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

Possible role of IL-6 and TIE2 gene polymorphisms in predicting the initial high transport status in patients with peritoneal dialysis: an observational study

OBJECTIVES

The aim of this study was to investigate the effect of interleukin (IL)-6 and TIE2 gene polymorphisms on baseline peritoneal transport property.

DESIGN

An observational study.

SETTING

Renji Hospital in Shanghai, China.

PARTICIPANTS

This study included 220 patients with continuous ambulatory peritoneal dialysis (PD).

OUTCOME MEASURES

Patients were divided into 2 groups based on the results of an initial peritoneal equilibration test performed within 3 months of starting PD therapy: group 1 consisted of low/low average transporters (n=123), and group 2 consisted of high/high average transporters (n=97). We genotyped TIE2 and IL-6 polymorphisms and analysed their effects on baseline transport status.

RESULTS

The genotype AT in IL-6 Rs13306435 and the genotype CC in TIE2 Rs639225 were both negatively associated with a higher initial peritoneal transport status (IL-6 Rs13306435: OR=0.408, 95% CI 0.227 to 0.736; TIE2 Rs639225: OR=0.188, 95% CI 0.044 to 0.806).

CONCLUSIONS

IL-6 and TIE2 polymorphisms are associated with baseline peritoneal transport property.

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

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

Pro-inflammatory cytokines: a possible relationship with dialytic adequacy and serum albumin in peritoneal dialysis patients

Background

Inflammation and serum albumin concentration are both important predictors of survival in patients treated with peritoneal dialysis (PD). Furthermore, systemic and local inflammatory mediators may induce structural and functional alterations in the peritoneal membrane, thus interfering with dialysis adequacy. PD adequacy is monitored primarily by indices of small solute clearance, such as Kt/V urea and weekly creatinine clearance (wCc). The aim of this study was to investigate the possible relationship between pro-inflammatory cytokines, such as interleukin-6 (IL-6) and interleukin-1β (IL-1β), and serum albumin and C-reactive protein (CRP). Moreover, the relationship between IL-6 and IL-1β and PD adequacy has been analysed.

Methods

We enrolled 46 stable PD patients undergoing maintenance PD for a minimum of 3 months. Plasma levels of serum albumin, high-sensitivity (hs)-CRP, IL-6 and IL-1β were measured in all patients. We used weekly Kt/V urea and wCc to monitor PD adequacy. Daily urine volume was measured in all patients.

Results

The median values of serum albumin, hs-CRP, IL-6 and IL-1β showed no significant differences between continuous ambulatory PD and automated PD patients. IL-6 levels showed a positive correlation with hs-CRP levels (P < 0.001) and a negative correlation with serum albumin concentration (P = 0.01). There was no statistically significant relationship between IL-1β and hs-CRP or serum albumin concentrations. Subsequently, PD patients were divided into two groups based on Kt/V urea value. PD patients with Kt/V ≤1.7 had significantly higher IL-6 levels compared with PD patients with Kt/V >1.7 (P = 0.015). No statistically significant relationship between IL-6 and wCc was observed. There was no significant difference in IL-1β levels between PD patients with Kt/V ≤1.7 and with Kt/V >1.7 [median (interquartile range) 0.82 (0.88–5.2) versus 1.82 (0.95–2.7)]. There was no significant difference in IL-6 and IL-1β levels in PD patients with and without residual diuresis (P = 0.32 and P = 0.77, respectively).

Conclusion

Our data suggest a possible relationship between serum IL-6 levels and serum albumin and hs-CRP in PD patients. Furthermore, IL-6 seems to be higher in patients with lower Kt/V, thus suggesting a possible use of this inflammatory biomarker in PD adequacy monitoring.

Predictors of Transfer to Home Hemodialysis after Peritoneal Dialysis Completion

♦

BACKGROUND

The aim of the present study was to evaluate the predictors of transfer to home hemodialysis (HHD) after peritoneal dialysis (PD) completion. ♦

METHODS

All Australian and New Zealand patients treated with PD on day 90 after initiation of renal replacement therapy between 2000 and 2012 were included. Completion of PD was defined by death, transplantation, or hemodialysis (HD) for 180 days or more. Patients were categorized as "transferred to HHD" if they initiated HHD fewer than 180 days after PD had ended. Multivariable logistic regression was used to evaluate predictors of transfer to HHD in a restricted cohort experiencing PD technique failure; a competing-risks analysis was used in the unrestricted cohort. ♦

RESULTS

Of 10 710 incident PD patients, 3752 died, 1549 underwent transplantation, and 2915 transferred to HD, among whom 156 (5.4%) started HHD. The positive predictors of transfer to HHD in the restricted cohort were male sex [odds ratio (OR): 2.81], obesity (OR: 2.20), and PD therapy duration (OR: 1.10 per year). Negative predictors included age (OR: 0.95 per year), infectious cause of technique failure (OR: 0.48), underweight (OR: 0.50), kidney disease resulting from hypertension (OR: 0.38) or diabetes (OR: 0.32), race being Maori (OR: 0.65) or Aboriginal and Torres Strait Islander (OR: 0.30). Comparable results were obtained with a competing-risks model. ♦

CONCLUSIONS

Transfer to HHD after completion of PD is rare and predicted by patient characteristics at baseline and at the time of PD end. Transition to HHD should be considered more often in patients using PD, especially when they fulfill the identified characteristics.

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

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

Peritoneal Equilibration Test and Patient Outcomes

BACKGROUND AND OBJECTIVES

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

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

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

RESULTS

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

CONCLUSIONS

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

Influence of peritoneal transport characteristics on nutritional status and clinical outcome in Chinese diabetic nephropathy patients on peritoneal dialysis

Background:

High peritoneal transport status was previously thought to be a poor prognostic factor in peritoneal dialysis (PD) patients. However, its effect on diabetic nephropathy PD patients is unclear in consideration of the adverse impact of diabetes itself. The purpose of this study was to investigate the influence of peritoneal transport characteristics on nutritional status and clinical outcome in diabetic nephropathy patients on PD.

Methods:

One hundred and two diabetic nephropathy patients on PD were enrolled in this observational cohort study. According to the initial peritoneal equilibration test result, patients were divided into two groups: Higher transport group (HT, including high and high average transport) and lower transport group (LT, including low and low-average transport). Demographic characteristics, biochemical data, dialysis adequacy, and nutritional status were evaluated. Clinical outcomes were compared. Risk factors for death-censored technique failure and mortality were analyzed.

Results:

Compared with LT group (n = 37), serum albumin was significantly lower and the incidence of malnutrition by subjective global assessment was significantly higher in HT group (n = 65) (P < 0.05). Kaplan–Meier analyses showed that death-censored technique failure and mortality were significantly increased in HT group compared with that in LT group. On multivariate Cox analyses, higher peritoneal transport status and lower residual renal function (RRF) were independent predictors of death-censored technique failure when adjusted for serum albumin and total weekly urea clearance (Kt/V). Independent predictors of mortality were advanced age, anemia, hypoalbuminemia, and lower RRF, but not higher peritoneal transport status.

Conclusions:

Higher peritoneal transport status has an adverse influence on nutrition for diabetic nephropathy patients on PD. Higher peritoneal transport status is a significant independent risk factor for death-censored technique failure, but not for mortality in diabetic nephropathy patients on PD.

Abdominal Obesity and Mortality in Continuous Ambulatory Peritoneal Dialysis Patients

Background

The relationship between abdominal obesity (AO) and mortality in peritoneal dialysis (PD) patients is controversial.

Methods

The prevalence of AO in 84 PD patients was assessed in a cross-section manner and followed up for 9 years at a single center. AO was defined as a waist circumference (WC) of more than 90 cm in males or more than 80 cm in females. The patients were classified as either with AO(AO group) or without AO(nAO group).

Results

The AO group was older, contained more diabetics, more females, and had higher Charlson comorbidity index (aCCI) scores, BMI, and triglyceride and lower serum creatinine than the non-AO subjects. The follow-up duration was 53.2±34.4 months. At the end of the follow-up, eighteen patients (21.4%) were dead; 9 died of cardiovascular causes. The five year survival rate was 40.8%. Kaplan-Meier analysis revealed that both all-cause and cardiovascular-cause mortalities were similar in the AO and nAO groups. Multivariate analysis revealed the presence of AO not to be an independent risk factor of all-cause and cardiovascular-cause mortality.

Conclusion

AO itself might not be a risk factor for mortality in PD patients. Nevertheless, further prospective studies with a large number of patients will be needed to prove this.

Predicting one-year mortality in peritoneal dialysis patients: an analysis of the China Peritoneal Dialysis Registry

This study aims to investigate basic clinical features of peritoneal dialysis (PD) patients, their prognostic risk factors, and to establish a prognostic model for predicting their one-year mortality. A national multi-center cohort study was performed. A total of 5,405 new PD cases from China Peritoneal Dialysis Registry in 2012 were enrolled in model group. All these patients had complete baseline data and were followed for one year. Demographic and clinical features of these patients were collected. Cox proportional hazards regression model was used to analyze prognostic risk factors and establish prognostic model. A validation group was established using 1,764 new PD cases between January 1, 2013 and July 1, 2013, and to verify accuracy of prognostic model. Results indicated that model group included 4,453 live PD cases and 371 dead cases. Multivariate survival analysis showed that diabetes mellitus (DM), residual glomerular filtration rate (rGFR), , SBP, Kt/V, high PET type and Alb were independently associated with one-year mortality. Model was statistically significant in both within-group verification and outside-group verification. In conclusion, DM, rGFR, SBP, Kt/V, high PET type and Alb were independent risk factors for short-term mortality in PD patients. Prognostic model established in this study accurately predicted risk of short-term death in PD patients.

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

Background

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

Methods

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

Results

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

Conclusions

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

Electronic supplementary material

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

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.

Increased dialysate MCP-1 is associated with cardiovascular mortality in peritoneal dialysis patients: a prospective observational study

BACKGROUND

The aim of this study was to investigate the association between the dialysate MCP-1 (dMCP-1) and systemic inflammatory and nutritional markers in peritoneal dialysis (PD) patients. In addition, we examined the prognostic value of dMCP-1 on all-cause or cardiovascular mortality in these patients.

METHODS

We prospectively followed 169 prevalent PD patients from April 1st 2008 to December 31st 2012. At baseline, dMCP-1 and serum biochemical parameters including high sensitivity CRP (hs-CRP) and albumin were checked. All-cause mortality and cause of death were evaluated during the follow-up period. Based on the median level of dMCP-1, patients were classified as either low or high dMCP-1 groups.

RESULTS

Mean age, hs-CRP, and D/Pcr ratio at 4 h were significantly higher, while serum albumin levels and %lean body mass (LBM) were significantly lower in the high dMCP-1 group. During the mean follow-up period of 47.7 months, all-cause mortality and cardiovascular mortality rate were significantly higher in the high dMCP-1 group (9.6 and 6.3 per 100 person-years, respectively) compared to the low dMCP-1 group (5.1 and 3.1 per 100 person-years, respectively; p = 0.021, 0.038). In multivariate Cox analysis, high dMCP-1 was a significant independent predictor of all-cause mortality (hazard ratio: 1.83, 95% confidence interval: 1.03-3.24, p = 0.039).

CONCLUSIONS

dMCP-1 levels are closely correlated with nutritional and systemic inflammatory markers in PD patients. In addition, increased dMCP-1 is significantly associated with higher all-cause and cardiovascular mortality. These findings suggest that local peritoneal inflammation could contribute to poor clinical outcomes in PD patients.

Higher Dialysate Matrix Metalloproteinase-2 Levels Are Associated with Peritoneal Membrane Dysfunction

♦

BACKGROUND

Peritoneal dialysis (PD) patients develop progressive and cumulative peritoneal injury with longer time spent on PD. The present study aimed to a) describe the trend of peritoneal injury biomarkers, matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1), in incident PD patients, b) to explore the capacity of dialysate MMP-2 to predict peritoneal solute transport rate (PSTR) and peritonitis, and c) to evaluate the influence of neutral pH, low glucose degradation product (GDP) PD solution on these outcomes. ♦

METHODS

The study included 178 participants from the balANZ trial who had at least 1 stored dialysate sample. Changes in PSTR and peritonitis were primary outcome measures, and the utility of MMP-2 in predicting these outcomes was analyzed using multilevel linear regression and multilevel Poisson regression, respectively. ♦

RESULTS

Significant linear increases in dialysate MMP-2 and TIMP-1 concentrations were observed (p < 0.001), but neither was affected by the type of PD solutions received (MMP-2: p = 0.07; TIMP-1: p = 0.63). An increase in PSTR from baseline was associated with higher levels of MMP-2 (p = 0.02), and the use of standard solutions over longer PD duration (p = 0.001). The risk of peritonitis was independently predicted by higher dialysate MMP-2 levels (incidence rate ratio [IRR] per ng/mL 1.01, 95% confidence interval [CI] 1.005 - 1.02, p = 0.002) and use of standard solutions (Biocompatible solution: IRR 0.45, 95% CI 0.24 - 0.85, p = 0.01). ♦

CONCLUSION

Dialysate MMP-2 and TIMP-1 concentrations increased with longer PD duration. Higher MMP-2 levels were associated with faster PSTR and future peritonitis risk. Administration of biocompatible solutions exerted no significant effect on dialysate levels of MMP-2 or TIMP-1, but did counteract the increase in PSTR and the risk of peritonitis associated with the use of standard PD solutions. This is the first longitudinal study to examine the clinical utility of MMP-2 as a predictor of patient-level outcomes.

Automated peritoneal dialysis prescriptions for enhancing sodium and fluid removal: a predictive analysis of optimized, patient-specific dwell times for the day period

BACKGROUND

Remaining edema-free is a challenge for many automated peritoneal dialysis (APD) patients, especially those with fast ("high") transport characteristics. Although increased use of peritoneal dialysis (PD) solutions with high glucose concentrations may improve volume control, frequent use of such solutions is undesirable.

METHODS

We used the 3-pore kinetic model to evaluate 4 alternative therapy prescriptions for the APD day exchange in anuric patients with high, high-average, and low-average transport characteristics. Four prescriptions were modeled: Therapy 1: Optimal, individualized dwell times with a dry period. Therapy 2: Use of a midday exchange. Therapy 3: Use of an icodextrin-containing dialysate during a 14-hour dwell. Therapy 4: Use of optimal, individualized dwell times, followed by an icodextrin dwell to complete the daytime period. The alternative therapies were compared with a reference standard therapy using glucose solution during a 14-hour dwell. The nighttime prescription was identical in all cases (10 L over 10 hours), and all glucose solutions contained 2.27% glucose. Net ultrafiltration (UF), sodium removal (NaR), total carbohydrate (CHO) absorption, and weekly urea Kt/V for a 24-hour period were computed and compared.

RESULTS

The UF and NaR were substantially higher with therapy 1 than with standard therapy (1034 mL vs 621 mL and 96 mmol vs 51 mmol respectively), without significant changes in CHO absorption or urea Kt/V. However, therapy 1 resulted in reduced β2-microglobulin clearance (0.74 mL/min vs 0.89 mL/min with standard therapy). Compared with therapy 1, therapy 2 improved UF and NaR (1062 mL vs 1034 mL and 99 mmol vs 96 mmol); however, that improvement is likely not clinically significant. Therapy 2 also resulted in a higher Kt/V (2.07 vs 1.72), but at the expense of higher glucose absorption (difference: 42 g). The UF and NaR were highest with a long icodextrin-containing daytime dwell either preceded by a short optimized dwell (1426 mL and 155 mmol) or without such a dwell (1327 mL and 148 mmol).

CONCLUSIONS

The 3-pore model predictions revealed that patient-specific optimal dwell times and regimens with a longer day dwell might provide improved UF and NaR options in APD patients with a variety of peritoneal membrane transport characteristics. In patients without access to icodextrin, therapy 1 might enhance UF and NaR and provide a short-term option to increase fluid removal. Although that approach may offer clinicians a therapeutic option for the overhydrated patient who requires increased UF in the short term, APD prescriptions including icodextrin provide a means to augment sodium and fluid removal. Data from clinical trials are needed to confirm the predictions from this study.

Intraperitoneal interleukin-6 levels predict peritoneal solute transport rate: a prospective cohort study

BACKGROUND

To evaluate the association of dialysate interleukin-6 (IL-6), a marker of ongoing peritoneal inflammation, with the alteration of peritoneal solute transport rate (PSTR) in continuous ambulatory peritoneal dialysis (CAPD) patients.

METHODS

Stable CAPD patients were enrolled in the present study. A total of 128 patients were analyzed in this prospective study. IL-6 concentration in the overnight effluent was determined and expressed as the IL-6 appearance rate (IL-6AR). Mass transfer area coefficients of creatinine (MTACcr) were measured at enrollment and 12 months later. Logistic regression was used to examine the association between IL-6AR and change in MTACcr.

RESULTS

Multivariable linear regression showed that historical glucose exposure was significantly associated with dialysate IL-6AR level [β = 0.008 (0.001-0.015), p = 0.021]. After 12 months, MTACcr was significantly increased [6.40 (4.70-8.75) vs. 7.14 (5.69-8.73) ml/min, p = 0.004], while ultrafiltration capacity decreased [4 h UF 340 (220-400) vs. 280 (180-380) ml, p = 0.006]. Compared to the patients with stable PSTR, the dialysate IL-6AR in patients with increasing PSTR was significantly higher [277.08 (247.45-349.53) vs. 263.18 (69.94-286.72) pg/min, p = 0.015]. Patients with increasing PSTR had lower residual renal function [0.79 (0-2.12) vs. 1.70 (0.39-3.38) ml/min, p = 0.006] and less urine output [225 (0-600) vs. 500 (125-900) ml/24 h, p = 0.014]. Logistic analysis showed that both high dialysate IL-6AR [OR 1.333 and 95% CI (1.024-1.735), p = 0.033] and low RRF [OR 0.831 and 95% CI (0.699-0.988), p = 0.036] were independent risk factors for increasing PSTR.

CONCLUSIONS

This prospective study suggests that intraperitoneal IL-6 is a predictor of increasing PSTR in peritoneal dialysis patients.

Clinical causes of inflammation in peritoneal dialysis patients

Inflammation at both systemic and local intraperitoneal levels commonly affects peritoneal dialysis (PD) patients. Interest in inflammatory markers as targets of therapeutic intervention has been considerable as they are recognised as predictors of poor clinical outcomes. However, prior to embarking on strategies to reduce inflammatory burden, it is of paramount importance to define the underlying processes that drive the chronic active inflammatory status. The present review aims to comprehensively describe clinical causes of inflammation in PD patients to which potential future strategies may be targeted.

Biocompatible dialysis fluids for peritoneal dialysis

BACKGROUND

The longevity of peritoneal dialysis (PD) is limited by high rates of technique failure, some of which stem from peritoneal membrane injury. 'Biocompatible' PD solutions have been developed to reduce damage to the peritoneal membrane.

OBJECTIVES

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

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (28 February 2013), through contact with the Trials Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE, and handsearching conference proceedings.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors extracted data on study quality and outcomes (including adverse effects). The authors contacted investigators to obtain missing information. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for categorical variables, and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous variables.

MAIN RESULTS

Thirty-six eligible studies (2719 patients) were identified: Neutral pH, lactate-buffered/bicarbonate (± lactate)-buffered, low GDP PD solution (24); icodextrin (12). Allocation methods and concealment were generally incompletely reported, and adequate in only ten studies (27.8%). Patients lost to follow-up ranged from 0% to 83.4%. Neutral pH, low GDP versus conventional glucose PD solutionBased on generally sub-optimal quality evidence, the use of neutral pH, low GDP PD solutions was associated with larger urine volumes at the end of the studies, up to three years of therapy duration (7 studies, 520 patients: MD 126.39 mL/d, 95% CI 26.73 to 226.05). Improved preservation of residual renal function was evident in studies with greater than 12 month follow-up (6 studies, 360 patients: SMD 0.31, 95% CI 0.10 to 0.52). There was no significant effect on peritonitis, technique failure or adverse events with the use of neutral pH, low GDP PD solutions. Glucose polymer (icodextrin) versus conventional glucose PD solutionThere was a significant reduction in episodes of uncontrolled fluid overload (2 studies, 100 patients: RR 0.30, 95% CI 0.15 to 0.59) and improvement in peritoneal ultrafiltration (4 studies, 102 patients, MD 448.54 mL/d, 95% CI 289.28 to 607.80) without compromising residual renal function (4 studies, 114 patients: SMD 0.12, 95% CI -0.26 to 0.49) or urine output (3 studies, 69 patients: MD -88.88 mL/d, 95% CI -356.88 to 179.12) with icodextrin use. A comparable incidence of adverse events with the icodextrin (four studies) was reported.

AUTHORS' CONCLUSIONS

Based on generally sub-optimal quality studies, use of neutral pH, low GDP PD solution led to greater urine output and higher residual renal function after use exceeded 12 months. Icodextrin prescription improved peritoneal ultrafiltration and mitigated uncontrolled fluid overload. There were no significant effects on peritonitis, technique survival, patient survival or harms identified with their use. Based on the best available evidence, the use of these 'biocompatible' PD solutions resulted in clinically relevant benefits without added risks of harm.

High-sensitivity C-reactive protein predicts mortality and technique failure in peritoneal dialysis patients

Introduction

An elevated level of serum C-reactive protein (CRP) is widely considered an indicator of an underlying inflammatory disease and a long-term prognostic predictor for dialysis patients. This cross-sectional cohort study was designed to assess the correlation between the level of high-sensitivity CRP (HS-CRP) and the outcome of peritoneal dialysis (PD) patients.

Methods

A total of 402 patients were stratified into 3 tertiles (lower, middle, upper) according to serum HS-CRP level and and followed up from October 2009 to September 2011. During follow-up, cardiovascular events, infection episodes, technique failure, and mortality rate were recorded.

Results

During the 24-month follow-up, 119 of 402 patients (29.6%) dropped out from PD, including 28 patients (7.0%) who died, 81 patients (20.1%) who switched to hemodialysis, and 10 patients (2.5%) who underwent kidney transplantation. The results of Kaplan–Meier analysis and log-rank test demonstrated a significant difference in the cumulative patient survival rate across the 3 tertiles (the lowest rate in upper tertile). On multivariate Cox regression analysis, only higher HS-CRP level, older age, the presence of diabetes mellitus (DM), lower serum albumin level, and the occurrence of cardiovascular events during follow-up were identified as independent predictors of mortality. Every 1 mg/L increase in HS-CRP level was independently predictive of a 1.4% increase in mortality. Multivariate Cox regression analysis also showed that higher HS-CRP level, the presence of DM, lower hemoglobin level, lower serum albumin level, higher dialysate/plasma creatinine ratio, and the occurrence of infective episodes and cardiovascular events during follow-up were independent predictors of technique failure.

Conclusions

The present study shows the importance of HS-CRP in the prediction of 2-year mortality and technique survival in PD patients independent of age, diabetes, hypoalbuminemia, and the occurrence of cardiovascular events.

Predictors and outcomes of transfers from peritoneal dialysis to hemodialysis

INTRODUCTION

Peritoneal dialysis (PD) patients are commonly required to transfer to hemodialysis (HD), however the literature describing the outcomes of such transfers is limited. The aim of our study was to describe the predictors of these transfers and their outcomes according to vascular access at the time of transfer.

METHODS

A retrospective cohort study using registry data of all adult patients commencing PD as their initial renal replacement therapy in Australia or New Zealand between 2004 - 2010 was performed. Follow-up was until 31 December 2010. Logistic regression models were constructed to determine possible predictors of transfer within both 6 and 12 months of PD commencement. Cox analysis and competing risks regression were used to determine the predictors of survival and transplantation post-transfer.

RESULTS

The analysis included 4,781 incident PD patients, of whom 1,699 transferred to HD during the study period. Logistic models did not identify any clinically useful predictors of transfer within 6 or 12 months (c-statistics 0.54 and 0.55 respectively). 67% of patients commenced HD with a central venous catheter (CVC). CVC use at transfer was associated with increased mortality (hazard ratio 1.37, 95% confidence interval (CI) 1.11 - 1.68, p = 0.003) and a borderline significant reduction in the incidence of transplantation (subhazard ratio 0.76, 95% CI 0.58 - 1.00, p = 0.05).

CONCLUSIONS

It is difficult to predict the transfer to HD for incident PD patients. PD patients who commence HD with a CVC have a higher risk of mortality and a lower likelihood of undergoing renal transplantation.

Dialysate interleukin-6 predicts increasing peritoneal solute transport rate in incident peritoneal dialysis patients

Background

Repeated exposure to peritoneal dialysis (PD) solutions contributes to cumulative intraperitoneal inflammation and peritoneal injury. The present study aimed to explore the capacity of dialysate interleukin-6(IL-6) to a) predict peritoneal membrane function and peritonitis in incident PD patients, and b) to evaluate the influence of neutral pH, low glucose degradation product (GDP) PD solution on dialysate IL-6 levels.

Methods

The study included 88 incident participants from the balANZ trial who had completed 24-months of follow-up. Change in peritoneal solute transport rate (PSTR) and peritonitis were primary outcome measures, and the utility of IL-6 and IL-6 appearance rate (IL-6 AR) in predicting these outcomes was analyzed using multilevel linear regression and Cox proportional hazards models, respectively. Sensitivity analyses were performed by analyzing outcomes in a peritonitis-free cohort (n = 56).

Results

Dialysate IL-6 concentration significantly increased from baseline to 24 months (mean difference 19.07 pg/mL; P < 0.001) but was not affected by the type of PD solution received (P = 0.68). An increase in PSTR from baseline was associated with higher levels of IL-6 (P = 0.004), the use of standard solutions (P = 0.005) and longer PD duration (P < 0.001). Baseline IL-6 level was not associated with a shorter time to first peritonitis (adjusted hazard ratio 1.00, 95% CI 0.99-1.00, P = 0.74). Analysis of IL-6 AR as well as sensitivity analyses in a peritonitis-free cohort yielded comparable results.

Conclusion

Dialysate IL-6 concentration increased with longer PD duration and was a significant, independent predictor of PSTR. The use of biocompatible PD solutions exerted no significant effect on dialysate IL-6 levels but did abrogate the increase in PSTR associated with standard PD solutions. This is the first study to examine the impact of biocompatible solutions on the utility of IL-6 in predicting PSTR and peritonitis.

Causes of death in peritoneal dialysis patients with different kidney diseases and comorbidities: a retrospective clinical analysis in a Chinese center

OBJECTIVES

The objective of the study is to identify and compare the different causes of death among peritoneal dialysis (PD) patients varying in baseline characteristics, including gender, age, primary diseases, and comorbidities and to assess risk factors for first-year death.

METHODS

The clinical data of 179 PD patients who were regularly followed up in our hospital and died between January 2006 and February 2011 were retrospectively reviewed.

RESULTS

Median age at PD catheter implantation was 73 years. The most common primary diseases leading to ESRD were diabetic nephropathy (DN; 26.3 %), chronic glomerulonephritis (CGN; 24.6 %), and hypertensive nephropathy (HN; 21.8 %). The main causes of death in the DN and CGN groups were infections (42.6 %) and cardiocerebrovascular accidents (34.1 %), respectively. Patients with systemic vasculitis (SV) had the highest mortality rate from infection (71.4 %). Cox regression model showed that, compared with patients with CGN, those who had primary disease of DN, renal amyloidosis, multiple myeloma, or vasculitis were at higher risk of first-year death. Cerebrovascular disease, chronic heart failure, and/or lower serum albumin at baseline were also risk factors for first-year death.

CONCLUSIONS

The main causes of death in PD patients with DN and CGN were infections and cardiocerebrovascular accidents, respectively. Risk factors for first-year death included the primary diseases, cerebrovascular diseases, chronic heart failure, and lower serum albumin at baseline.

TGF-β1 promotes lymphangiogenesis during peritoneal fibrosis

Peritoneal fibrosis (PF) causes ultrafiltration failure (UFF) and is a complicating factor in long-term peritoneal dialysis. Lymphatic reabsorption also may contribute to UFF, but little is known about lymphangiogenesis in patients with UFF and peritonitis. We studied the role of the lymphangiogenesis mediator vascular endothelial growth factor-C (VEGF-C) in human dialysate effluents, peritoneal tissues, and peritoneal mesothelial cells (HPMCs). Dialysate VEGF-C concentration correlated positively with the dialysate-to-plasma ratio of creatinine (D/P Cr) and the dialysate TGF-β1 concentration. Peritoneal tissue from patients with UFF expressed higher levels of VEGF-C, lymphatic endothelial hyaluronan receptor-1 (LYVE-1), and podoplanin mRNA and contained more lymphatic vessels than tissue from patients without UFF. Furthermore, mesothelial cell and macrophage expression of VEGF-C increased in the peritoneal membranes of patients with UFF and peritonitis. In cultured mesothelial cells, TGF-β1 upregulated the expression of VEGF-C mRNA and protein, and this upregulation was suppressed by a TGF-β type I receptor (TGFβR-I) inhibitor. TGF-β1-induced upregulation of VEGF-C mRNA expression in cultured HPMCs correlated with the D/P Cr of the patient from whom the HPMCs were derived (P<0.001). Moreover, treatment with a TGFβR-I inhibitor suppressed the enhanced lymphangiogenesis and VEGF-C expression associated with fibrosis in a rat model of PF. These results suggest that lymphangiogenesis associates with fibrosis through the TGF-β-VEGF-C pathway.

The impact of neutral-pH peritoneal dialysates with reduced glucose degradation products on clinical outcomes in peritoneal dialysis patients

Neutral-pH peritoneal dialysates, with reduced glucose degradation products (GDPs), have been developed to reduce peritoneal membrane damage. Here our review evaluated the impact of these solutions on clinical outcomes using data from The Cochrane CENTRAL Registry, MEDLINE, Embase, and reference lists for randomized trials of biocompatible solutions. Summary estimates of effect were obtained using a random-effects model of 20 eligible trials encompassing 1383 patients. The quality of studies was generally poor, such that 13 studies had greater than a 20% loss to follow-up and only 3 trials reported adequate concealment of allocation. Use of neutral-pH dialysates with reduced GDPs resulted in larger urine volumes (7 trials; 520 patients; mean difference 126 ml/day, 95% CI 27-226), improved residual renal function after 12 months (6 trials; 360 patients; standardized mean difference 0.31, 95% confidence interval 0.10-0.52), and a trend to reduced inflow pain (1 trial; 58 patients; relative risk 0.51, 95% CI 0.24-1.08). However, there was no significant effect on body weight, hospitalization, peritoneal solute transport rate, peritoneal small-solute clearance, peritonitis, technique failure, patient survival, or adverse events. No significant harms were identified. Thus, based on generally poor quality trials, the use of neutral-pH peritoneal dialysates with reduced GDPs resulted in greater urine volumes and residual renal function after 12 months, but without other clinical benefits. Larger, better-quality studies are needed for accurate evaluation of the impact of these newer dialysates on patient-level hard outcomes.

[Peritoneal dialysis from the beginnings up to today: which developments of the last decades were important?]

During the past years new developments in peritoneal dialysis (PD) technique have resulted in continuous improvement of patient outcome. The importance of salt and fluid balance, residual renal function and peritoneal glucose load are of increasing interest, whereas small solute clearances have lost importance. In patients with high peritoneal transport rates automated PD (APD) is indicated. However, APD can also be chosen as initial PD treatment since recent studies show comparable or even better survival as compared to continuous ambulatory PD patients. Alternative PD solutions improve peritoneal ultrafiltration (icodextrin), reduce peritoneal glucose load (amino acid solution, icodextrin) and protect the peritoneal membrane (solutions with low concentration of glucose degradation products). Infection risk can be reduced when using antibiotic creams, but resistances should be considered. Ongoing studies will clarify if non-antibiotic agents, e.g. medihoney, are effective in preventing PD-associated infections. Due to these improvements PD and hemodialysis have become equivalent treatments.

Higher peritoneal protein clearance as a risk factor for cardiovascular disease in peritoneal dialysis patient

Background and Aims

Although a number of studies have been published on peritoneal protein clearance (PrCl) and its association with patient outcomes, the results have been inconsistent. Therefore, the intent of this study was to evaluate the impact of PrCl on cardiovascular disease (CVD) and mortality in peritoneal dialysis (PD) patients.

Methods

This prospective observational study included a total of 540 incident patients who started PD at NHIC Ilsan Hospital, Korea from January 2000 to December 2009. Two different types of analyses such as intention-to-treat and as-treated were used.

Results

Correlation analyses revealed that PrCl was positively correlated with diabetes, pulse pressure, C–reactive protein (CRP) level, dialysate/plasma creatinine ratio (D/P cr) at 4 h, and peritoneal Kt/V urea. PrCl was inversely correlated with serum albumin and triglyceride levels. On multivariate analysis, serum albumin, pulse pressure, D/P cr at 4 h, and peritoneal Kt/V urea were found to be independent determinants of PrCl. A total of 129 (23.9%) patients in intention-to-treat analysis and 117 (21.7%) patients in as-treated analysis developed new cardiovascular events. Time to occurrence of cardiovascular event was significantly longer in patients with a value of PrCl below the median (89.4 ml/day). In multivariate analysis, older age, presence of diabetes or previous CVD, and higher PrCl were independent predictors of cardiovascular events. Patients above the median value of PrCl had a significantly lower rate of survival than those below the median. However, a higher PrCl was not associated with increased mortality in multivariate Cox analysis.

Conclusions

A higher PrCl is a risk for occurrence of cardiovascular event, but not mortality in PD patients. Large randomized clinical trials are warranted to confirm this finding.

Biocompatible peritoneal dialysis fluids: clinical outcomes

Peritoneal dialysis (PD) is a preferred home dialysis modality and has a number of added advantages including improved initial patient survival and cost effectiveness over haemodialysis. Despite these benefits, uptake of PD remains relatively low, especially in developed countries. Wider implementation of PD is compromised by higher technique failure from infections (e.g., PD peritonitis) and ultrafiltration failure. These are inevitable consequences of peritoneal injury, which is thought to result primarily from continuous exposure to PD fluids that are characterised by their "unphysiologic" composition. In order to overcome these barriers, a number of more biocompatible PD fluids, with neutral pH, low glucose degradation product content, and bicarbonate buffer have been manufactured over the past two decades. Several preclinical studies have demonstrated their benefit in terms of improvement in host cell defence, peritoneal membrane integrity, and cytokine profile. This paper aims to review randomised controlled trials assessing the use of biocompatible PD fluids and their effect on clinical outcomes.

Clinical outcomes of peritoneal dialysis patients transferred from hemodialysis: a matched case-control study

OBJECTIVE

Our study aimed to evaluate clinical outcomes of patients transferred to peritoneal dialysis (PD) because of complications related to hemodialysis (HD). ♢

METHODS

In a 1:2 matched case-control study, we compared patient and technique survival between patients initially treated with HD for at least 3 months and then transferred to PD (transfer group) and patients started on and continuing with PD (no-transfer group). ♢

RESULTS

All baseline characteristics except for initial residual urinary output were comparable between the groups. Compared with patients in the transfer group, patients in the no-transfer group had a higher initial daily residual urinary output [850 mL (range: 600 - 1250 mL) vs 0 mL (range: 0 - 775 mL/d), p = 0.000]. The main reasons for transfer to PD were vascular access problems and cardiovascular disease. Patient survival and technique failure rates did not significantly differ between the groups (p > 0.05). The 1-, 3-, and 5-year patient survival rates were 80.0%, 53.7%, and 27.6% in the transfer group and 89.7%, 60.2%, and 43.1% in the no-transfer group. Age (per 10 years) and serum albumin were independent risk factors for long-term survival in PD patients. Relative risk of either death or technique failure was not significantly increased in patients transferred from HD. ♢

CONCLUSIONS

Patients who transferred to PD after failing HD had outcomes on PD similar to those for patients who started with and were maintained on PD. Age (per 10 years) and serum albumin were independent risk factors for long-term survival in PD patients.

Nutrition in patients on peritoneal dialysis

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

Effluent free radicals are associated with residual renal function and predict technique failure in peritoneal dialysis patients

OBJECTIVE

Residual renal function (RRF) is associated with low oxidative stress in peritoneal dialysis (PD). In the present study, we investigated the relationship between the impact of oxidative stress on RRF and patient outcomes during PD.

METHODS

Levels of free radicals (FRs) in effluent from the overnight dwell in 45 outpatients were determined by electron spin resonance spectrometry. The FR levels, clinical parameters, and the level of 8-hydroxy-2'-deoxyguanosine were evaluated at study start. The effects of effluent FR level on technique and patient survival were analyzed in a prospective cohort followed for 24 months.

RESULTS

Levels of effluent FRs showed significant negative correlations with daily urine volume and residual renal Kt/V, and positive correlations with plasma β(2)-microglobulin and effluent 8-hydroxy-2'-deoxyguanosine. A highly significant difference in technique survival (p < 0.05), but not patient survival, was observed for patients grouped by effluent FR quartile. The effluent FR level was independently associated with technique failure after adjusting for patient age, history of cardiovascular disease, and presence of diabetes mellitus (p < 0.001). The level of effluent FRs was associated with death-censored technique failure in both univariate (p < 0.001) and multivariate (p < 0.01) hazard models. Compared with patients remaining on PD, those withdrawn from the modality had significantly higher levels of effluent FRs (p < 0.005).

CONCLUSIONS

Elevated effluent FRs are associated with RRF and technique failure in stable PD patients. These findings highlight the importance of oxidative stress as an unfavorable prognostic factor in PD and emphasize that steps should be taken to minimize oxidative stress in these patients.

High rates of mortality and technique failure in peritoneal dialysis patients after critical illness

INTRODUCTION

Little is known regarding the causes and outcomes of peritoneal dialysis (PD) patients admitted to the intensive care unit (ICU). We explored the outcomes of technique failure and mortality in a cohort of PD patients admitted to the ICU.

METHODS

Using a provincial database of 990 incident PD patients followed from January 1997 to June 2009, we identified 90 (9%) who were admitted to the ICU. Parametric and nonparametric tests were used as appropriate to determine differences in baseline characteristics. The Cox proportional hazards and competing risk methods were used to investigate associations.

RESULTS

Compared with other patients, those admitted to the ICU had been on PD longer (p < 0.0001) and were more often on continuous ambulatory PD (74.2% vs 25.8%, p = 0.016). Cardiac problems were the most common admitting diagnosis (50%), followed by sepsis (23%), with peritonitis accounting for 69% of the sepsis admissions. The 1-year mortality was 53.3%, with 12% alive and converted to hemodialysis, and one third remaining alive on PD. In multivariate Cox modeling, age [hazard ratio (HR): 1.01; 95% confidence interval (CI): 0.99 to 1.03], white blood cell count (HR: 1.02; 95% CI: 1.00 to 1.04), temperature (HR: 0.75; 95% CI: 0.61 to 0.92), and peritonitis (1.64; 95% CI: 1.21 to 2.22) at admission to the ICU were associated with the composite outcome of technique failure or death. In a competing risk analysis, the risk for death was 30%, and for technique failure, 36% at 1 year.

CONCLUSIONS

Patients on PD have high rates of death and technique failure after admission to the ICU.

Low-protein diet supplemented with keto acids is associated with suppression of small-solute peritoneal transport rate in peritoneal dialysis patients

Objective. We investigate whether low-protein diet would show benefits in suppressing peritoneal transport rate in peritoneal dialysis (PD) patients. Methods. This is a supplemented analysis of our previously published trial, which randomized 60 PD patients to receive low- (LP: dietary protein intake of 0.6-0.8 g/kg/d), keto-acid-supplemented low- (sLP: 0.6-0.8 g/kg/d with 0.12 g/kg/d of keto acids), or high- (HP: 1.0-1.2 g/kg/d) protein diet and lasted for one year. In this study, the variations of peritoneal transport rate were assessed. Results. While baseline D/P(cr) (dialysate-to-plasma concentration ratio for creatinine at 4 hour) and D/D0(glu) (dialysate glucose at 4 hour to baseline dialysate glucose concentration ratio) were similar, D/P(cr) in group sLP was lower, and D/D0(glu) was higher than those in the other two groups (P < 0.05) at 12th month. D/D0(glu) increased (P < 0.05), and D/P(cr) tended to decrease, (P = 0.071) in group sLP. Conclusions. Low-protein diet with keto acids may benefit PD patients by maintaining peritoneum at a lower transport rate.

Effects of comorbid and demographic factors on dialysis modality choice and related patient survival in Europe

BACKGROUND

The mean age of patients starting dialysis increased over the years, as has the proportion of patients with diabetes mellitus, ischaemic heart disease, peripheral vascular disease (PVD), cerebrovascular disease (CD) and malignancy. We assessed dialysis modality choice within subgroups of patients with these comorbidities and in different age categories and subsequently evaluated the association between modality choice and patient survival in these subgroups.

METHODS

Seven European renal registries participating in the ERA-EDTA Registry provided data from 15,828 incident peritoneal dialysis (PD) and haemodialysis (HD) patients (1998-2006) with available comorbidity data. The likelihood to receive PD rather than HD was assessed with logistic regression and 3-year survival on PD versus HD was evaluated using Cox regression.

RESULTS

Besides large international variations in the likelihood to receive PD, we found that elderly patients and patients with PVD, CD, malignancy and multiple comorbidities were significantly less likely to receive PD than HD. Overall patients starting on PD had survival benefits [adjusted hazard ratio (HR(adj)) 0.82 (0.75-0.90)], especially patients without comorbidity [HR(adj) 0.65 (0.53-0.80)] or those with malignancy [HR(adj) 0.73 (0.56-0.94)]. In males, survival benefits of PD were independent of diabetic status. Conversely, diabetic females tended to have increased mortality risk on PD [HR(adj) 1.16 (0.93-1.44)], especially if they were >70 years [HR(adj) 1.55 (1.15-2.08)].

CONCLUSIONS

In general, modality choice was consistent with expected survival. However, elderly patients, non-diabetic patients and those with malignancy were less likely to receive PD, even though they had decreased mortality risk on PD. Also, although a survival benefit of PD was found for male patients without comorbidity, HD was just as likely to be the chosen dialysis modality as was PD for these 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.

Peritoneal albumin and protein losses do not predict outcome in peritoneal dialysis patients

BACKGROUND AND OBJECTIVES

Peritoneal clearance of albumin-unlike the transport of small molecules-is defined by both vascular surface area and size-selective permeability. Few studies have supported a positive correlation between peritoneal albumin loss and mortality. The aim of this study was to investigate whether baseline peritoneal loss and clearance of albumin and other proteins is a risk factor of death in peritoneal dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

All incident peritoneal dialysis patients in our center during the last 15 years were included. Mass-transfer area coefficient of creatinine and peritoneal clearances of albumin, β₂-microglobulin, α₂-macroglobulin, and immunoglobulin G were calculated during a standard peritoneal permeability analysis. The total amount of albumin loss in the dialysate was also calculated. Overall mortality was studied with an intention-to-treat analysis.

RESULTS

Two hundred fifty-seven patients were included. High baseline albumin clearance was associated with fast transport status, the presence of peripheral arterial disease, and a high comorbidity index, whereas C-reactive protein levels did not differ from the patients with low albumin clearance. Age, high comorbidity score, C-reactive protein levels >10 mg/L, and a low serum albumin were associated with mortality. Peritoneal albumin clearances and albumin loss were not associated with death in crude and adjusted analysis. Similarly, peritoneal clearances of immunoglobulin G, α₂-macroglobulin, and β₂-microglobulin were not determinants of survival.

CONCLUSIONS

Baseline peritoneal albumin and protein clearances are associated with signs of comorbidity, but this does not have a measurable effect on patient survival.

Patient and physician predictors of peritoneal dialysis technique failure: a population based, retrospective cohort study

BACKGROUND

The use of peritoneal dialysis (PD) has been declining over the past decade in Canada, and high technique failure rates have been implicated. Studies have examined clinical risk factors for PD technique failure, but few studies have addressed sociodemographic factors driving technique failure. There are no studies examining the effect of physician factors on technique failure.

METHODS

We conducted a retrospective cohort study using Ontario healthcare databases from 1 April 1995 to 31 March 2005 to examine the effects of patient sociodemographic and physician characteristics on PD technique failure. The primary outcome was time to technique failure. Secondary outcomes included the proportion of patients experiencing technique failure during the first year and the proportion of patients experiencing death during the study period. A competing risks analysis was applied to the Cox proportional hazards model to determine the predictors of technique failure, death, and kidney transplantation.

RESULTS

In 5162 incident PD patients, the probability of technique success and patient survival at 5 years was 58.2% and 46.9% respectively. Of patients failing PD, 43.5% failed during the first year of treatment. Statistically significant predictors of technique failure included increasing age [hazard ratio (HR) 1.02], diabetes mellitus (HR 1.32), lower neighborhood education level (HR 2.93), and receiving transient (≤ 3 months) hemodialysis before starting PD (HR 1.24). Predictors of patient death included increasing age (HR 1.05), diabetes mellitus (HR 1.44), coronary artery disease (HR 1.26), congestive heart failure (HR 1.58), and late referral to the nephrologist (HR 1.27). Distance from treating dialysis center and residing in a rural area did not impact the risk of technique failure or death. Male physician gender increased the risk of technique failure (HR 1.31). Increased PD patient volume decreased the risk of technique failure (HR 0.98). None of the physician factors were predictors of patient death.

CONCLUSION

These findings support the need for implementing strategies to reduce technique failure, which could include increasing educational resources for patients initiating PD, aggressive risk factor modification in patients with multiple comorbidities, and increasing physician awareness regarding the detrimental outcomes associated with late referral and late PD start.

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.

Adverse outcomes among Aboriginal patients receiving peritoneal dialysis

BACKGROUND

The Aboriginal population in Canada experiences high rates of end-stage renal disease and need for dialytic therapies. Our objective was to examine rates of mortality, technique failure and peritonitis among adult aboriginal patients receiving peritoneal dialysis in the province of Manitoba. We also aimed to explore whether differences in these rates may be accounted for by location of residence (i.e., urban versus rural).

METHODS

We included all adult patients residing in the province of Manitoba who received peritoneal dialysis during the period from 1997-2007 (n = 727). We extracted data from a local administrative database and from the Canadian Organ Replacement Registry and the Peritonitis Organism Exit-sites/Tunnel infections (POET) database. We used Cox and logistic regression models to determine the relationship between outcomes and Aboriginal ethnicity. We performed Kaplan-Meier analyses to examine the relationship between outcomes and urban (i.e., 50 km or less from the primary dialysis centre in Winnipeg) versus rural (i.e., more than 50 km from the centre) residency among patients who were aboriginal.

RESULTS

One hundred sixty-one Aboriginal and 566 non-Aboriginal patients were included in the analyses. Adjusted hazard ratios for mortality (HR 1.476, CI 1.073-2.030) and adjusted time to peritonitis (HR 1.785, CI 1.352-2.357) were significantly higher among Aboriginal patients than among non-Aboriginal patients. We found no significant differences in mortality, technique failure or peritonitis between urban- or rural-residing Aboriginal patients.

INTERPRETATION

Compared with non-Aboriginal patients receiving peritoneal dialysis, Aboriginal patients receiving peritoneal dialysis had higher mortality and faster time to peritonitis independent of comorbidities and demographic characteristics. This effect was not influenced by place of residence, whether rural or urban.

The Effect of Weather on Peritoneal Dialysis (PD) Prescription: Seasonal Variation in PD Dialysate Utilization

♦ Background

There have been no reports on peritoneal dialysis (PD) solution utilization since this treatment was developed in the 1920s. The aim of the present investigation was to investigate if weather affects PD prescription.

♦ Study Design and Methods

This 10-year observational study used the Taiwan National Health Insurance Research Database. Setting and Participants: Claims for different concentrate PD dialysate were analyzed monthly. 2.5% and 4.25% PD solutes were defined as hypertonic solutions. Predictor: Monthly outdoor mean temperature. Outcome and Measurement: The relationship between monthly mean of PD dialysate utilization and monthly outdoor temperature was analyzed by linear regression. Monthly mean PD dialysate utilization amount in 4 quarters was analyzed by ANOVA.

♦ Results

During the 10-year study period, a clear seasonal variation in PD dialysate was observed. This seasonal variation was present regardless of age, gender, and the presence of hypertension, diabetes, and dyslipidemia. Monthly mean temperature was positively correlated to 1.5% dialysate utilization amount ( r = 0.559, p < 0.001) and negatively correlated to 2.5% ( r = –0.533, p < 0.001) and 4.25% ( r= –0.410, p < 0.001) dialysate utilization amount. In longitudinal follow-up, hypertonic PD fluid utilization was higher in diabetic patients than in nondiabetic patients from the beginning of treatment. Thereafter, it increased rapidly and reached a plateau within 1 year. Limitations: Analysis of ultrafiltration amount, blood pressure, and body weight was unfeasible due to the nature of the database.

♦ Conclusions

The utilization of differential strengths of PD solutions has a seasonal cyclic pattern, with more hypertonic PD solution utilized in winter and more hypotonic PD solution in summer.

Strategies for improving long-term survival in peritoneal dialysis patients

The incidence and prevalence of ESRD in the United States continues to increase. Currently there are over 26,000 patients maintained on peritoneal dialysis. Mortality rates have fallen over the past several years, but long-term survival remains poor, with only 11% of peritoneal dialysis patients surviving past 10 years. Cardiovascular disease accounts for most deaths, and dialysis patients have many traditional and nontraditional cardiovascular risk factors. Lowering of these risk factors has not resulted in reduced cardiovascular morbidity and mortality in dialysis patients. Maneuvers to improve long-term peritoneal dialysis patient survival must therefore focus on modifiable risk factors including residual renal function, peritoneal membrane integrity, rate of infections, and peritoneal dialysis center size. This article reviews strategies for preserving residual renal function and peritoneal membrane integrity as well as strategies for reducing the rate of infections to enhance long-term survival in peritoneal dialysis patients.

Outcome and risk factors for mortality in pediatric peritoneal dialysis

BACKGROUND

The mortality rate among children requiring renal replacement therapy is higher than in children without end-stage renal disease (ESRD). Some factors, such as hypoalbuminemia, high peritoneal transport rate, age, malnutrition, cardiovascular disease, and recurrent peritonitis, appear to be associated with lower survival in adult peritoneal dialysis patients. Data regarding risk factors of mortality in children with continuous ambulatory peritoneal dialysis (CAPD) are limited. The aims of this study were to analyze the clinical characteristics of patients and investigate if routinely used laboratory and clinical variables are independent risk factors for mortality in children on CAPD.

METHODS

We performed a retrospective chart analysis of pediatric ESRD patients on CAPD between January 1997 and September 2008. 29 patients undergoing CAPD for more than 3 months were enrolled. An analysis was performed on clinical and biochemical variables for survivors and nonsurvivors to identify potential risk factors for mortality.

RESULTS

Mean age was 12.18 +/- 4.57 years. During the follow-up period, 8 patients transferred to hemodialysis and 13 patients received deceased donor renal transplantation. By the end of the study, 5 patients had died. Actuarial survival rate at 2 and 5 years was 96.55% and 91.19% respectively. The major complication during therapy was peritonitis (1 episode/57.79 patient-months). In the univariate analysis, younger age at initiation of dialysis, presence of comorbid disease, higher peritoneal transport rate, increased protein losses through peritoneal dialysis, high total daily protein loss, hypoalbuminemia, and hypophosphatemia were variables associated with mortality in pediatric CAPD patients. However, in the multivariate analysis, only low serum albumin (b = -2.089, p = 0.006; hazard ratio 8.06, 95% confidence interval 0.028 - 0.546) was independently associated with mortality.

CONCLUSION

Mortality was low in our pediatric patients receiving CAPD. Hypoalbuminemia showed a significant association with death in CAPD patients.

Impact of peritoneal transport characteristics on cardiac function in paediatric peritoneal dialysis patients: a Turkish Pediatric Peritoneal Dialysis Study Group (TUPEPD) report

BACKGROUND

The peritoneal equilibration test (PET) is recommended in paediatric peritoneal dialysis (PD) patients to assist prescription management. Despite contradictory reports, high transporter status is associated with reduced survival rate in adults. Since cardiac disease is one of the main causes of mortality in paediatric PD patients, we aimed to evaluate whether transport features have any effect on biochemical data and cardiac function in this group.

METHODS

One hundred and ten PD patients (13 +/- 5 years, PD vintage: 31 +/- 27 months) were enrolled into the study. Four-hour dialysate/plasma creatinine ratio was used for differentiating PET groups. Thirty-eight patients were high transporters, 29 were high-average transporters and 43 were low-average/low transporters. Echocardiography was performed in all subjects.

RESULTS

Age, PD vintage, dialysate glucose concentration, ultrafiltration volume, urine volume and blood pressure levels were similar in all PET groups. No biochemical or echocardiographic data (ejection fraction, fractional shortening, left ventricular mass index, myocardial performance index, power Doppler E/tissue Doppler E ratio reflecting diastolic function) were different among PET groups except lower albumin (P = 0.025) levels in high transporters and higher high-sensitivity C-reactive protein (P = 0.026) levels in high and high-average transporters compared to other transport groups.

CONCLUSIONS

Cardiac structural and functional abnormalities are highly prevalent among paediatric PD patients. Transport rates did not have a significant effect on biochemical parameters or cardiac structural/functional parameters. It might be suggested that being a high transporter does not provide a disadvantage in terms of atherogenic tendency and cardiac disease in paediatric PD patients. Oligoanuria, anaemia and hypertension were independent predictors of cardiac disease.

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.