to an increased mortality. The PET is not able to discriminate between FTS because of inflammation versus because of anatomic reasons, whereas the PDC test does.

Peritoneal fast transport in incident peritoneal dialysis patients is not consistently associated with systemic inflammation

BACKGROUND

The determinants of peritoneal fast transport status at the beginning of peritoneal dialysis (PD) are still under debate. The relationship between fast transport status and inflammation or co-morbidity, and its impact on patient survival are not fully elucidated. Our objective was to investigate if fast transport status in incident patients is associated with markers of inflammation and atherosclerosis, and its relationship to patient survival.

METHODS

Seventy-three incident patients on PD performed a 3.86% peritoneal equilibrium test (PET) at 4.7+/-2.7 months after starting PD. Doppler carotid wall intima-media thickness (IMT) and the presence of carotid plaque were used as markers of atherosclerosis. C-reactive protein (CRP) and serum interleukin-6 (IL-6) were evaluated as markers of systemic inflammation. Baseline plasma levels of albumin, homocysteine, lipoprotein (a) [Lp(a)] and other lipid parameters were measured. Body mass index and residual renal function (RRF) were calculated. Patients were classified with the Davies co-morbidity score.

RESULTS

The dialysate-plasma creatinine ratio (D/P creatinine) was 0.75 +/- 0.10; 26% were fast transporters (D/P > or = 0.85). In comparison with other transport categories, these had similar age, body mass index and RRF, and did not present a higher co-morbidity score than non-fast transporters. IMT did not significantly differ between groups. By multiple regression analysis, baseline peritoneal small solute transport was not related to systemic inflammation biomarkers. Fast transporters did not present higher levels of CRP or serum IL-6. Plasma levels of lipids, Lp(a), calcium x phosphorus product and albumin also did not differ between groups. Similar results were obtained when patients were grouped according to mass transfer area coefficient for creatinine. Patients with more than two co-morbidities had lower levels of plasma albumin (3.6 +/- 0.58 vs 3.9 +/- 0.9 g/dl, P = 0.054), significantly higher median levels of serum IL-6 (19.3 vs 9.2 pg/ml, P = 0.003) and wider IMT (0.90 +/- 0.36 vs 0.65 +/- 0.28 mm, P = 0.017). Multivariate analysis confirmed that baseline peritoneal transport was not a significant determinant of patient survival (P = 0.848), while the co-morbidity score remained significant (hazard ratio = 3.48, 95% confidence interval = 1.29-9.38, P = 0.014).

CONCLUSION

Initial fast transport was not associated with systemic inflammation and atherosclerosis. In a population with preserved RRF and absence of baseline serious co-morbidity, it was not predictive of worse prognosis. Other determinants of early peritoneal fast transport deserve investigation.

Genetic polymorphism of VEGF: Impact on longitudinal change of peritoneal transport and survival of peritoneal dialysis patients

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a pivotal role in the peritoneal angiogenesis and hyperpermeability in patients on peritoneal dialysis. We hypothesis that VEGF genetic polymorphism may affect the longitudinal change of peritoneal transport and clinical outcome of peritoneal dialysis patients.

METHODS

We studied 135 consecutive new peritoneal dialysis patients. VEGF genetic polymorphism at -1154 and -2578 positions were determined by polymerase chain reaction (PCR) methodologies. Standard peritoneal test and dialysis adequacy and transport test (DATT) were performed at the initiation of peritoneal dialysis. After 12 months, DATT was repeated in 83 patients. In 35 patients, VEGF production in vivo was determined by its levels in serum and peritoneal dialysis effluent, and mRNA expression in peritoneal dialysis effluent. Patients were followed for 19.4 +/- 8.5 months for survival study.

RESULTS

There was no relation between VEGF genotype and baseline peritoneal transport group. The changes in 24-hour dialysate-to-plasma (D/P) creatinine after 12 months were 0.028 +/- 0.159, -0.013 +/- 0.137, and 0.141 +/- 0.231 for CC, CA, and AA genotype at -2578 position, respectively [one-way analysis of variance (ANOVA), P= 0.028]. The AA genotype had significantly higher increase in 24-hour D/P creatinine than the other genotypes. Similar results were found with the genotype at -1154 position, which had marked linkage disequilibrium with the genotype at -2578 position. Actuarial patient survival was 90.3% and 74.9% at 24 months for CC and CA/AA genotypes at -2578 position, respectively (P= 0.036). After correcting for confounding covariates, the adjusted hazard ratio of death was 3.04 (95% CI, 1.10 to 8.36) for the CA/AA group as compared to CC group. Although baseline serum VEGF level was higher in patients with CC genotype than those with CA/AA genotype at -2578 position (541.5 +/- 322.8 pg/mL vs. 298.8 +/- 209.4 pg/mL, P= 0.012), VEGF mRNA expression in peritoneal dialysis effluent was significantly lower in patients with CC genotype (1.82 +/- 2.77 vs 4.48 +/- 3.28, P= 0.021). VEGF protein level in peritoneal dialysis effluent was also marginally lower in patients with CC genotype, although the difference was not significant. Genotype at -1154 position was not associated with VEGF production in vivo or patient survival.

CONCLUSION

We conclude that in peritoneal dialysis patients, the AA genotype of VEGF promoter at -2578 position was associated with progressive increase in peritoneal transport. The CA/AA genotype at -2578 position was also associated with an excess mortality. Our finding also suggests that systemic and local peritoneal VEGF production may be differentially regulated.

Predictors of baseline peritoneal transport status in Australian and New Zealand peritoneal dialysis patients

BACKGROUND

Factors that predict peritoneal transport status in peritoneal dialysis (PD) patients are poorly understood. The aim of the present study is to determine these factors in Australian and New Zealand incident PD patients.

METHODS

The study included all patients on the Australian and New Zealand Dialysis and Transplant Registry who started PD therapy between April 1, 1991, and March 31, 2002, and underwent a peritoneal equilibration test (PET) within the first 6 months. Predictors of peritoneal transport category and dialysate-plasma creatinine ratio at 4 hours (D-P Cr 4h) were assessed by multivariate ordinal logistic regression and multiple linear regression, respectively.

RESULTS

A total of 3,188 patients were studied. Mean D-P Cr 4h was 0.69 +/- 0.13. High transport status was associated with older age (adjusted odds ratio [OR], 1.08 for each 10 years; 95% confidence interval [CI], 1.03 to 1.13), Maori and Pacific Islander racial origin (OR, 1.48; 95% CI, 1.13 to 1.94), and normal body mass index (BMI; < 18.5 kg/m2: OR, 0.90; 95% CI, 0.65 to 1.24; BMI of 18.5 to 25 kg/m2: OR, 1 [reference]; BMI of 25 to 30 kg/m2: OR, 0.81; 95% CI, 0.70 to 0.95; BMI > 30 kg/m2: OR, 0.71; 95% CI, 0.58 to 0.86), but was not independently predicted by sex, diabetes, other comorbid diseases, smoking, previous hemodialysis therapy or transplantation, or residual renal function. Similar results were found when peritoneal permeability was modeled as a continuous variable (D-P Cr 4h).

CONCLUSION

In Australian and New Zealand PD patients, higher peritoneal transport status is independently associated with racial origin, older age, and lower BMI. The diversity of peritoneal transport characteristics in different ethnic populations suggests that additional validation of PET measurements in various racial groups and study of their relationship to patient outcomes are warranted.

A 3-year, prospective, randomized, controlled study on amino acid dialysate in patients on CAPD

BACKGROUND

Malnutrition is prevalent in patients on continuous ambulatory peritoneal dialysis (CAPD) and confers a poor prognosis. Inadequate nutrient intake is an important contributing factor. Although short-term studies have shown mild to modest nutritional benefit with amino acid dialysate, its long-term effects and tolerability remain obscure.

METHODS

The authors have performed a 3-year, randomized, prospective, controlled study of amino acid dialysate in malnourished Chinese patients on CAPD. Sixty patients were assigned randomly to either replace 1 exchange daily with amino acid dialysate (Nutrineal; DAA group, n = 30) or to continue with dextrose dialysate (Dianeal; DD group, n = 30).

RESULTS

The 2 groups had similar mortality, hospitalization duration, serial C-reactive protein levels, and drop-out rates during the study. Biochemical nutritional parameters including albumin and cholesterol decreased in the DD group but remained stable or increased in the DAA group. The composite nutritional index did not differ between the 2 groups throughout the study period. Triglyceride decreased only in DAA-treated patients. Normalized protein equivalent of nitrogen appearance and dietary protein intake showed a sustained increase only in DAA patients. The nutritional benefit of DAA appeared more prominent in women, whose lean body mass and body mass index was maintained with DAA but not with DD. Mass transfer area coefficient for creatinine increased in DAA-treated patients, whereas that for urea as well as macromolecular restriction coefficients remained stable. Total Kt/V(urea) and daily ultrafiltration volume were similarly maintained in the 2 groups throughout the study.

CONCLUSION

Long-term administration of amino acid dialysate is well tolerated and presents a means to improve the nutritional status in high-risk patients. The current study, however, has not shown a significant effect of amino acid dialysate on patient survival.

Protein and energy nutrition among adult patients treated with chronic peritoneal dialysis

Protein-energy malnutrition (PEM) in adult patients treated with chronic peritoneal dialysis (CPD), which is highly prevalent and frequently severe in its manifestation, poses a significant therapeutic dilemma. The causes of PEM include inflammation, low nutrient intake, nutrient losses during dialysis, metabolic acidemia, coexisting illnesses, and possibly the endocrine disorders of uremia. Treatment strategies for PEM in CPD patients include the following: attempt to treat the potentially reversible causes of anorexia, increase nutrient intake (by nutritional counseling, oral food supplements, consideration of appetite stimulants and intraperitonial amino acid solutions), and the correction of metabolic acidosis. Coexisting illnesses engendering PEM should be treated. Experimental evidence suggests that such agents as anabolic steroids, human growth hormone, insulin-like growth factor-I, and L-carnitine may engender positive protein balance in these individuals. Finally, the use of anti-inflammatory agents to improve the nutritional status of malnourished CPD patients remains to be defined. There is a need to carry out clinical trials that examine whether an improvement in the nutritional status of CPD patients is associated with an improvement in their mortality, morbidity and/or quality of life.

Is there a survival advantage in Asian peritoneal dialysis patients?

Over the last decade, epidemiological surveys and qualitative research literature have demonstrated and validated a better survival in the Asian peritoneal dialysis population. This review summarizes the current understanding of Asian peritoneal dialysis patient survival and attempts to scrutinize the supposed survival advantage of this population group. We outlined the published peritoneal dialysis survival data from a literature search, with reference to dialysis patient cohorts from 1983 through 2002 for prevalent cases and 1980 through 2002 for incident patients. Two-year and 5-year patient survival rates in excess of 80% and 60% respectively were demonstrated in Asian countries, which compared favorably with the CANUSA, ADEMEX and most Caucasian series. Better end-stage renal disease patient survival is apparent despite a dialysis adequacy disadvantage, for reasons yet to be identified. As is the case of other racial disparities in medical care, such a difference is a product of more than biological differences and include budgetary barrier, health care system and geographic variation, physician bias and statistical pitfalls. Particular efforts should therefore be made to explore the underlying reason(s) for the Asian peritoneal dialysis patient survival advantage. Alternative approach and guidelines to peritoneal dialysis delivery in Asia might be warranted.

Dialysis adequacy and transport test for characterization of peritoneal transport type in Chinese peritoneal dialysis patients receiving three daily exchanges

Dialysis adequacy and transport test (DATT) is an accurate method to classify peritoneal transport type for continuous ambulatory peritoneal dialysis (CAPD) patients with a regimen of four exchanges of 2 L/d. We examined the accuracy of DATT for the characterization of peritoneal transport type in patients with a regimen of three exchanges of 2 L/d, which is the standard CAPD regimen in Hong Kong Chinese. We studied 189 adult Chinese CAPD patients with a prescription of three exchanges of 2 L/d. Patients who had a peritonitis episode within the previous 30 days were excluded. Standard peritoneal equilibration test (PET) and DATT were performed on consecutive days. Correlation coefficients between dialysate-to-plasma ratios of creatinine (D/P) obtained for the PET and the DATT was 0.698 (P < 0.001). Peritoneal transport type was classified according to the reported D/P creatinine reference values obtained from the PET at 4 hours. When the result was compared with the transport type classified by the DATT result using the linear regression formula derived, the Cohen kappa was 0.433 (95% confidence interval, 0.329 to 0.537), which could be regarded as a moderate level of agreement. For classification of the low transporters, the specificity of DATT was 90.1%, and sensitivity was 72.3%. For classification of the high transporters, the specificity of DATT was 96.6%, and sensitivity was 57.1%. DATT and PET had a reasonable agreement in the classification of peritoneal transport type for Chinese CAPD patients receiving a daily schedule of three exchanges of 2 L/d. Although DATT may be less accurate for CAPD patients with three daily exchanges, it remains a specific method to identify low and high transporters.

Plasminogen activator inhibitor-1 4G/5G genetic polymorphism does not affect peritoneal transport characteristic

There is evidence that type 1 plasminogen activator inhibitor (PAI-1) may have an important role in peritoneal function. We studied the effect of physiologically relevant PAI-1 promotor polymorphisms on peritoneal permeability. We performed a standard peritoneal equilibration test (PET) in 100 new continuous ambulatory peritoneal dialysis (CAPD) patients. We studied another 48 prevalent CAPD patients who had a baseline PET performed 2 years before; a standard PET was repeated on enrollment. The PAI-1 promotor polymorphism was examined. All patients then were followed up for 16.7 +/- 15.0 months. Prevalences of 4G/4G, 4G/5G, and 5G/5G genotypes were 31.8%, 46.6%, and 21.6%, respectively. Of the 100 new CAPD patients, there was no difference in net ultrafiltration (UF), dialysate-plasma (D/P) creatinine ratio at 4 hours, or mass transfer area coefficient (MTAC) of creatinine among the three genotype groups. D/P creatinine ratios at 4 hours were 0.595 +/- 0.133, 0.607 +/- 0.137, and 0.627 +/- 0.142 for the 4G/4G, 4G/5G, and 5G/5G groups, respectively (one way analysis of variance, P = 0.715). Of the 48 prevalent patients, PAI-1 genotype did not affect the longitudinal change in net UF, D/P creatinine ratio at 4 hours, or MTAC of creatinine. During follow-up, 16 patients developed peritonitis episodes that required Tenckhoff catheter removal. One patient died, 8 patients returned to long-term CAPD therapy after peritonitis resolved, and the other 7 patients developed peritoneal failure and were switched to long-term hemodialysis therapy. PAI-1 promotor genotype did not predict peritoneal failure after an episode of severe peritonitis (chi-square test, P = 0.328). We conclude that PAI-1 promotor polymorphism is not associated with peritoneal transport characteristics in stable peritoneal dialysis patients, longitudinal change in peritoneal transport, or development of peritoneal failure after an episode of severe peritonitis.

Peritoneal dialysis adequacy and risk of death

The debate on the relationship between small solute clearance and patient outcome on peritoneal dialysis has intensified in the past year with the publication or presentation of a number of important new studies. Previous studies had found a correlation between clearances and subsequent patient survival. However, this effect was all accounted for by residual renal clearance. The failure to detect an independent effect of peritoneal clearance on outcomes had been attributed to a lack of well-done studies with sufficient variation in peritoneal clearance to detect such an effect. New prospective and randomized studies suggest, however, that the relationship between peritoneal clearance and outcome is weak or absent within the usual dose ranges delivered in clinical practice. Existing clearance targets may need to be reviewed.

Impact of dialysis adequacy on the mortality and morbidity of anuric Chinese patients receiving continuous ambulatory peritoneal dialysis

Dialysis adequacy has a major impact on the outcome of continuous ambulatory peritoneal dialysis (CAPD) patients. However, most studies on peritoneal dialysis adequacy have focused on patients with significant residual renal function. The present study examined the effect of dialysis adequacy on anuric CAPD patients. A single-center prospective observational study on 140 anuric CAPD patients was performed. These patients were followed for 22.0 +/- 11.9 mo. Dialysis adequacy and nutritional indices, including Kt/V, creatinine clearance (CCr), protein equivalent nitrogen appearance, percentage of lean body mass, and serum albumin level were monitored. Clinical outcomes included actuarial patient survival, technique survival, and duration of hospitalization. In the study population, 64 were male, 36 (25.7%) were diabetic, and 59 (42.1%) were treated with 6 L exchanges per day. The body weight was 59.2 +/- 10.2 kg. Average Kt/V was 1.72 +/- 0.31, and CCr was 43.7 +/- 11.5 L/wk per 1.73m(2). Two-yr patient survival was 68.8%, and technique survival was 61.4%. Multivariate analysis showed that DM, duration of dialysis before enrollment, serum albumin, and index of dialysis adequacy (Kt/V or CCr) were independent factors of both patient survival and technique survival. It was estimated that for two patients who differed only in weekly Kt/V, a 0.1 higher value was associated with a 6% decrease in the RR of death (P: < 0.05; 95% confidence interval, 0.92 to 0.99). Serum albumin and CCr were the only independent factors that predicted hospitalization. It was found that even when there is no residual renal function, higher dialysis dosage is associated with better actuarial patient survival, better technique survival, and shorter hospitalization. Dialysis adequacy has a significant impact on the clinical outcome of CAPD patients, and the beneficial effect is preserved in anuric patients as well as in an ethnic group that has a low overall mortality.