Definition and risk factors of rapidly declining residual renal function in peritoneal dialysis: an observational study

Prognostic and Diagnostic Value of Endocan in Kidney Diseases

Endocan, previously called endothelial cell-specific molecule-1, is a soluble proteoglycan that is predominantly expressed in vascular endothelial cells of the lungs and kidneys. It is upregulated by proinflammatory cytokines and plays a critical role in inflammatory, proliferative, and neovascularization processes. The utility of endocan as a biomarker in a wide spectrum of diseases is being increasingly acknowledged. In this review, we summarize the current evidence concerning the role of endocan in kidney diseases, with emphasis on its prognostic and diagnostic value. It seems that the determination of plasma endocan levels may provide useful prognostic information in many types of renal failure such as chronic kidney disease, IgA nephropathy, and diabetic nephropathy. Endocan could additionally improve the early diagnostic evaluation of acute kidney disease, chronic renal allograft injury, and acute rejection after kidney transplantation, thus contributing to endothelial cell injury monitoring in a timely manner.

Zero-contrast percutaneous coronary interventions to preserve kidney function in patients with severe renal impairment and hemodialysis subjects

INTRODUCTION

Zero-contrast percutaneous coronary intervention (zero-PCI) is a new method for prevention of contrast-induced acute kidney injury (AKI) in patients with chronic kidney disease (CKD). However, evidence for its feasibility, safety and clinical utility is limited to reports of single cases or series of patients.

AIM

To present outcomes of zero-PCI in patients with severe CKD, including hemodialysis subjects, who were treated with this procedure in order to preserve their renal function.

MATERIAL AND METHODS

Twenty-nine zero-PCIs were performed, mostly as a staged procedure, in 20 patients with advanced CKD. In this group, 4 patients were treated with hemodialysis but presented preserved residual renal function. The estimated median risk for contrast-induced AKI in non-dialysis patients was 26% (26-57%).

RESULTS

Zero-PCI was feasible in each intended patient, including those with complex left main stenosis or lesion within a saphenous vein graft, and there was no specific complication associated with this technique. After the procedure, the factual AKI prevalence was 10% and no patient required renal replacement therapy. Three of 4 hemodialysis patients preserved their residual renal function. During the median follow-up of 3.2 (1.2-5.3) months no patient experienced an acute coronary event or required revascularization.

CONCLUSIONS

Zero-PCI is a safe and promising method to preserve renal function in patients with CKD and hemodialysis patients. Such an approach is feasible even in complex coronary lesions and yields good clinical outcomes in mid-term observation.

Serum Endocan as a Predictive Marker for Decreased Urine Volume in Peritoneal Dialysis Patients

Background

Endocan is expressed in vascular endothelial cells, and its expression is enhanced following endothelial injury via inflammatory cytokines. Subsequently, endocan is secreted into the circulation. Thus, serum endocan levels are considered a marker of endothelial injury. However, to the best of our knowledge, no data on the serum endocan levels in peritoneal dialysis (PD) patients are available.

Material/Methods

This study included 21 PD patients who underwent peritoneal equilibration test (PET) more than once between 2011 and 2015. Serum samples were collected from each patient, and the 24-h urine volume was measured at the time of PET. Serum endocan levels were measured using enzyme-linked immunosorbent assay (ELISA) at the time of the first PET, and their relationship with clinical data or the extent of urine volume decline (mL/year) was analyzed retrospectively.

Results

Serum endocan levels were positively correlated with proteinuria level, serum creatinine level, serum tumor necrosis factor (TNF)-α level, β₂-microglobulin level, and PD drainage volume, but not with urine volume at baseline. The extent of decline in urine volume was significantly associated with serum endocan level, proteinuria level, serum creatinine level, and serum TNF-α level at baseline in a simple linear regression analysis. Moreover, multiple linear regression analysis showed that the serum endocan level and proteinuria level at baseline were independent predictors for the extent of decline in urine volume.

Conclusions

The results of this study indicate that serum endocan level and proteinuria level may be useful predictive markers for decreased urine volume in PD patients.

Advances in Understanding and Management of Residual Renal Function in Patients with Chronic Kidney Disease

BACKGROUND

Residual renal function (RRF), defined as the ability of native kidneys to eliminate water and uremic toxins, is closely correlated with mortality and morbidity rates among patients receiving either peritoneal dialysis (PD) or hemodialysis (HD) via continuous clearance of middle-sized molecules and protein-bound solutes. Therefore, preserving RRF is considered to be one of the primary goals in managing patients with end-stage renal disease (ESRD).

SUMMARY AND KEY MESSAGES

In this article, we provide a review on the understanding and management of RRF in patients on dialysis. RRF may be estimated and measured by calculating the mean 24-hour urine creatinine level and urea clearance. Currently, several middle-sized molecules are reported but rarely used in practice. Many risk factors such as original renal diseases, dietary intake, and nephrotoxic agents impair RRF. Targeting such factors may halt the decline in RRF and offer better outcomes for patients on PD or HD. Except for in PD patients, RRF is a powerful predictor of survival in HD patients. RRF requires more clinical and research attention in the care of patients with ESRD on dialysis.

The Impact of Fluid Overload and Variation on Residual Renal Function in Peritoneal Dialysis Patient

BACKGROUND

The effect of fluid overload and variation on residual renal function (RRF) in peritoneal dialysis (PD) patients is controversial.

METHODS

Retrospective cohort study was designed. One-hundred and ninety PD patients with measured glomerular filtration rate (mGFR) ≧ 3 ml/min/1.73 m2 were recruit. Fluid status of every participant was assessed by bioelectrical impedance analysis (BIA) every 3 months for 1 year. The cohort was divided into three hydration groups, namely persistent overhydration (PO) group, intermittent overhydration (IO) group and normal hydration (NH) group. Additionally, participants were also divided into high or low fluid variation groups. The decline rate of RRF and the event of anuria were followed up for 1 year. The association of fluid overload with RRF loss was evaluated by Cox proportional hazard models adjusted for confounders.

RESULTS

Thirty-six (18.9%) patients developed anuria. The decline rate of mGFR in both PO and IO groups were significantly faster than that of NH group (PO vs NH: -0.2 vs -0.1 ml/min/1.73 m2/month, p < 0.01; IO vs NH: -0.2 vs -0.1 ml/min/1.73 m2/month, p < 0.01). Kaplan-Meier analysis showed poorer RRF outcome in both PO and IO groups compared with that of NH group (PO vs NH: p < 0.001; IO vs NH: p = 0.006). Patients with high fluid variation had worse RRF survival than those with low fluid variation (p = 0.04). Adjusted Cox regression models indicated the hazard ratio of RRF loss in PO group was 8.90-folds higher (95% confidence interval 3.07-31.89) than that in NH group.

CONCLUSIONS

These findings suggested fluid overload was independently associated with the decline of RRF in PD patients.

Rate of Decline of Residual Kidney Function Before and After the Start of Peritoneal Dialysis

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BACKGROUND

There is a paucity of information on whether peritoneal dialysis (PD) slows the decline of residual kidney function (RKF) compared to the natural slope of RKF decline prior to dialysis start. Our aim was to analyze the RKF decline before and after initiating PD, and to determine the principal factors affecting this decline during the PD period. ♦

METHODS

We determined individual glomerular filtration rates (GFR) for approximately 12 months before and after PD in 77 new PD patients in a large academic medical center (2008 - 2012). The GFR was estimated by the Modification of Diet in Renal Disease (MDRD) equation in the predialysis period and by averaging 24-hour urine creatinine and urea clearances in the PD period. The rate of RKF decline was calculated using unadjusted linear regression analysis. Wilcoxon signed rank test was used to compare RKF decline before and after PD initiation. Multivariate linear regression was used to identify independent risk factors for RKF decline in the PD phase. ♦

RESULTS

A significantly slower mean rate of RKF decline was observed in the PD period compared with the predialysis period (-0.21 ± 0.30 vs -0.59 ± 0.55 mL/min/1.73 m(2)/month, p < 0.01). Higher baseline RKF, higher serum phosphate, and older age were independently associated with faster decline of RKF (all p < 0.01). ♦

CONCLUSIONS

In patients with advanced chronic kidney disease, initiating PD was associated with a slower rate of RKF decline compared to the rate in the predialysis period.

Risk factors for loss of residual renal function in children treated with chronic peritoneal dialysis

In dialyzed patients, preservation of residual renal function is associated with better survival, lower morbidity, and greater quality of life. To analyze the evolution of residual diuresis over time, we prospectively monitored urine output in 401 pediatric patients in the global IPPN registry who commenced peritoneal dialysis (PD) with significant residual renal function. Associations of patient characteristics and time-variant covariates with daily urine output and the risk of developing oligoanuria (under 100 ml/m²/day) were analyzed by mixed linear modeling and Cox regression analysis including time-varying covariates. With an average loss of daily urine volume of 130 ml/m² per year, median time to oligoanuria was 48 months. Residual diuresis significantly subsided more rapidly in children with glomerulopathies, lower diuresis at start of PD, high ultrafiltration volume, and icodextrin use. Administration of diuretics significantly reduced oligoanuria risk, whereas the prescription of renin–angiotensin system antagonists significantly increased the risk oligoanuria. Urine output on PD was significantly associated in a negative manner with glomerulopathies (−584 ml/m²) and marginally with the use of icodextrin (−179 ml/m²) but positively associated with the use of biocompatible PD fluid (+111 ml/m²). Children in both Asia and North America had consistently lower urine output compared with those in Europe perhaps due to regional variances in therapy. Thus, in children undergoing PD, residual renal function depends strongly on the cause of underlying kidney disease and may be modifiable by diuretic therapy, peritoneal ultrafiltration, and choice of PD fluid.

Control of fluid balance guided by body composition monitoring in patients on peritoneal dialysis (COMPASS): study protocol for a randomized controlled trial

Background

The clinical benefits of bioimpedance spectroscopy (BIS)-guided fluid management in patients on hemodialysis have been widely demonstrated. However, no previous reports have evaluated the effect of regular and serial BIS-guided fluid management on the residual renal function (RRF) in patients on peritoneal dialysis (PD). Therefore, we will evaluate the clinical efficacy of BIS-guided fluid management for preserving RRF and protecting cardiovascular events in patients on PD.

Methods/design

This is a multicenter, prospective, randomized controlled trial. A total of 138 participants on PD will be enrolled and randomly assigned to receive either BIS-guided fluid management or fluid management based only on the clinical information for 1 year. The primary outcome is the change in the glomerular filtration rate (GFR) between months 0 and 12 after starting treatment. The secondary outcomes will include GFR at month 12, time to the anuric state (urine volume <100 ml/day), and fatal and nonfatal cardiovascular events during treatment.

Discussion

This is the first clinical trial to investigate the effect of BIS-guided fluid management on RRF and for protecting against cardiovascular events in patients on PD.

Trial registration

Clinical Trials.gov number NCT01887262, June 24, 2013.

Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers for preserving residual kidney function in peritoneal dialysis patients

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEis) and angiotensin receptor blockers (ARBs) are widely used in peritoneal dialysis (PD) patients, yet controversy exists about their impact on residual kidney function.

OBJECTIVES

This review aimed to evaluate the benefits and harms of ACEis and ARBs for preserving residual kidney function in PD patients.

SEARCH METHODS

The Cochrane Renal Group's specialised register, Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE (OvidSP interface), Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI) and other resources were searched by applying a prespecified comprehensive search strategy. Date of last search: 01 May 2014.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing ACEis or ARBs with placebo, other antihypertensive drugs or each other in PD patients were included.

DATA COLLECTION AND ANALYSIS

Screening, selection, data extraction and quality assessments for each retrieved article were carried out by two authors using standardised forms. Authors were contacted when published data were incomplete. Statistical analyses were performed using the random effects model and results expressed as risk ratio (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I² test, subgroup analyses and random effects meta-regression.

MAIN RESULTS

Six open-label studies (257 patients) were identified. One study compared ACEi with other antihypertensive drugs, three compared ARBs with other antihypertensive drugs, and two studies compared an ARB with an ACEi. Long-term use (≥ 12 months) of an ARB showed significantly benefit of preserving residual kidney function in continuous ambulatory PD (CAPD) patients (MD 1.11 mL/min/1.73 m², 95% CI 0.38 to 1.83), although there was no significant benefit when an ARB were used short-term (≤ six months). One study showed that compared with other antihypertensive drugs, long-term use (12 months) of the ACEi ramipril showed a significant reduction in the decline of residual kidney function in patients on CAPD (MD -0.93 mL/min/1.73m², 95% CI -0.75 to -0.11), and delayed the progression to complete anuria (RR 0.64, 95% CI 0.41 to 0.99). There was no significant difference in serum potassium, urinary protein excretion, Kt/V, weekly creatinine clearance and blood pressure for ARBs versus other antihypertensive drugs. Compared with other antihypertensive drugs, ramipril showed no difference in mortality and cardiovascular events. Compared with an ACEi, ARBs did not show any difference in residual kidney function.The selection bias assessment was low in four studies and unclear in two. Five studies were open-label; however the primary outcome (residual kidney function) was obtained objectively from laboratory tests, and were not likely to be influenced by the lack of blinding. Reporting bias was unclear in all six studies.

AUTHORS' CONCLUSIONS

Compared with other antihypertensive drugs, long-term use (≥ 12 months) of ACEis or ARBs showed additional benefits of preserving residual kidney function in CAPD patients. There was no significant difference on residual kidney function preservation between ARBs and ACEis. However, limited by the small number of RCTs enrolling small number of participants, there is currently insufficient evidence to support the use of an ACEi or an ARB as first line antihypertensive therapy in PD patients.

Comparison of the impact of "fast decline" in residual renal function and "initial anuria" on long-term outcomes in CAPD patients

BACKGROUND

Residual renal function (RRF) is pivotal to long-term outcomes, while rapid RRF decline (RRFD) is associated with mortality risk for continuous ambulatory peritoneal dialysis (CAPD) patients. This study was conducted to compare the impact of "initial anuria" and rapid RRFD on the long-term prognosis of CAPD patients.

METHOD

According to the timing of anuria and the slope of RRFD, a total of 255 incident CAPD patients were divided into 3 groups. For the "anuria" group, anuria was detected from CAPD initiation and persisted for > 6 months (n = 27). Based on the median of the RRFD slope, the other 228 non-anuric patients were divided into a "slow decliner" group (n = 114), and a "rapid decliner" group (n = 114). The maximal observation period was 120 months.

RESULTS

Logistic regression tests indicated that the "anuria" group was associated with previous hemodialysis > 3 months (odds ratio [OR]: 8.52, 95% confidence interval [CI]: 3.12 - 23.28), and female (OR: 0.29, 95% CI: 0.09 - 0.90), while the "fast decliner" group with higher Davies co-morbidity scores (DCS) (OR: 1.52; 95% CI: 1.08 - 2.14), body mass index (BMI) (OR: 1.12; 95% CI: 1.04 - 1.21), and male (OR: 1.12; 95% CI: 1.04 - 1.21). After adjusting for DCS, the "fast decliner" group (hazard ratio [HR]: 0.37; 95% CI: 0.17 - 0.80) showed a better outcome than that of the "anuria" group (reference = 1). Both baseline RRF (β = -0.24; p < 0.001) and DCS (β = -3.76; p < 0.001) showed inverse linear correlations to the slope of RRFD. From the Cox proportional analyses, higher baseline RRF (HR: 0.92; 95% CI: 0.88 -.97) and higher slope of RRFD (slower decline in RRF) (HR: 0.90; 95% CI: 0.85 - 0.96) were independent factors for less mortality risk in patients with DCS = 0. However, only a higher slope of RRFD (HR: 0.97; 95% CI: 0.94 - 0.99) was significant for better survival in CAPD patients with DCS > 0.

CONCLUSION

Compared to the baseline RRF, CAPD patients with co-morbidities that rapidly deteriorate RRFD are more crucially associated with long-term mortality risk.

Novel predictors of peritonitis-related outcomes in the BRAZPD cohort

INTRODUCTION

Peritonitis remains the main cause of peritoneal dialysis (PD) technique failure worldwide, despite significant reductions in infection rates observed over the past decades. Several studies have described risk factors for peritonitis, technique failure and mortality. However, there are scarce data regarding predictors of complications during and after a peritonitis episode. The aim of our study was to analyze predictors of peritonitis-related outcome in the Brazilian Peritoneal Dialysis study (BRAZPD) cohort.

METHODS

All adult incident patients recruited in the BRAZPD Study between December 2004 and October 2007, who remained at least 90 days on PD and presented their first peritonitis episode (n = 474 patients) were included in the study. The endpoints analyzed were non-resolution, death due to a peritonitis episode and long-term technique survival after a peritonitis episode.

RESULTS

In the multivariable regression, non-resolution was independently associated with older age (odds ratio (OR) 1.02; p < 0.01), collagenosis as the primary renal disease (OR 4.6; p < 0.05) and Pseudomonas spp as etiological agent (OR 2.9; p < 0.05). Patients who were transferred from APD to CAPD during peritonitis therapy presented a higher risk of non-response (OR 2.5; p < 0.05). The only factor associated with death during a peritonitis episode was older age (OR 1.04; p < 0.05). Exposure to vancomycin and male gender were the independent predictors of long-term technique failure (OR 2.2; p < 0.01).

CONCLUSION

Apart from confirming previous observations of the negative impact of older age and Pseudomonas spp peritonitis on outcomes, we observed that collagenosis may negatively impact response to treatment and exposure to vancomycin may possibly reduce long-term technique survival. It is important to emphasize that the association of vancomycin with technique failure does not prove causality. These findings shed light on new factors predicting outcome when peritonitis is diagnosed.

Controversies in timing of dialysis initiation and the role of race and demographics

Dialysis remains the predominant form of renal replacement therapy in the United States, but the optimal timing for the initiation of dialysis remains poorly defined. Not only clinical factors such as signs/symptoms of uremia, co-existing cardiovascular disease, and presence of diabetes but also key demographic characteristics including age, gender, race/ethnicity, and socioeconomics have all been considered as potential modifying factors in the decision for the timing of dialysis initiation. The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for the Evaluation and Management of chronic kidney disease (CKD) suggests that dialysis be initiated when signs/symptoms attributable to kidney failure such as serositis, acid-base or electrolyte abnormalities, pruritus, poorly controlled volume status or blood pressure, deteriorating nutritional status despite dietary intervention, or cognitive impairment are visible or noted. These signs/symptoms typically occur when the glomerular filtration rate (GFR) is in the range of 5-10 ml/minute/1.73 m(2) , although they may occur at higher levels of GFR. We review recent data on the timing of dialysis initiation, their implications for managing patients with late-stage CKD, and the important role of considering key demographics in making patient-centered decisions for the timing of dialysis initiation.