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

Introduction

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.

The centre-calculated cutoff value is better for identifying fast peritoneal solute transfer of patients on peritoneal dialysis than the traditional value: a retrospective cohort study

Background

The mean 4-h dialysate to plasma ratio of creatinine (4-h D/Pcr) is a vital cutoff value for recognizing the fast peritoneal solute transfer rate (PSTR) in patients on peritoneal dialysis (PD); however, it shows a noticeable centre effect. We aimed to investigate our centre-calculated cutoff value (CCV) of 4-h D/Pcr and compare it with the traditional cutoff value (TCV) (0.65).

Methods

In this study, we enrolled incident PD patients at our centre from 2008 to 2019, and divided them into fast or non-fast PSTR groups according to baseline 4-h D/Pcr-based CCV or TCV. We compared the efficiency of the fast PSTR recognized by two cutoff values in predicting mortality, ultrafiltration (UF) insufficiency and technical survival.

Results

In total, 1905 patients were enrolled, with a mean 4-h D/Pcr of 0.71 ± 0.11. Compared with TCV (0.65), CCV (0.71) showed superiority in predicting mortality of PD patients [hazard ratio (HR) 1.27, 95% confidence interval (CI) 1.02-1.59 vs HR 1.24, 95% CI 0.97-1.59]. The odds ratio (OR) of the fast PSTR in centre classification was slightly higher than traditional classification in predicting UF insufficiency (OR 1.67, 95% CI 1.25-2.24 vs OR 1.60, 95% CI 1.15-2.22). Additionally, the restricted cubic splines 4-h D/Pcr has an S-shaped association with mortality and UF insufficiency, and the inflection points of 4-h D/Pcr were 0.71 (equal to CCV).

Conclusions

The CCV of 4-h D/Pcr for identifying fast PSTR was 0.71. It was superior to TCV in predicting mortality and UF insufficiency.

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.

Risk Factors for Cardiovascular Disease in Patients Undergoing Peritoneal Dialysis

Patients on peritoneal dialysis (PD) are at high cardiovascular risk. Although some risk factors are unmodifiable (for example, age, sex, genetics), others are exacerbated in the unfriendly uremic milieu (inflammation, oxidative stress, mineral disturbances) or contribute per se to kidney disease and cardiovascular progression (diabetes mellitus, hypertension). Moreover, several factors associated with PD therapy may both increase (by altered lipid profile, hyperinsulinemia, and formation of advanced glycation end-products) and decrease (by better blood pressure control and anemia management) cardiovascular risk. The present review discusses recent findings and therapy trends in cardiovascular research on the PD population, with emphasis on the roles of inflammation, insulin resistance, homocysteinemia, dyslipidemia, vascular calcification, and genetics/epigenetics.

Peritonitis-Related Mortality in Patients Undergoing Chronic Peritoneal Dialysis

Peritonitis is a well-known cause of mortality in peritoneal dialysis (PD) patients. We carried out a retrospective study to disclose the clinical spectrum and risk profile of peritonitis-related mortality. We analyzed 693 episodes of infectious peritonitis suffered by 565 patients (follow-up 1149 patient-years). Death was the final outcome in 41 cases (5.9% of episodes), peritonitis being directly implicated in 15.2% of the global mortality and 68.5% of the infectious mortality observed. In 41.5% of patients with peritonitis-related mortality, the immediate cause of death was a cardiovascular event. Highest mortality rates corresponded to fungal (27.5%), enteric (19.3%), and Staphylococcus aureus (15.2%) peritonitis. Multivariate analysis disclosed that the baseline risk of peritonitis-related mortality was significantly higher in female [relative risk (RR) 2.13, 95% confidence interval (CI) 1.24 – 4.09, p = 0.02], older (RR 1.10/year, CI 1.06 – 1.14, p < 0.0005), and malnourished patients (RR 2.51, CI 1.21 – 5.23, p = 0.01) with high serum C-reactive protein (s-CRP) levels (RR 4.04, CI 1.45 – 11.32, p = 0.008) and a low glomerular filtration rate (RR 0.75 per mL/minute, CI 0.64 – 0.87, p < 0.0005). Analysis of risk after a single episode of peritonitis and/or subanalysis restricted to peritonitis caused by more aggressive micro-organisms disclosed that overall comorbidity [odds ratio (OR) 1.21, CI 1.05 – 1.71, p = 0.005], depression (OR 2.35, CI 1.14 – 4.84, p = 0.02), and time on PD at the time of the event (OR 1.02/month, CI 1.00 – 1.03, p = 0.02) were other predictors of mortality.

In summary, the etiologic agent is a definite marker of peritonitis-related mortality but gender, age, residual renal function, inflammation (s-CRP), malnutrition, and depression are other significant correlates of this outcome. Most of these risk factors are common to cardiovascular and peritonitis-related mortality, which may explain the high incidence of cardiovascular event as the immediate cause of death in patients with peritonitis-related mortality.

Chronic Inflammation in Peritoneal Dialysis: The Search for the Holy Grail?

Mortality and morbidity in chronic kidney disease (CKD) patients are unacceptably high. The annual mortality rate due to cardiovascular disease (CVD) is approximately 9%, which, for the middle-aged person, is at least 10- to 20-fold higher than for the general population. Classic risk factors for CVD are highly prevalent in CKD patients, but they cannot fully account for the excessive rate of CVD in this population. Instead, it has become increasingly clear that nontraditional risk factors, such as systemic inflammation, may play a key role in the development of atherosclerosis. It is well established that inflammatory markers are very powerful predictors of high CVD morbidity and mortality not only in the general population, but particularly in CKD patients. Signs of a sustained low-grade inflammation, such as increased levels of C-reactive protein (CRP), are present in the majority of stage 5 CKD patients, even in patients in clinically stable condition, and they are also commonly observed after the initiation of dialysis therapy. Dialysis therapy — hemodialysis as well as peritoneal dialysis (PD) — may itself contribute to systemic inflammation. Local intraperitoneal inflammation can also occur in patients treated with PD. These local effects may result in a low-grade inflammation, caused by the bioincompatibility of conventional glucose-based dialysis fluids, to intense inflammation associated with peritonitis. Given these circumstances, it is reasonable to hypothesize that strategies aiming to reduce inflammation are potentially important and novel, and could serve to reduce CVD, thereby lowering morbidity and mortality in patients with CKD. In this review we provide information supporting the hypothesis that systemic inflammation is tightly linked to the most common complications of CKD patients, in particular those on PD, and that local inflammation in PD may contribute to various related complications. The aims of this review are to discuss the reasons that make inflammation an attractive target for intervention in CKD, the particular aspects of the inflammation–CVD axis during PD treatment that are likely involved, and possible means for the detection and management of chronic inflammation in PD patients.

Inflammation in Peritoneal Dialysis: A Latin-American Perspective

Peritoneal dialysis (PD) patients present an extremely high mortality rate, but the mechanisms mediating the increased risk of mortality observed in this group of patients are still largely unknown, which limits the perspective of effective therapeutic strategies. The leading hypothesis that tries to explain this high mortality risk is that PD patients are exposed to a number of traditional risk factors for cardiovascular disease (CVD) already at the onset of their chronic kidney disease (CKD), since many of these risk factors are common to both CVD and CKD. Of particular importance, chronic inflammation recently emerged as an important novel risk factor related to multiple complications of CKD. There are many stimuli of the inflammatory response in CKD patients, such as fluid overload, decreased cytokine clearance, presence of uremia-modified proteins, presence of chronic infections, metabolic disturbances (including hyperglycemia), obesity. Many of these factors are related to PD. Latin America has made some progress in economic issues; however, a large portion of the population is still living in poverty, in poor sanitary conditions, and with many health-related issues, such as an increasing elderly population, low birth weights, and increasingly high energy intake in the adult population, which, in combination with changes in lifestyle, has provoked an increase in the prevalence of obesity, diabetes, and CVD. Therefore, in Latin America, there seems to be a peculiar situation combining high prevalence of low education level, poor sanitary conditions, and poverty with increases in obesity, diabetes, and sedentary lifestyle. Since inflammation and mortality risk are intimately related to both sides of those health issues, in this review we aim to analyze the peculiarities of inflammation and mortality risk in the Latin-American PD population.

Are We Underestimating the Problem of Ultrafiltration in Peritoneal Dialysis Patients?

Background

Accurate measurement of ultrafiltration (UF) is important to improve the morbidity and mortality of peritoneal dialysis (PD) patients. The introduction of “flush-before-fill” PD systems has led to improved peritonitis rates. Partly to compensate for dialysate lost during flush-before-fill, extra dialysate was added to each PD bag. A 2-L PD bag now contains a mean volume of 2.225 L. That overfill volume might be erroneously measured as UF. We previously studied how this confounding factor might be affecting the diagnosis of UF failure and found that almost all units were overestimating daily UF by 900 mL. We now repeat the study to determine if the accuracy of UF estimation has improved.

Methods

We conducted a telephone survey of PD units in the UK to determine how drain bags are weighed and how UF is calculated during formal assessment of adequacy and the peritoneal equilibrium test (PET). We also retrospectively analyzed our last 100, 24-hour dialysate collections and PET results to determine the potential clinical impact of overestimating UF.

Results

There has been an improvement since our last study, but 70% of PD units in the UK are still overestimating daily UF in patients on continuous ambulatory PD (CAPD). Half the surveyed units also inaccurately calculate UF during the PET, and 85% were reporting results of PET and 24-hour dialysate collections through the software provided by Baxter Healthcare. By including the overfill volume, 73% of patients with daily UF <750 mL would not be diagnosed as having inadequate daily UF (assuming that all were fluid overloaded and anuric). Similarly, 73% with potential UF failure during the PET (4-hour UF <100 mL) would be missed if overfill volume was misrepresented as UF.

Conclusion

For patients undergoing CAPD, there requires standardization on when drain bags are weighed. Awareness that calculation of UF must exclude overfill volumes has improved but remains poor. The PD Adequest software (Baxter Healthcare, Compton, UK) is widely adopted in the UK and perhaps it could draw attention of users to the potential of UF overestimation in CAPD patients.

Inflammation and Extracellular Volume Expansion are Related to Sodium and Water Removal in Patients on Peritoneal Dialysis

Background

Inflammation is an important risk for mortality in dialysis patients. Extracellular fluid volume (ECFv) expansion, a condition commonly seen in peritoneal dialysis (PD) patients, may be associated with inflammation. However, published support for this relationship is scarce.

Objectives

To quantify the proportion of patients on PD with inflammation and to analyze the role of ECFv expansion and the factors related to these conditions.

Design

A prospective, multicenter cross-sectional study in six hospitals with a PD program.

Patients and Methods

Adult patients on PD were studied. Clinical data, body composition, and sodium and fluid intake were recorded. Biochemical analysis, C-reactive protein (CRP), and peritoneal and urinary fluid and sodium removal were also measured.

Results

CRP values positive (≥ 3.0 mg/L) for inflammation were found in 147 (80.3%) and negative in 36 patients. Patients with positive CRP had higher ECFv/total body water (TBW) ratio (women 47.69 ± 0.69 vs 47.36 ± 0.65, men 43.15 ± 1.14 vs 42.84 ± 0.65; p < 0.05), higher serum glucose (125.09 ± 81.90 vs 103.28 ± 43.30 mg/dL, p < 0.03), and lower serum albumin (2.86 ± 0.54 vs 3.17 ± 0.38 g/dL, p < 0.001) levels. They also had lower ultrafiltration (1003 ± 645 vs 1323 ± 413 mL/day, p < 0.005) and total fluid removal (1260 ± 648 vs 1648 ± 496 mL/day, p < 0.001), and less peritoneal (15.59 ± 162.14 vs 78.11 ± 110.70 mEq/day, p < 0.01) and total sodium removal (42.06 ± 142.49 vs 118.60 ± 69.73 mEq/day, p < 0.001). In the multivariate analysis, only ECFv/TBW was significantly ( p < 0.04) and independently associated with inflammation. ECFv/TBW was correlated with fluid removal ( r = 0.16, p < 0.03) and renal sodium removal ( r = 0.2, p < 0.01).

Conclusion

The data suggest that ECFv expansion may have a significant role as an inflammatory stimulus. The results disclose a relationship between the two variables, ECFv expansion and inflammation, identified as independent risk factors for mortality in PD patients.

Serum BNP Concentration and Left Ventricular Mass in CAPD and Automated Peritoneal Dialysis Patients

Objective

To compare ultrafiltration under continuous ambulatory peritoneal dialysis (CAPD) and automated PD (APD), disclosing potential effects on serum B-type natriuretic peptide (BNP) levels and echocardiographic findings.

Patients and Methods

This cross-sectional clinical study included 32 patients on CAPD and 30 patients on APD without clinical evidence of heart failure or hemodynamically significant valvular heart disease. Peritoneal equilibration tests, BNP levels, and echocardiographic measurements were performed in each subject. BNP measurements were also performed in 24 healthy control subjects.

Results

Patients on APD had lower ultrafiltration and higher values of BNP and left ventricular mass index (LVMI) compared with patients on CAPD (respectively: 775 ± 160 vs 850 ± 265 mL, p = 0.01; 253.23 ± 81.64 vs 109.42 ± 25.63 pg/mL, p = 0.001; 185.12 ± 63.50 vs 129.30 ± 40.95 g/m2, p = 0.001). This occurred despite higher mean dialysate glucose concentrations and far more extensive use of icodextrin in the APD group.

Conclusion

Treatment with APD is associated with higher plasma BNP levels and LVMI compared to CAPD. This may be the result of chronic fluid retention caused by lower ultra-filtration in APD patients.

High Peritoneal Permeability is Not Associated with Higher Mortality or Technique Failure in Patients on Automated Peritoneal Dialysis

Background

Patients on continuous ambulatory peritoneal dialysis (CAPD) who have high small-molecule peritoneal transport have increased mortality.

Objective

To investigate the impact of baseline peritoneal transport characteristics on patient and technique survival in incident peritoneal dialysis (PD) patients, most of whom are on automated PD (APD), with the use of icodextrin.

Design

Retrospective observational cohort study.

Setting

A single PD unit.

Patients and Methods

193 new patients that began PD between January 2000 and September 2004, and had an initial peritoneal equilibration test within 6 months of commencement of PD. Patients were divided into low (L), low average (LA), high average (HA), and high (H) peritoneal transport groups. Death-censored technique failure and patient survival were examined.

Results

Of the 193 patients, 151 (78.1%) were on APD or on APD with icodextrin or on CAPD with icodextrin. At the end of 1, 3, and 5 years, patient survival was 91%, 82%, and 67% in LA group; 95%, 77%, and 69% in HA group; and 96%, 71%, and 71% in H group. Technique survival was 100%, 90%, and 77% in LA group; 96%, 84%, and 72% in HA group; and 92%, 87%, and 77% in H group. High peritoneal permeability did not predict worse patient survival or technique failure, while age, diabetes, a lower glomerular filtration rate, and high body mass index (≥ 30 kg/m2) were independent predictors of death.

Conclusion

This study suggests that higher peritoneal transport is not a significant independent risk factor for either mortality or death-censored technique failure. The favorable outcome for high transporters in this study may be due to improved management of volume status by the increased use of APD and the use of icodextrin-based dialysis fluid.

Can the Inflammation Markers of Patients with High Peritoneal Permeability on Continuous Ambulatory Peritoneal Dialysis be Reduced on Nocturnal Intermittent Peritoneal Dialysis?

Background

Patients with high peritoneal permeability have the greatest degree of inflammation on continuous ambulatory peritoneal dialysis (CAPD), which may be associated with their higher mortality. Nocturnal intermittent peritoneal dialysis (NIPD; “dry day”) may decrease inflammation by reducing the contact between dialysate and peritoneum and/or providing better fluid overload control. Therefore, the aims of this study were to determine and compare serum and dialysate concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) of patients with high or high-average peritoneal transport on CAPD, changed to NIPD, and ultimately to continuous cyclic peritoneal dialysis (CCPD).

Methods

Crossover clinical trial in 11 randomly selected patients. All subjects had been on CAPD and were changed to NIPD, and ultimately to CCPD (6.4 ± 3.1 months after initiation of study). All patients used glucose-based dialysate. Evaluations of clinical and biochemical parameters, dialysis adequacy, and serum and dialysis inflammation markers were performed at baseline on CAPD, 7 – 14 days after changing to NIPD, 7 – 14 days after switching to CCPD, and after 1 year of follow-up. All patients used only 1.5% glucose dialysate during evaluation days. CRP was determined by nephelometry, and IL-6 and TNF-α by ELISA.

Results

Seven patients were high transporters and 4 high average. Ultrafiltration increased ( p < 0.05) when patients changed from CAPD [0.38 L (-0.3 – 1.1 L)] to NIPD [2.64 L (0.7 – 4.7 L)]; it then decreased on CCPD [0.88 L (0.4 – 1.3 L) and at the end of study [0.65 L (0.3 – 1.0 L)]. This better fluid overload control was accompanied by decreased weight and systolic and diastolic blood pressure when patients changed from CAPD (89 ± 13 kg, 160 ± 23 and 97 ± 9 mmHg, respectively) to NIPD (86 ± 17 kg, 145 ± 14 and 86 ± 9 mmHg, respectively), and increased weight and systolic and diastolic blood pressure on CCPD (85 ± 15 kg, 143 ± 23 and 88 ± 14 mmHg, respectively) and at the end of follow-up (87 ± 16 kg, 155 ± 24 and 89 ± 12 mmHg, respectively). Median serum CRP decreased ( p = 0.03), from 3.8 (1.6 – 8.5) mg/L on CAPD to 1.0 (0.4 – 4.4) mg/L on NIPD, but increased on CCPD [1.8 (1.3 – 21) mg/L] and at the end of the study [3.2 (0.3 – 8.2) mg/L]. Dialysate CRP decreased nonsignificantly, from 0.10 (0 – 0.5) mg/L on CAPD to 0 (0 – 0.03) mg/L on NIPD, to 0.01 (0 – 0.08) mg/L on CCPD, and to 0 (0 – 0) mg/L at final evaluation. Serum TNF-α concentration decreased, from 0.14 (0.04 – 0.6) pg/mL on CAPD to 0.01 (0 – 0.08) pg/mL on NIPD, and then increased to 0.06 (0 – 0.4) pg/mL on CCPD and to 0.11 (0 – 0.2) pg/mL at the end of the study; whereas dialysate TNF-α decreased, from 0.08 (0.03 – 0.2) pg/mL on CAPD to 0.04 (0 – 0.2) pg/mL on NIPD, and to 0 (0 – 0) pg/mL and 0 (0 – 0.05) pg/mL on CCPD and final evaluation respectively. Serum IL-6 decreased ( p = 0.07), from 2.5 (2.0 – 4.2) pg/mL on CAPD to 1.0 (0.7 – 2.0) pg/mL on NIPD, and to 1.0 (0.8 – 2.9) pg/mL on CCPD and 1.0 (0.5 – 9.8) pg/mL at the end of the study; whereas dialysate levels remained similar on CAPD [8.0 (3.7 – 13) pg/mL] and NIPD [7.8 (5.1 – 23) pg/mL], and increased on CCPD [11.2 (9.5 – 19) pg/mL] and at final evaluation [11.2 (8.3 – 15) pg/mL].

Conclusions

NIPD significantly decreased serum CRP and displayed a trend to decrease TNF-α and IL-6 serum concentrations compared with CAPD; whereas CCPD tended to reverse these effects. These results did not appear to be due to decreased local peritoneal inflammation, but they could be associated with better control of fluid overload on NIPD. Thus, NIPD, as long as the residual renal function allows it, may be useful in reducing the systemic inflammation of patients with high peritoneal membrane permeability.

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.

Membrane transport status does not predict peritonitis risk in patients on peritoneal dialysis

AIM

The aim of this study is to determine whether peritoneal membrane transport status (MTS) is associated with peritonitis or poor peritoneal dialysis-related outcomes.

METHODS

This retrospective cohort study analysed data of incident adult patients on peritoneal dialysis in Western Sydney between 1 October 2003 and 31 December 2012. Only patients who underwent peritoneal equilibration and adequacy tests within 6 months of commencement were included. Kaplan-Meier survival curves for time until first peritonitis and time until composite endpoint of peritonitis, death or technique failure, censored for transplant, were constructed.

RESULTS

About 397 patients, mean age 58.8(+/-2SD29) years, body mass index (BMI) 26.6(+/-5) kg/m² and serum albumin 35.4(+/-5) g/L were included. About 59.2% had high/high-average peritoneal MTS; 45.8% were past and current smokers; 51.9% developed at least one episode of peritonitis; 7.6% changed to haemodialysis; 6.3% underwent transplantation; 8.8% died; and 25.4% remained free of the aforementioned events over a mean follow-up period of 22.5 months (range 0-115 months). Peritoneal MTS was not associated with time to first peritonitis (p = 0.67) or composite endpoint of peritonitis, death or technique failure (p = 0.12). Smoking and hypoalbuminaemia independently predicted time to first peritonitis. Past and current smokers had a hazard ratio of 1.38 (95% CI 1.03-1.86) for shorter time to first peritonitis, significant after adjustment for serum albumin (p = 0.033). Serum albumin <32 g/L had a hazard ratio of 1.74 (95% CI 1.13-2.67) for shorter time to first peritonitis, significant after adjusting for smoking (p = 0.012).

CONCLUSION

Smoking and hypoalbuminaemia, but not MTS, were associated with shorter time to first peritonitis and composite endpoint of peritonitis, death and technique failure.

Novel Equations for Estimating Lean Body Mass in Peritoneal Dialysis Patients

♦

OBJECTIVES

To develop and validate equations for estimating lean body mass (LBM) in peritoneal dialysis (PD) patients. ♦

METHODS

Two equations for estimating LBM, one based on mid-arm muscle circumference (MAMC) and hand grip strength (HGS), i.e., LBM-M-H, and the other based on HGS, i.e., LBM-H, were developed and validated with LBM obtained by dual-energy X-ray absorptiometry (DEXA). The developed equations were compared to LBM estimated from creatinine kinetics (LBM-CK) and anthropometry (LBM-A) in terms of bias, precision, and accuracy. The prognostic values of LBM estimated from the equations in all-cause mortality risk were assessed. ♦

RESULTS

The developed equations incorporated gender, height, weight, and dialysis duration. Compared to LBM-DEXA, the bias of the developed equations was lower than that of LBM-CK and LBM-A. Additionally, LBM-M-H and LBM-H had better accuracy and precision. The prognostic values of LBM in all-cause mortality risk based on LBM-M-H, LBM-H, LBM-CK, and LBM-A were similar. ♦

CONCLUSIONS

Lean body mass estimated by the new equations based on MAMC and HGS was correlated with LBM obtained by DEXA and may serve as practical surrogate markers of LBM in PD patients.

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.

A Pilot Study Examining the Effects of Tolvaptan on Residual Renal Function in Peritoneal Dialysis for Diabetics

BACKGROUND

For patients with end-stage renal disease (ESRD), peritoneal dialysis (PD) serves as a possible renal replacement therapy. However, most PD patients, particularly those with ESRD and diabetes mellitus, reportedly discontinue PD early, resulting in shorter survival periods and poorer prognosis because of overhydration. Recently, the vasopressin-2 receptor antagonist tolvaptan was approved for volume control in patients with heart failure. The present study aimed to identify the effects of tolvaptan in diabetic PD patients.

METHODS

In this pilot study, the tolvaptan group (n = 12) were treated with 15 mg/day of tolvaptan 2 weeks after PD initiation and were prospectively analyzed for 1 year, and patients in the control group (n = 12) did not receive tolvaptan and were retrospectively analyzed for 1 year. In addition to the biochemical tests, echocardiograms, serum atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels, peritoneal Kt/V, and creatinine clearance (CCr) were examined at baseline and at 6 and 12 months after PD initiation.

RESULTS

In the control group, the urine volume, renal Kt/V, and renal CCr levels consistently decreased; however, these parameters were stably maintained during the study period in the tolvaptan group. Atrial natriuretic peptide, CRP levels and the left ventricular mass index of the tolvaptan-treated group were significantly lower than those in the control group, whereas total protein and albumin levels were significantly higher at 6 and 12 months in the tolvaptan group. There were no obvious adverse effects.

CONCLUSIONS

These data suggest that tolvaptan may preserve residual renal function and improve volume control in PD patients with diabetes mellitus.

Time-dependent associations between total sodium removal and mortality in patients on peritoneal dialysis

PURPOSE

To determine if the time-dependent association between total sodium removal and mortality in patients on continuous ambulatory peritoneal dialysis (CAPD) is confounded by markers of diet and nutrition.

METHODS

The study enrolled 305 incident patients who started CAPD between July 2002 and February 2007. All patients were followed until death or censoring in February 2008. Demographics, blood pressure, and markers of volume and inflammation were collected at baseline. Biochemistry, fluid and solute removal, and diet and nutrition parameters were collected quarterly and thus calculated as time-averaged values.

RESULTS

Mean age of the study patients was 59.4 years, 42.3% were men, and 40.3% had diabetes. During the 31.4-month follow-up, 74 patients died. The time-averaged daily total sodium removal (TSR) in the overall cohort was 2.67 g (range: 2.02 g-3.47 g). Participants with a high time-averaged TSR tended to experience higher fluid, sodium, urea, and creatinine removal, mainly as a result of better residual renal function (RRF). They also had a higher nutrient intake and a higher lean body mass. Time-dependent TSR was an independent predictor of death, including when adjusted for age, Charlson index, time-dependent hemoglobin, RRF, and peritoneal transport rate (hazard ratio: 0.84; 95% confidence interval: 0.70 to 1.00; p=0.05), but the predictive effect disappeared in multivariate models after further individual adjustment for time-dependent total energy intake, total protein intake, serum albumin, and lean body mass. By contrast, the predictive effect did not disappear if the only adjustment was for time-dependent RRF.

CONCLUSIONS

The time-dependent association between TSR and mortality in patients on peritoneal dialysis can be largely explained by diet and nutrition parameters.

Arterial pulse wave velocity and peritoneal transport characteristics independently predict hospitalization in Chinese peritoneal dialysis patients

OBJECTIVE

Cardiovascular disease (CVD) is the most common cause of mortality in chronic peritoneal dialysis (PD) patients. Increased arterial stiffness may be related to a high peritoneal permeability resulting in fluid overload in PD patients. We studied the relations between arterial stiffness, peritoneal transport, and radiographic parameters of systemic fluid overload in a cohort of Chinese PD patients.

DESIGN

Prospective cohort study.

SETTING

University referral center.

PATIENTS

We studied 107 PD patients. Vascular pedicle width and cardiothoracic ratio were measured from a plain postero-anterior chest radiograph. Pulse wave velocity (PWV) was determined at carotid-femoral (C-F) and carotid-radial sites. Peritoneal transport was determined by the dialysate-to-plasma ratio (D/P) of creatinine at 4 hours of dwell. Patients were followed for 9.4 +/- 4.6 months.

OUTCOME MEASURES

Duration of hospitalization; actuarial and technique survival.

RESULTS

There were no relationships between radiographic measures, arterial PWV, and D/P creatinine. However, both C-F PWV and D/P creatinine were independent predictors of the number of hospitalizations for CVD. None of the parameters correlated with mortality in this study.

CONCLUSIONS

There were no relationships between radiological parameters of fluid overload, peritoneal transport characteristics, and arterial PWV. Both C-F PWV and D/P creatinine were independent predictors of the number of hospitalizations for CVD. Our result suggests that arterial stiffness and high peritoneal transport each contribute to the development of CVD in this group of patients.

Initial high peritoneal transport status is not a predictor of mortality in peritoneal dialysis patients

OBJECTIVE

Initial high peritoneal permeability in peritoneal dialysis (PD) patients was previously thought to be a poor prognostic factor. We aimed to study the factors that determine the initial transport status and prognosis in PD patients.

METHODS

This was an observation cohort study that enrolled 551 fresh uremic patients who commenced PD in a single PD center from January 1994 to December 2004. Patients with different initial peritoneal transport status were analyzed and determinants of the initial peritoneal transport status were evaluated. All patients were followed up to investigate the risks of mortality.

RESULTS

At the start of PD, only age and sex were determinants of the initial peritoneal transport status upon multiple linear regression analysis. The average duration of the study follow-up was 45.4 +/- 29.4 months. In the follow-up, a regression toward mean of transport status was found. About 107 patients died during the observation period. Cox-multivariate analysis revealed only age (RR = 1.06, p < 0.001), comorbidity index (RR = 2.31, p < 0.001), serum albumin (RR = 0.58, p = 0.008), and percentage of lean body mass (RR = 0.97, p = 0.008) to be independent predictors of mortality.

CONCLUSION

We observed that the initial peritoneal transport status is not a determinant factor of long-term mortality. The reason may be due to a consequence of regression toward mean of the transport status. Whether the observed longitudinal regression-to-mean phenomenon change represent any physiologic relevance is hard to define. Further studies on the underlying mechanisms are needed.

Superior survival of high transporters treated with automated versus continuous ambulatory peritoneal dialysis

BACKGROUND

Automated peritoneal dialysis (APD) is widely recommended for the management of high transporters by the International Society of Peritoneal Dialysis (ISPD), although there have been no adequate studies to date comparing the outcomes of APD and continuous ambulatory peritoneal dialysis (CAPD) in this high risk group.

METHODS

The relative impact of APD versus CAPD on patient and technique survival rates was examined by both intention-to-treat (PD modality at Day 90) and 'as-treated' time-varying Cox proportional hazards model analyses in all patients who started PD in Australia or New Zealand between 1 April 1999 and 31 March 2004 and who had baseline peritoneal equilibration tests confirming the presence of high peritoneal transport status.

RESULTS

During the study period, 4128 patients commenced PD. Of these, 628 patients were high transporters on PD at Day 90 (486 on APD and 142 on CAPD). Compared to high transporters treated with CAPD, APD-treated high transporters were more likely to be younger and Caucasian, and less likely to be diabetic. On multivariate intention-to-treat analysis, APD treatment was associated with superior survival [adjusted hazard ratio (HR) 0.56, 95% confidence interval (CI) 0.35-0.87] and comparable death-censored technique survival (HR 0.88, 95% CI 0.64-1.21). Superior survival of high transporters treated with APD versus CAPD was also confirmed in supplemental as-treated analysis (HR 0.72, 95% CI 0.54-0.96), matched case-control analysis (HR 0.60, 95% CI 0.36-0.96) and subgroup analysis of high transporters treated entirely with APD versus those treated entirely with CAPD (HR 0.29, 95% CI 0.14-0.60). There were no statistically significant differences in patient survival or death-censored technique survival between APD and CAPD for any other transport group, except for low transporters, who experienced a higher mortality rate on APD compared with CAPD (HR 2.19, 95% CI 1.02-4.70).

CONCLUSIONS

APD treatment is associated with a significant survival advantage in high transporters compared with CAPD. However, APD treatment is associated with inferior survival in low transporters.

Simulating inadequate dialysis and its correction using an individualized patient-derived nomogram

Computerized kinetic modeling is a valuable automated peritoneal dialysis (APD) prescription tool for optimizing dialysis adequacy. However, non-compliance results in failure to achieve adequacy targets. The aim of this study was to determine if a nomogram could estimate dialysis compensations for shortfalls in simulated non-compliant patients, such that total weekly urea clearance (Kt/V(urea)) targets are met. Individualized nomograms comprising a series of curves were derived from PD Adequest (ver. 2.0)-predicted Kt/V(urea) data (r (2 ) > 0.99) for different APD prescriptions. The nomogram was then used to estimate the (Nomogram-computed) average of the daily Kt/V(urea) in 14 patients. The study comprised three 1-month phases. Patients were compliant to dialysis in phase I, where Adequest-predicted Kt/V(urea) showed good agreement with both measured (r (I) = 0.72), and Nomogram-computed values (r (I) > 0.99) (p < 0.001). Conversely, in non-compliant phase II, Nomogram-computed values were lower than Adequest-predicted values (p < 0.002). In phase III, the nomogram estimated prescription adjustments required to compensate for shortfalls, such that there was significantly less difference between Nomogram-computed and Adequest-predicted Kt/V(urea) than in phase II (p = 0.005). Thus, despite non-compliance, predicted Kt/V(urea) targets were attained using the nomogram to adjust the daily APD prescriptions. This concept is potentially useful for patients desiring to compensate for inadvertent shortfalls, rather than for 'truly non-compliant' patients.

Impact of dialysis duration and glucose absorption on nutritional indices in stable continuous ambulatory peritoneal dialysis patients

OBJECTIVE

The presence of comorbidity is a risk factor for both poor nutrition and poor outcome in continuous ambulatory peritoneal dialysis (CAPD) patients. In CAPD specifically, peritoneal glucose load is associated with a possible suppression of appetite, contributing to protein malnutrition. This study sought to explore the factors associated with malnutrition indices in stable peritoneal dialysis patients without significant comorbidity, and to assess the impact of peritoneal glucose absorption on nutrition parameters.

DESIGN

This was a cross-sectional observational study.

SETTING

This study took place in the peritoneal dialysis department of a university hospital, and involved outpatients.

PATIENTS

There were 23 stable, comorbidity-free CAPD patients (9 women), aged 54 +/- 12 years, with a CAPD duration of 28 +/- 25 months (values are mean +/- SD unless otherwise noted).

METHODS

Nutritional status was evaluated by means of anthropometric and serum measurements. A peritoneal equilibration test was performed, and daily glucose absorption was measured. Lean body mass (LBM) was assessed through creatinine kinetics.

RESULTS

A significant impact of CAPD duration was found. Patients in the upper quartile of CAPD duration had worse nutritional parameters compared with the rest of the group: their mid-upper-arm surface area and fat surface area were lower (65 +/- 9 cm(2) vs. 78 +/- 6.2 cm(2) and 16 +/- 5.3 cm(2) vs. 26 +/- 9.5 cm(2), respectively, P < .05), their albumin concentration was lower (36 +/- 0.5 g/L vs. 42 +/- 4 g/L, P < .05), and their cholesterol and triglycerides were lower (3.5 +/- 0.5 vs. 5.2 +/- 1 mmol/L and 1.3 +/- 0.6 vs. 2.3 +/- 1.1 mmol/L, respectively, P < .05). No significant correlations between peritoneal glucose absorption and these indices were found.

CONCLUSION

The duration of dialysis treatment, but not peritoneal glucose absorption, is a predictor of malnutrition in stable, comorbidity-free CAPD patients.

Contrasting clinical outcomes between different modes of peritoneal dialysis regimens: two center experiences in China

In the present study, we compared the clinical outcomes between two different modes of peritoneal dialysis (PD) and explored the possible role of volume overload in continuous ambulatory peritoneal dialysis (CAPD) patients. A longitudinal and a cross-sectional study were included. Patients received either an 'adaptative ultrafiltration (UF)' PD regimen, which focused on gradually increasing peritoneal ultrafiltration (PDi group), or traditional PD treatment (PDt group). Patients' demographic characteristics, nutritional status, fluid removal as well as fluid status were recorded. In the cross-sectional study, all clinically stable patients who were treated with CAPD for at least three months were enrolled and grouped according to their time on dialysis: short term, medium term, and long term. Both studies showed that PDi and PDt patients had distinct fluid removal patterns. PDt patients had decreased total fluid removal with worsening fluid status and deteriorating nutritional status, whereas PDi patients remained rather stable in relation to fluid removal, fluid status, and improving nutritional status. Cox regression analysis confirmed that the PDi group had better patient survival than the PDt group. Our data suggest that traditional and 'adaptative UF' PD therapy may have distinct fluid removal patterns over time on dialysis, and this unique pattern might partly explain the still unacceptable high mortality of long-term CAPD patients.

Correlations of lean body mass with nutritional indicators and mortality in patients on peritoneal dialysis

Detection of malnutrition in dialysis patients is important since this is a predictor of morbidity and mortality. Lean body mass (LBM) reflects the somatic protein store and this was measured by creatinine kinetics, anthropometry, and biometric impedance in 210 incident Chinese patients on continuous ambulatory peritoneal dialysis. The study was started in the third month of dialysis and the patients were followed for an average of 29 months. We devised three models of survival by combining the three different LBM measures with several nutritional markers and recognized outcome predictors. Follow-up was censored for transplantation or transfer to hemodialysis with an end point of death while on peritoneal dialysis. Statistical correlations were observed among the LBM values determined by all the three methods and these correlated significantly with both left and right hand grip strength but not with nutritional markers. LBM by creatinine kinetics, mean arterial pressure, and the calcium-phosphorus product were significant, independent predictors of death in one survival model. Anthropometry and bioelectric impedance were not significant predictors of death in the other two models. Our study suggests that LBM measured by creatinine kinetics, anthropometry, and bioelectrical impedance correlates well with the somatic protein store but not with the general nutritional status.

Amiloride-sensitive sodium channels on the parietal human peritoneum: evidence by ussing-type chamber experiments

The mesothelium is part of the peritoneal water and ion transport barrier essential for peritoneal dialysis (PD) treatment and has a central role in the pathogenesis of peritoneal fibrosis and ultrafiltration failure observed in many PD patients. We investigated the effect of amiloride on the transmesothelial electrical resistance (RTM) of isolated parietal human peritoneum. Intact sheets were obtained from seven patients (three men, four women; mean age, 64 +/- 8 years). Fourteen peritoneal planar sheets were transferred to the laboratory in oxygenated Krebs-Ringer bicarbonate solution at 4 degrees C within 30 minutes after removal and mounted in an Ussing-type chamber. Amiloride (10(-3) mol/L) added apically (n = 8) caused a rapid rise of the RTM to 24.15 +/- 0.76 [OMEGA]H cm2 and a subsequent value persistence (p < 0.05); added basolaterally (n = 6), it increased the RTM to 22.66 +/- 0.59 [OMEGA]H cm2 within 1 minute, which persisted throughout the experiment. RTM was measured before and serially for 30 minutes after addition of amiloride. Control RTM was 20.29 +/- 0.86 [OMEGA]H cm2. These results indicate a rapid inhibitory effect of amiloride on the ionic permeability of parietal human peritoneum. The increase in the RTM observed after addition of amiloride clearly indicates the existence of amiloride-sensitive sodium channels on the human parietal peritoneal membrane, which may play some role in the ultrafiltration process and sodium removal during PD.

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.

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.

Higher peritoneal transport status is associated with higher mortality and technique failure in the Australian and New Zealand peritoneal dialysis patient populations

Although early studies observed that peritoneal membrane transport characteristics were determinants of morbidity and mortality in peritoneal dialysis (PD) patients, more recent investigations, such as the Ademex trial, have refuted these findings. The aim of this study was to determine whether baseline peritoneal transport status predicted subsequent survival in Australian and New Zealand PD patients. The study included all adult patients in Australia and New Zealand who commenced PD between April 1, 1999, and March 31, 2004, and had a peritoneal equilibration test (PET) performed within 6 mo of PD commencement. Times to death and death-censored technique failure were examined by Kaplan-Meier analyses and multivariate Cox proportional hazards models. PET measurements were available in 3702 (72%) of the 5170 individuals who began PD treatment in Australia or New Zealand during the study period. In these patients, high transporter status was found to be a significant, independent predictor of death-censored technique failure (adjusted hazard ratio [AHR] 1.23; 95% confidence interval [CI] 1.02 to 1.49; P = 0.03) and mortality (AHR 1.34; 95% CI 1.05 to 1.79, P = 0.02) compared with low-average transport status. High-average transport class was also associated with mortality (AHR 1.21; 95% CI 1.00 to 1.48; P = 0.047) but not death-censored technique failure (AHR 1.04; 95% CI 0.90 to 1.21) compared with low-average transport status. When transport status was alternatively analyzed as a continuous variable, dialysate:plasma creatinine ratio at 4 h was independently predictive of both death-censored technique failure (AHR 1.07; 95% CI 1.01 to 1.295; P = 0.031) and death (AHR 1.09; 95% CI 1.01 to 1.373; P = 0.036 per 0.1 change in dialysate:plasma creatinine). Peritoneal transport rate is a highly significant risk factor for both mortality and death-censored technique failure in the Australian and New Zealand incident PD patient populations.

Peritoneal Transport Status Influence on Atherosclerosis/Inflammation in CAPD Patients

OBJECTIVE

Peritoneal transport status is one of the main determinants of dialysis adequacy and dialysis-related complications in end-stage renal disease patients receiving continuous ambulatory peritoneal dialysis (CAPD). In this study we aimed to investigate the relationship between peritoneal transport characteristics and known promoters of atherosclerosis in a group of patients receiving CAPD for a minimum of 36 months.

DESIGN AND PARTICIPANTS

We performed a cross-sectional study of a cohort of 84 patients with end-stage renal disease (37 men, 47 women; age, 44.0 +/- 15.7 years; dialysis duration, 40.3 +/- 8.1 months) who were receiving CAPD for minimum 36 months. Peritoneal transport characteristics were identified after a peritoneal equilibration test (PET) determined at the third month of CAPD using Dialysate/Plasma (D/P) reference values. Patients were classified according to one of four peritoneal transport types: high (H), high-average (HA), low-average (LA), and low (L). After PET, patients were grouped as high (H/HA group, n = 51) or low (L/LA group, n = 33) transporters. The patient groups' clinical and laboratory data before dialysis and after initiation of the CAPD were collected retrospectively. The patients' follow-up data were retrieved for the diagnosis of any atherosclerosis-related event after the initiation of CAPD. The following events were collected, including myocardial infarction, having been diagnosed as having coronary artery disease by angiography or myocardium scintigraphy, cerebrovascular accident, and development of clinically evident peripheral arterial disease.

RESULTS

A comparison of follow-up data revealed that the H/HA transport characteristic was associated with lower albumin (P < .01), higher C-reactive protein (CRP) (P < .0001) levels, and higher recombinant human erythropoietin (rHuEPO) needs (P < .001) when compared with the L/LA type. During follow-up, 28 patients showed an atherosclerosis-related event. Twenty-two of these were in the H/HA group (43.1%), whereas only six were in the L/LA group (18.1%, P < .01). Reanalysis of 18 patients with atherosclerosis-related events and high CRP levels (> 10 mg/L) showed that 15 were in the H/HA and 3 were in the L/LA group. Sixty-eight percent of the H/HA patients with atherosclerosis and 50% of the L/LA patients with an atherosclerotic event also had chronic inflammation (P < .001). A Pearson correlation analysis showed that there was a positive correlation between D/P creatinine levels and 36-month mean CRP levels (r = 0.608, P < .0001), and a negative correlation between D/P creatinine levels and 36-month mean albumin levels (r = -0.299, P < .005).

CONCLUSIONS

This study shows that the high transporter peritoneal membrane characteristic is a risk factor for inflammatory state in patients with end-stage renal disease. High-transporter patients are at an increased risk of atherosclerosis when compared with their low-transporter counterparts through chronic inflammation.