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

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

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

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

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.

Risk Factors Responsible for Ultrafiltration Failure in Early Stages of Peritoneal Dialysis

Objective

To define risk factors for ultrafiltration failure (UFF) during early stages of peritoneal dialysis (PD).

Design

Retrospective analysis of a group of patients whose peritoneal function was prospectively followed.

Setting

A tertiary-care public university hospital.

Patients

Nineteen of 90 long-term PD patients required a peritoneal resting period to recover UF capacity: 8 had this requirement before the third year on PD (early, EUFF group) and 11 had a late requirement (LUFF group). The remaining 71 patients, those with stable peritoneal function over time, constituted the control group.

Main Outcome Measures

Peritoneal UF capacity under standard conditions (monthly) and small solute peritoneal transport (yearly).

Results

None of the conditions appearing at the start of PD or during the observation period could be definitely identified as the cause of UFF. There were no differences in characteristics between the EUFF group and the other two groups, except for the higher prevalence of diabetes in the EUFF group. Residual renal function (RRF) declined in all three groups during the first 2 years, with rapid loss during the third year in the EUFF group. This rapid loss in RRF was coincident with UFF. Peritoneal solute and water transport at baseline was similar in the three groups. After 2 years on PD, individuals in the EUFF group showed a significantly lower UF and higher creatinine mass transfer coefficient values than those in the LUFF group. Diabetic patients in the control group showed remarkable stability in UF capacity over time. During the second year on PD, requirement for increases in dialysate glucose concentration was 3.4 ± 0.5% in the LUFF group, but as high as 25.5 ± 24.2% in the EUFF group. The accumulated days of active peritonitis (APID, days with cloudy effluent) were similar for the three groups after 1, 2, and 3 years on PD. Interestingly, diabetic patients in the control group showed an APID index significantly lower than the overall EUFF group. Diabetics in the control group also had significantly lower APID versus nondiabetics in the control group ( p = 0.016).

Conclusions

Our findings suggest that certain patients develop early UFF type I. Diabetic state and a higher glucose requirement to obtain adequate UF suggest that glucose on both sides of the peritoneal membrane could be responsible. The mechanisms for this higher requirement remain to be elucidated. The identification of a larger cohort of these early UFF patients should lead to a better exploration of the primary pathogenic mechanisms.

The Ratio of Extracellular Fluid to Total Body Water and Technique Survival in Peritoneal Dialysis Patients

Background

Patients receiving peritoneal dialysis experience a high technique failure rate and are often overhydrated. We examined whether an increased extracellular fluid volume (VECF) as a proportion of the total body water (VTBW) predicted technique survival (TS) in a prevalent patient cohort.

Methods

The VECFand VTBWwere estimated by multiple-frequency bioelectric impedance in 59 prevalent peritoneal dialysis patients (median time on dialysis 14 months). Demographic, biochemical (albumin, C-reactive protein, and ferritin), and anthropometric data, forearm muscle strength, nutritional score by three-point Subjective Global Assessment, residual renal function, dialysate-to-plasma (D/P) creatinine ratio, total weekly Kt/V urea, total creatinine clearance, normalized protein equivalent of nitrogen appearance, and midarm muscle circumference were also assessed. Technique survival was determined at 3 years, and significant predictors of TS were sought.

Results

In patient groups defined by falling above or below the median value for each parameter, only residual renal function ( p = 0.002), 24-hour ultrafiltrate volume ( p = 0.02), and VECF/ VTBWratio ( p = 0.05) were significant predictors of TS. Subjects with a higher than median VECF/ VTBWratio had a 3-year TS of 46%, compared to 78% in subjects with a lower than median value. In multivariate analysis, systolic blood pressure and VECF/ VTBWratio (both p < 0.05) were significant predictors of TS. C-reactive protein approached significance.

Conclusion

Increased ratio of extracellular fluid volume to total body water is associated with decreased TS in peritoneal dialysis.

Peritoneal Homocysteine Clearance is Inefficient in Peritoneal Dialysis Patients

Objectives

To investigate the degree and the determinants of peritoneal homocysteine (Hcy) clearance and to compare measured Hcy clearance with the Hcy clearance predicted based on molecular weight (MW).

Design

Cross-sectional observational analysis.

Setting

Tertiary care institutional dialysis center.

Patients

Sixty-five stable peritoneal dialysis (PD) patients.

Outcome Measures

Fasting blood and 24-hour pooled dialysate effluents were collected for determination of peritoneal clearances of Hcy (CpHcy), urea (CpUr), and creatinine (CpCr). The dialysate-to-plasma creatinine ratio at 4 hours (D/P Cr 4 h) and levels of red cell folate, B12, ferritin, and C-reactive protein (CRP) were measured concurrently. Observed CpHcy was compared with predicted clearance, based on Hcy plasma protein binding and the relative molecular weights of Hcy, urea, and creatinine.

Results

Plasma concentrations of Hcy averaged 24.6 ± 1.1 μmol/L and were elevated above the upper limit of normal in 59 (91%) patients. The mean dialysate concentration of Hcy was 2.9 ± 0.3 μmol/L, equating to a daily peritoneal elimination of 34.6 ± 3.6 μmol. Observed CpHcy was closely approximated by predicted CpHcy (8.7 ± 0.6 L/week/1.73 m2vs 9.0 ± 0.3 L/week/1.73 m2respectively, p = 0.55). Patients maintained on automated PD ( n = 5) had a CpHcy similar to that of patients treated with continuous ambulatory peritoneal dialysis (8.9 ± 1.0 L/week/1.73 m2vs 8.7 ± 0.6 L/week/1.73 m2, p = 0.92). The CpHcy was significantly correlated with C-reactive protein (CRP), D/P creatinine, CpUr, CpCr, and peritoneal protein loss, but not with plasma Hcy, albumin, B12, ferritin, age, dialysis duration, peritonitis episodes, or daily dialysate effluent volume. By multivariate analysis, the only variables that remained significant independent predictors of CpHcy were CRP and D/P Cr 4 h. High and high-average transporters had a higher CpHcy than low and low-average transporters (9.7 ± 0.8 L/week/1.73 m2vs 7.0 ± 0.7 L/week/1.73 m2, p < 0.05), despite comparably elevated plasma Hcy concentrations [25.2 ± 1.5 μmol/L vs 23.4 ± 1.6 μmol/L, p = nonsignificant (NS)].

Conclusions

Elevated plasma concentrations of Hcy are not efficiently reduced by PD. The relatively low peritoneal clearance of Hcy is largely accounted for by a high degree of plasma protein binding and is significantly influenced by peritoneal membrane permeability.

Peritoneal Dialysis in Asia: An External Perspective

There are almost 30 000 patients maintained on peritoneal dialysis (PD) in Asia, representing about 8% of all Asian dialysis patients. The largest numbers of PD patients are in Japan and China, but the highest PD penetration is in Hong Kong, Korea, and Singapore. Notable features of PD in Asia include the varying rates of use across the different countries. The reasons for this are reviewed here, with particular emphasis on the significance of whether dialysis providers are predominantly private or public. The excellent rates of both patient and technique survival in the richer Asian countries are also examined and interpreted in the context of recent data showing that Asian patients living in North America have generally superior survival on dialysis and better compliance with PD than their Caucasian counterparts. It is concluded that the healthier baseline health status in South East Asian patients, in particular, contributes to their impressive outcomes. The approach to both clearance and ultrafiltration is less aggressive in Asian countries than in the West. Studies looking at the relationship between clearance and clinical outcome in Asia are reviewed and it is concluded that the benefits of higher clearances have been harder to show than in North America because of the relatively better outcomes of the patients. The concern about sclerosing encapsulating peritonitis in Japan particularly is emphasized. The Hong Kong model of dialysis delivery with its high use of PD and the arguments for and against it are also reviewed.

The Cost Barrier to Peritoneal Dialysis in the Developing World—An Asian Perspective

Countries in Asia vary significantly in culture and socioeconomic status. Dialysis costs and reimbursement structures are significant factors in decisions about the rates and modalities of renal replacement therapy. From our survey of Asian nephrologists conducted in 2001, a number of observations can be made.

In many developing countries, the annual cost of continuous ambulatory peritoneal dialysis (CAPD) is greater than the per-capita gross national income (GNI). The median cost of a 2-L bag of peritoneal dialysis (PD) fluid is around US$5. The absolute cost of PD fluid among countries with significant differences in per-capita GNI actually varies very little. Thus, most renal failure patients can be expected to have problems accessing PD therapy in developing countries in Asia.

In countries with unequal reimbursement policies for PD versus hemodialysis, a lack of incentive to prescribe PD also exists. Automated PD is nearly non existent in many developing countries in Asia.

Some possible ways to reduce the cost barriers to PD in those countries include

• individual governments providing more public funding for treating dialysis patients;

• dialysate-producing companies reducing the cost of their products;

• physicians using appropriately smaller exchange volumes (3 x 2 L) in some Asian patients with smaller body sizes and with residual renal function; and

• reducing the complication rate for PD (for example, peritonitis) thereby reducing the costs required for treatment and hospitalization.

Acute Systemic Inflammation is Associated with an Increase in Peritoneal Solute Transport Rate in Chronic Peritoneal Dialysis Patients

Background

This study was performed to evaluate the effects of acute systemic inflammation on peritoneal solute transport rate (PSTR) in chronic peritoneal dialysis (CPD) patients.

Methods

A baseline standard peritoneal equilibration test (PET) was performed on each patient every 6 months, and blood concentration of high-sensitivity C-reactive protein (hs-CRP) was assayed every 2 months in our peritoneal dialysis clinic. Acute systemic inflammation was defined as a greater than 10-fold increase in hs-CRP concentration compared with baseline value, in the absence of peritonitis, and returning to baseline level in 2 months. In patients with acute systemic inflammation, PET and hs-CRP concentration assays were performed during inflammation and after recovery. Ten patients with acute systemic inflammation were enrolled in the inflammation group and 42 other patients served as controls.

Results

There were no significant changes in hs-CRP and dialysate-to-plasma ratio of creatinine (D/Pcreat) in the control group during the study period. In the inflammation group, median hs-CRP levels at baseline, during acute inflammation, and at recovery were 2.3 mg/L (range 0.3 – 4.5 mg/L), 39.2 mg/L (range 15.1 – 117.4 mg/L), and 3.7 mg/L (range 0.9 – 8.9 mg/L), respectively. Median D/Pcreat increased significantly from baseline (0.64; range 0.55 – 0.98) to time of acute inflammation (0.72; range 0.60 – 0.96) ( p < 0.05). The D/Pcreat at recovery was 0.67 (range 0.52 – 0.94), which decreased significantly from time of acute inflammation ( p < 0.05). There was no correlation between changes in log (hs-CRP) and changes in D/Pcreat.

Conclusion

We have shown here that acute systemic inflammation is associated with a temporary increase in PSTR in CPD patients.

Analysis of the Prevalence and Causes of Ultrafiltration Failure during Long-Term Peritoneal Dialysis: A Cross-Sectional Study

Background

Ultrafiltration failure (UFF) is a major complication of peritoneal dialysis (PD). It can occur at any stage of PD, but develops in time and is, therefore, especially important in long-term treatment. To investigate its prevalence and to identify possible causes, we performed a multicenter study in The Netherlands, where patients treated with PD for more than 4 years were studied using a peritoneal function test (standard peritoneal permeability analysis) with 3.86% glucose. UFF was defined as net UF < 400 mL after a 4-hour dwell.

Results

55 patients unselected for the presence or absence of UFF were analyzed. Mean age was 48 years (range 18 – 74 years); duration of PD ranged from 48 to 144 months (median 61 months); UFF was present in 20 patients (36%). Patients with and without UFF did not differ in age or duration of PD. Median values for patients with normal UF compared to patients with UFF were, for net UF 659 mL versus 120 mL ( p < 0.01), transcapillary UF rate 3.8 versus 2.1 mL/minute ( p < 0.01), effective lymphatic absorption 1.0 versus 1.6 mL/min ( p < 0.05), mass transfer area coefficient (MTAC) for creatinine 9.0 versus 12.9 mL/min ( p < 0.01), dialysate-to-plasma ratio (D/P) for creatinine 0.71 versus 0.86 ( p < 0.01), glucose absorption 60% versus 73% ( p < 0.01), maximum dip in D/P sodium (as a measure of free water transport) 0.109 versus 0.032 ( p < 0.01), and osmotic conductance to glucose 3.0 versus 2.1 μL/min/mmHg ( p < 0.05). As causes for UFF, high MTAC creatinine, defined as > 12.5 mL/min, or a glucose absorption > 72%, both reflecting a large vascular surface, a lymphatic absorption rate (LAR) of > 2.14 mL/min, and a decreased dip in D/P sodium of < 0.046 were identified. Most patients had a combination of causes (12 patients), whereas there was only a decreased dip in D/P sodium in 3 patients, only high MTAC creatinine in 1 patient, and only high LAR in 2 patients. We could not identify a cause in 2 patients. Both groups had similar clearances of serum proteins and peritoneal restriction coefficients. However, dialysate cancer antigen 125 concentrations, reflecting mesothelial cell mass, were lower in the UFF patients (2.79 vs 5.38 U/L).

Conclusion

The prevalence of UFF is high in long-term PD. It is caused mainly by a large vascular surface area and by impaired channel-mediated water transport. In addition, these patients also had signs of a reduced mesothelial cell mass, indicating damage of the peritoneum on both vascular and mesothelial sites.

Improving Outcome of Capd: Twenty-Five Years’ Experience in a Single Korean Center

Background

Continuous ambulatory peritoneal dialysis (CAPD) is an established treatment for end-stage renal disease (ESRD). We investigated the outcome of CAPD over a period of 25 years at our institution.

Methods

CAPD has been performed in 2301 patients in 25 years. After excluding patients with less than 3 months of follow-up and missing data, we evaluated 1656 patients who started peritoneal dialysis between November 1981 and December 2005. Data for sex, age, primary disease, co-morbidities, follow-up duration, cause of death, and cause of technique failure were collected. We also examined data for urea kinetic modeling (UKM), beginning in 1990, and peritonitis episodes, including causative organisms, starting in 1992.

Results

Compared to incident patients from 1981 – 1992, mean age and incidence of ESRD caused by diabetic nephropathy increased in patients from 1993 to 2005. Technique survival after 5 and 10 years was 71.9% and 48.1% respectively. Technique survival was significantly higher in patients who started CAPD after 1992 than in those who started before 1992. Peritonitis was the main reason for technique failure. Overall peritonitis rate was 0.38 episodes per patient-year, with a significant downward trend to 0.29 per patient-year over 10 years, corresponding to a decrease in gram-positive peritonitis. Patient survival after 5 and 10 years was 69.8% and 51.8% respectively. Patient survival improved significantly during 1992 – 2005 compared to 1981 – 1992 after adjustment for age, gender, diabetes, and cardiovascular comorbidities [hazard ratio (HR) 0.68, p < 0.01]. Subgroup analysis based on UKM revealed that dialysis adequacy did not affect patient survival. However, diabetes (HR 2.78, p < 0.001), older age (per 1 year: HR 1.06; p < 0.001), serum albumin level (per 1 g/dL: increase, HR 0.52; p < 0.05), and cardiovascular comorbidities (HR 2.32, p < 0.01) were identified as significant risk factors.

Conclusion

Technique survival has improved due partly to a decrease in peritonitis, which was attributed to a decrease in gram-positive peritonitis. Patient survival has also improved considering increases in aged patients and ESRD caused by diabetes. The mortality rate of CAPD is still high in older, diabetic, malnourished, and cardiovascular diseased patients. A more careful management of higher risk groups will be needed to improve the outcome of CAPD patients in the future.

Development and Validation of the Modified Charlson Comorbidity Index in Incident Peritoneal Dialysis Patients: A National Population-Based Approach

Background

The utility of applying the Charlson comorbidity index (CCI) to peritoneal dialysis (PD) patients is disputed because the relative weight of each comorbidity in PD patients may be different from those in other chronic diseases. We aimed to develop and validate a modified CCI in incident PD patients (mCCI-IPD) for better risk stratification and prediction of mortality.

Methods

The mCCI-IPD was developed using data from all Korean adult incident PD patients between 2005 and 2008 ( n = 7,606). Multivariate Cox regression was used to determine new weights for the individual comorbidities in the CCI. The prognostic performance of the mCCI-IPD was validated in an independent cohort ( n = 664) through c-statistics and continuous net reclassification improvement (cNRI).

Results

A total of 75.5% of the patients in the development cohort had 1 or more comorbidities. The Cox proportional hazards model provided reassigned severity weights for the 11 comorbidities that significantly predicted mortality. In the validation cohort, the CCI and mCCI-IPD scores were both correlated with survival and showed no differences in their c-statistics. However, multivariate analyses using cNRI revealed that the mCCI-IPD provided a 38.2% improvement in mortality risk assessment compared with the CCI (95% confidence interval [CI], 15.3 – 61.0; p < 0.001). These significant reclassification improvements were observed consistently in subjects with events (cNRIEvent, 28.2% [95% CI, 6.9 – 49.5; p = 0.009]) and without events (cNRINon-event, 10.0% [95% CI, 1.7 – 18.2; p = 0.019]).

Conclusions

Compared with the CCI, the mCCI-IPD showed better performance in mortality prediction for incident PD patients. Therefore, this tool may be used as a preferred index for statistical analysis and clinical decision-making.

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.

Impact of C-reactive protein and pulse pressure evaluated at the start of peritoneal dialysis on cardiovascular events in the course of treatment with peritoneal dialysis

BACKGROUND

Despite a reduced number of infectious complications, cardiovascular (CV) mortality remains unchanged in peritoneal dialysis (PD) patients. The aim of this study was to evaluate the effects of high-sensitivity C-reactive protein (hs-CRP) and pulse pressure (PP) at the start of PD on the development of CV events (CVEs) in these patients.

METHODS

The study population was comprised of 291 patients that started PD between January 2003 and June 2008 and were treated for more than 6 months. Baseline clinical, biochemical, and echocardiographic data, indices of dialysis adequacy, and peritoneal transport rate were reviewed retrospectively. The clinical outcome was the occurrence of a CVE.

RESULTS

Mean duration of follow-up was 28 (range 6 - 70) months. A CVE was observed in 33 patients (11.3%). The 1-, 3-, and 5-year cumulative incidences of CVEs were 4.0%, 13.7%, and 27.5%, respectively. Although multiple variables were correlated with the prevalence of a CVE in the univariate analysis, hs-CRP, PP, and comorbidity remained significant after adjustment: hs-CRP: odds ratio (OR) 4.09 (1.53 - 10.95), p = 0.005; PP: OR 2.79 (1.26 - 6.17), p = 0.012. PP and hs-CRP, which were not intercorrelated in our data, combined adversely to increase the incidence of CVEs. The incidence of CVEs increased with the number of risk factors, which included high hs-CRP, high PP, and the presence of comorbidity (no risk factor, 0%; 1 risk factor, 1.5%; 2 risk factors, 30.8%; 3 risk factors, 53.9%).

CONCLUSIONS

Our study suggests that measurements of hs-CRP and PP at the start of PD may be helpful in predicting the development of CVEs in the course of treatment with PD.

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.

Chronic systemic inflammation in dialysis patients: an update on causes and consequences

Despite marked improvements in dialysis technology during the last 20 years, the age-adjusted mortality rate in end-stage renal disease (ESRD) patients treated by dialysis is still unacceptably high and comparable to that of many cancer patients with metastases. The main cause of the increased mortality in ESRD patients is cardiovascular disease (CVD), which is twice as common and advances at twice the rate already in patients with early stages of chronic kidney disease as compared to the general population. Although traditional risk factors for CVD are common in dialysis patients, they can only in part explain the very high prevalence of CVD in this patient group. Recent evidence demonstrates that chronic inflammation, a non-traditional risk factor which is a commonly observed in dialysis patients, may cause progressive atherosclerotic CVD and malnutrition, itself an important risk factor for the development of CVD, by several pathogenetic mechanisms. The causes of inflammation in dialysis are multifactorial and include both dialysis-related and unrelated factors. While the long-term effects of chronic inflammation may be most important in the pathogenesis of CVD, the acute-phase reaction may also cause vascular damage by several pathogenic mechanisms. Indeed, it seems logical to speculate that suppression of the vicious cycle of malnutrition, inflammation, and atherosclerosis (MIA syndrome) in ESRD would improve survival and decrease co-morbidity in dialysis patients. As there are currently no established guidelines for the treatment of chronic inflammation in ESRD patients, more studies on the long-term effects of various anti-inflammatory treatment strategies on the nutritional and cardiovascular status, as well as outcome in this patient group, are clearly warranted and will be helpful in identifying precisely which pathways are most involved in the pathogenic process.

Dialysate Leukocytes, sICAM-1, Hyaluronan and IL-6: Predictors of Outcome of Peritonitis?

BACKGROUND/AIMS

Despite effective antibiotic therapy, peritonitis still remains a major problem in peritoneal dialysis (PD). The aim of the present study was to investigate changes of CRP, dialysate leukocytes and IL-6, hyaluronan (HA) and sICAM-1 in dialysate during and after peritonitis and their association to the outcome of peritonitis.

METHODS

Dialysate IL-6, HA and sICAM-1 were measured at the onset and on day 4, at the end of the treatment and 2 months after onset of peritonitis. Furthermore, CRP and dialysate leukocytes were measured on days 1-4.

RESULTS

All measured soluble factors were higher on the first and fourth day than at the end of the treatment. sICAM-1 and HA were lower at the end of the treatment in patients who later had a relapse/re-infection. IL-6 remained higher 2 months after clinically cured peritonitis. CRP and dialysate leukocytes were higher on day 4 in patients with poor outcome.

CONCLUSIONS

Peritonitis causes increased excretion of soluble factors. Low concentrations of sICAM-1 and HA at the end of the treatment were negative prognostic indicators. Higher IL-6 levels after peritonitis could be a sign of ongoing inflammation in the peritoneal membrane. Delayed decrease in CRP and dialysate leukocytes may indicate poor outcome.

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.

Changes of cytokine profiles during peritonitis in patients on continuous ambulatory peritoneal dialysis

Continuous ambulatory peritoneal dialysis (CAPD) has emerged as an important dialysis treatment modality worldwide. One of the major complications is bacterial peritonitis, which may result in subsequent technique failure because of loss of peritoneal clearance or peritoneal fibrosis. Bacterial peritonitis leads to the release of proinflammatory cytokines from resident and infiltrating cells in the peritoneal cavity. We studied 35 patients undergoing CAPD with acute bacterial peritonitis. All patients treated with antibiotics for 2 weeks after the clinical diagnosis of peritonitis had a good recovery. Peritoneal dialysate effluent (PDE) was collected on days 1, 3, 5, 10, 21, and 42 after the start of treatment. Cell populations were monitored by flow cytometry. PDE levels of interleukin-1beta (IL-1), IL-6, transforming growth factor-beta (TGF-beta), and basic fibroblast growth factor (FGF) were measured by enzyme-linked immunosorbent assay. Gene transcription of TGF-beta in macrophages from PDE was measured by quantitative polymerase chain reaction. Bacterial peritonitis was associated with a sharp increase in total cell and neutrophil counts (400-fold) in PDE up to 3 weeks after peritonitis despite clinical remission (P < 0.0001). There was an increased absolute number of macrophages during the first 3 weeks despite the reduced percentage of macrophages among total cells in PDE compared with noninfective PDE. There was a progressive increase in the percentage of mesothelial cells or dead cells in the total cell population in PDE over the entire 6-week period. PDE levels of IL-1, IL-6, TGF-beta, and FGF increased markedly on day 1 before their levels decreased gradually. PDE levels of these cytokines or growth factors were significantly greater than those in noninfective PDE (n = 76) throughout the study period (P < 0.01). Similarly, TGF-beta complementary DNA (cDNA) molecules per macrophage were significantly greater than those of macrophages in noninfective PDE throughout this period (P < 0.01). There was no significant correlation between PDE levels of TGF-beta and TGF-beta cDNA molecules per macrophage, suggesting that peritoneal macrophages are not the only source of TGF-beta in PDE. We conclude there is an active release of proinflammatory cytokines and sclerogenic growth factors through at least 6 weeks despite apparent clinical remission of peritonitis. The peritoneal cytokine networks after peritonitis may potentially affect the physiological properties of the peritoneal membrane.