The Importance of Residual Kidney Function for Patients on Dialysis: A Critical Review

Baseline Residual Kidney Function and Its Ensuing Rate of Decline Interact to Predict Mortality of Peritoneal Dialysis Patients

Background

Baseline residual kidney function (RKF) and its rate of decline during follow-up are purported to be reliable outcome predictors of patients undergoing Peritoneal Dialysis (PD). The independent contribution of each of these factors has not been elucidated.

Method

We report a multicenter, longitudinal study of 493 patients incident on PD and satisfying two conditions: a glomerular filtration rate (GFR) ≥1 mL/minute and a daily diuresis ≥300 mL. The main variables were the GFR (mean of urea and creatinine clearances) at PD inception and the GFR rate of decline during follow-up. The main outcome variable was patient mortality. The secondary outcome variables were: PD technique failure and risk of peritoneal infection. The statistical analysis was based on a multivariate approach, placing an emphasis on the interactions between the two main study variables.

Main Results

Baseline GFR and its rate of decline performed well as independent predictors of both patient mortality and risk of peritoneal infection. These two main study variables maintained a moderate correlation with each other (r² = 0.12, p<0.0005), and interacted clearly, as predictors of patient mortality. A low baseline GFR followed by a fast decline portended the worst survival outcome (adjusted HR 3.84, 95%CI 1.81–8.14, p<0.0005)(Ref. baseline GFR above median plus rate of decline below median). In general, the rate of decline of RKF had a greater effect on mortality than baseline GFR, which had no detectable effect on survival when the decline of RKF was slow (HR 1.17, 95% CI 0.81–2.22, p = 0.22). Conversely, a relatively high GFR at the start of PD still carried a significant risk of mortality, when RKF declined rapidly (HR 1.89, 95% CI 1.05–3.72, p = 0.028).

Conclusion

The risk-benefit balance of an early versus late start of PD cannot be evaluated without taking into consideration the rate of decline of RKF. This circumstance may contribute to explain the controversial results observed at the time of evaluating the potential benefits of an early initiation of PD.

The Trio Trial - A Randomized Controlled Clinical Trial Evaluating the Effect of a Biocompatible Peritoneal Dialysis Solution on Residual Renal Function

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BACKGROUND AND OBJECTIVE

Residual renal function (RRF) correlates with mortality and morbidity rates in patients receiving peritoneal dialysis (PD). We examined the effect of a biocompatible PD solution (Gambrosol Trio; Gambro Lundia AB, Lund, Sweden) with lower concentrations of glucose degradation products on rates of decline in RRF. ♦

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Incident patients at 2 centers in Canada and 1 in Hong Kong were randomized (by minimization) in an open-label parallel group trial to receive Gambrosol Trio or standard PD solution (Dianeal; Baxter Healthcare, Mississauga, Canada) for 2 years. Primary outcome was slope of RRF. Secondary outcomes were urine volumes, fluid and nutrition indices, PD and membrane characteristics, peritonitis rates, adverse events, and PD technique survival. ♦

RESULTS

Residual renal function declined by 0.132 mL/minute/1.73 m(2)/month in 51 patients allocated to biocompatible, and 0.174 mL/minute/1.73 m(2)/month in 50 patients allocated to standard PD solution (difference 0.042 mL/minute/1.73 m(2)/month, p = 0.001). Urine volume, body mass index, normalized protein catabolic rates, and fat mass were higher; total body water, peritoneal ultrafiltration, and D/P creatinine did not differ; and serum phosphate, rates of icodextrin, and automated cycler use were lower with Gambrosol Trio use. There were more peritonitis events with Gambrosol Trio use, while PD technique survival did not differ between groups. ♦

CONCLUSIONS

The use of the biocompatible PD solution Gambrosol Trio was associated with slower rates of decline in RRF, fluid and nutrition benefits, and increased peritonitis rates.

TRIAL NUMBER

ISRCTN26252543.

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.

Urgent peritoneal dialysis or hemodialysis catheter dialysis

Worldwide, there is a steady incident rate of patients with end-stage kidney disease (ESKD) who require renal replacement therapy. Of these patients, approximately one-third have an "unplanned" or "urgent" start to dialysis. This can be a very challenging situation where patients have either not had adequate time for education and decision making regarding dialysis modality and appropriate dialysis access, or a decision was made and plans were altered due to unforeseen circumstances. Despite such unplanned starts, clinicians must still consider the patient's ESKD "life-plan", which includes the best initial dialysis modality and access to suit the patient's individual goals and their medical, social, logistic, and facility circumstances. This paper will discuss the considerations of peritoneal dialysis and a peritoneal dialysis catheter access and hemodialysis and central venous catheter access in patients who require an urgent start to dialysis.

Comparison of Clinical Outcome Between Twice-Weekly and Thrice-Weekly Hemodialysis in Patients With Residual Kidney Function

Residual kidney function (RKF) contributes to improved survival in hemodialysis (HD) patients. However, it is not clear whether RKF allows a comparable survival rate in patients undergoing twice-weekly HD compared with thrice-weekly HD.We enrolled 685 patients from a prospective multicenter observational cohort. RKF and HD adequacy was monitored regularly over 3-year follow-up. Patients with RKF were divided into groups undergoing twice-weekly HD (n = 113) or thrice-weekly HD (n = 137). Patients without RKF undergoing thrice-weekly HD (n = 435) were included as controls. Fluid balance and dialysis-associated characteristics were followed and clinical outcomes evaluated using all-cause mortality and cardiovascular events (CVE).In patients with RKF, baseline and follow-up RKF were significantly higher in patients undergoing twice-weekly HD than in those undergoing thrice-weekly HD. Total Kt/V urea (dialysis plus residual renal) in patients with RKF undergoing twice-weekly HD was greater than or equal to those in patients with or without RKF undergoing thrice-weekly HD. Compared with patients with RKF undergoing thrice-weekly HD, patients with RKF undergoing twice-weekly HD had no fluid excess, but their normalized protein catabolic rate became lower since 24-month follow up. In multivariable analyses, patients with RKF undergoing twice-weekly HD had a noninferior risk of mortality (hazard ratio [HR], 0.83; 95% confidence interval [95% CI], 0.34-2.01, P = 0.68) and of CVE (HR, 0.60; 95% CI, 0.28-1.29, P = 0.19) compared with patients without RKF undergoing thrice-weekly HD. However, this group showed an independent association with a greater risk of mortality compared with patients with RKF undergoing thrice-weekly HD (HR, 4.20; 95% CI, 1.02-17.32, P = 0.04).In conclusion, patients with RKF undergoing twice-weekly HD had an increased risk of mortality compared with those undergoing thrice-weekly HD. Decisions about twice-weekly HD should consider not only RKF, but also other risk factors such as normalized protein catabolic rate.

Impact of dialysis modality on technique survival in end-stage renal disease patients

BACKGROUND/AIMS

This study analyzed the risk factors for technique survival in dialysis patients and compared technique survival rates between hemodialysis (HD) and peritoneal dialysis (PD) in a prospective cohort of Korean patients.

METHODS

A total of 1,042 patients undergoing dialysis from September 2008 to June 2011 were analyzed. The dialysis modality was defined as that used 90 days after commencing dialysis. Technique survival was compared between the two dialysis modalities, and the predictive risk factors were evaluated.

RESULTS

The dialysis modality was an independent risk factor predictive of technique survival. PD had a higher risk for technique failure than HD (hazard ratio [HR], 10.8; 95% confidence interval [CI], 1.9 to 62.0; p = 0.008) during a median follow-up of 11.0 months. In the PD group, a high body mass index (BMI) was an independent risk factor for technique failure (HR, 1.3; 95% CI, 1.0 to 1.8; p = 0.036). Peritonitis was the most common cause of PD technique failure. The difference in technique survival between PD and HD was more prominent in diabetic patients with a good nutritional status and in non-diabetic patients with a poor nutritional status.

CONCLUSIONS

In a prospective cohort of Korean patients with end-stage renal disease, PD was associated with a higher risk of technique failure than HD. Diabetic patients with a good nutritional status and non-diabetic patients with a poor nutritional status, as well as patients with a higher BMI, had an inferior technique survival rate with PD compared to HD.

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.

Association between medical insurance type and survival in patients undergoing peritoneal dialysis

Background

Socioeconomic characteristics may affect the outcomes of patients treated with peritoneal dialysis (PD). There are two major medical insurances in China: the New Cooperative Medical Scheme (NCMS), mainly for rural residents, and the Urban Employees’ Medical Insurance (UEMI). The aim of the present study was to assess the effect of medical insurance type on survival of patient undergoing PD.

Method

This was a prospective study in adult patients who underwent PD at the Wuhan No.1 Hospital between January 2008 and December 2013. Patients had received continuous ambulatory PD for >3 months. Patients were divided according to their medical insurance. Demographic and socioeconomic data, biochemical parameters and primary clinical outcomes including all-cause mortality, switch to hemodialysis and kidney transplantation were analyzed.

Result

There were 415 patients with UEMI and 149 with NCMS. Compared with UEMI, patients with NCMS were younger, and had shorter dialysis duration, smaller proportion of diabetic nephropathy, more severe anemia, and more frequent hyperphosphatemia and hyperuricemia. Total Kt/V, creatinine clearance and residual renal function were not different. There was no difference in technique survival (P > 0.05) between the two groups, but rural patients showed lower overall survival (P < 0.05). Multivariate analysis showed that NCMS was independently associated with lower survival (RR = 1.49; 95% CI = 1.04-2.15).

Conclusions

Medical insurance model is independently associated with PD patient survival.

Compared decline of residual kidney function in patients treated with automated peritoneal dialysis and continuous ambulatory peritoneal dialysis: a multicenter study

BACKGROUND

There is controversy concerning the compared rates of decline of residual kidney function (RKF) in patients treated with continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD).

OBJECTIVES AND METHOD

Following an observational, multicenter design, we studied 493 patients initiating peritoneal dialysis (PD) in four different Spanish units. We explored the effect of the PD modality on the rate of decline of RKF and the probability of anuria during follow-up. We applied logistic regression for intention-to-treat analyses, and linear mixed models to explore time-dependent variables, excluding those affected by indication bias.

MAIN RESULTS

Patients started on APD were younger and less comorbid than those initiated on CAPD. Baseline RKF was similar in both groups (p = 0.50). Eighty-seven patients changed their PD modality during follow-up. The following variables predicted a faster decline of RKF: higher (rate of decline) or lower (anuria) baseline RKF, younger age, proteinuria, nonprimary PD, use of PD solutions rich in glucose degradation products, higher blood pressure, and suffering peritonitis or cardiovascular events during follow-up. Overall, APD was not associated with a fast decline of RKF, but stratified analysis disclosed that patients with lower baseline RKF had an increased risk for this outcome when treated with this technique (HR: 2.26, 95% CI: 1.09-4.82, p = 0.023). Moreover, the probability of anuria during follow-up was overtly higher in APD patients (HR: 3.22, 95% CI: 1.25-6.69, p = 0.002).

CONCLUSIONS

Starting PD patients directly on APD is associated with a faster decline of RKF and a higher risk of developing anuria than doing so on CAPD. This detrimental effect is more marked in patients initiating PD with lower levels of RKF.

Peritoneal Dialysis as a First versus Second Option after Previous Haemodialysis: A Very Long-Term Assessment

For renal replacement therapy, overall survival is more important than the choice of currently available individual therapy. Objectives. To compare patients and technique survival on peritoneal dialysis as first treatment (PDF) versus after previous haemodialysis (HDPD) and other indicators of follow-up. Methods. We prospectively studied 110 incident patients, during the period from August 4, 1993, to June 30, 2012, for patients and technique survival (Kaplan-Meier) (log rank P < 0.05). Results. Groups: (A) PDF: 37 patients, 24 females, age: 52.2 ± 14.9 years old, time at risk: 2123 patient-months (p/m), mean: 57 ± 42 months; (B) HDPD: 73 patients, 42 females, age: 52.45 ± 14.7 years old, time in haemodialysis: 3569.2 (p/m), range: 3-216 months, mean: 49 ± 45 months, time at risk in PD: 3700 (p/m), mean: 51 ± 49 months. Patients' survival: (A) PDF: 100%, 76.6%, 65.6%, and 19.7%; (B) HDPD: 95.4%, 65.6%, 43%, and 43% at 12, 60, 120, and 144 months, respectively, P = 0.34.

TECHNIQUE

(A) PDF: 100%, 90%, 59.8%, and 24%; (B) HDPD: 94%, 75%, 32%, and 32% at 12, 60, 120, and 144 months, respectively, P = 0.40. Conclusions. Comparable patient and technique survival were observed. Peritoneal dialysis enables a greater extension of renal replacement therapy for patients with serious difficulties continuing with haemodialysis.

The Impact of Timing of Dialysis Initiation on Mortality in Patients with Peritoneal Dialysis

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BACKGROUND

The impact of timing of dialysis initiation on mortality is controversial in patients with peritoneal dialysis (PD). In this study, we analyzed the impact of timing of dialysis initiation on mortality in the incident PD population. ♦

METHODS

Incident patients with PD were selected from the Clinical Research Center (CRC) registry for end-stage renal disease (ESRD), a prospective cohort study on dialysis in Korea. Patients were categorized into 3 groups according to the estimated glomerular filtration rate (eGFR) at the initiation of PD using the Modification of Diet in Renal Disease (MDRD) equation. Group A was defined as eGFR < 5 mL/min/1.73m(2), group B as eGFR 5 - 10 mL/min/1.73m(2), and group C as eGFR > 10 mL/min/1.73m(2). Cox regression analysis was used to calculate the adjusted hazard ratio (HR) of mortality with group B as the reference. The primary outcome was all-cause mortality. ♦

RESULTS

A total of 495 incident PD patients were included. The number of patients in group A was 109, group B was 279, and group C was 107. The median follow-up period was 23 months. Multivariate Cox regression analysis showed that group A had a significantly higher risk of all-cause mortality compared with group B (HR 4.13, 95% confidence interval [CI], 1.55 - 11.03, p = 0.005) after adjustment for age, gender, cause of ESRD, serum albumin level, diabetes mellitus, and cardiovascular disease. There was no significant difference in mortality between group C and group B (HR 1.50, 95% CI, 0.59 - 3.80, p = 0.398) after adjustment for clinical variables. ♦

CONCLUSION

An eGFR < 5 mL/min/1.73m(2) at the initiation of PD was a significant risk factor for death, while an eGFR >10 mL/min/1.73m(2) at the initiation of PD was not associated with improved survival compared with an eGFR of 5 - 10 mL/min/1.73m(2) at the initiation of PD.

Preserving residual renal function in dialysis: what we know

Residual renal function confers a survival benefit among dialysis patients thought to be related to greater volume removal and solute clearance. Whether the presence of residual renal function is protective or merely a marker for better health is not clear. The basic mechanisms governing the decline or persistence of residual renal function are poorly understood and few studies have examined the role of medical therapy in its preservation. Dialysis modality, inflammatory processes often associated with comorbid diseases (including diabetes mellitus and obesity), volume dysregulation, and vitamin D deficiency are predictive of residual renal function decline. We review potential mechanisms for preservation of remaining glomerular filtration rate among chronic dialysis patients.

Endothelial dysfunction is associated with major adverse cardiovascular events in peritoneal dialysis patients

Endothelial dysfunction is implicated in increased cardiovascular risk in nondialyzed population. However, the prognostic impact of endothelial dysfunction on cardiovascular outcome has not been investigated in peritoneal dialysis (PD) patients. We prospectively determined endothelial function by brachial artery endothelium-dependent vasodilation (flow-mediated dilation [FMD]) in 143 nondiabetic PD patients and 32 controls. Primary outcome was a major adverse cardiac and cerebrovascular event (MACCE). Brachial FMD was significantly lower in PD patients than in controls (2.9% [1.3-4.7] vs 6.2% [5.4-8.3], P < 0.001). During a mean follow-up of 42 months, primary outcome was observed in 25 patients (17.5%). When patients were dichotomized by the median value of FMD (2.9%), incidence rates of MACCEs were significantly higher in the group with lower FMD compared with higher FMD (7.2 vs 3.0/100 person-years, P = 0.03). In multivariate Cox analysis, low FMD (≤2.9%) was a significant independent predictor of MACCEs (hazard ratio = 2.73, 95% confidence interval = 1.03-7.22, P = 0.04). Furthermore, multivariate fractional polynomial analysis showed that the risk of MACCE decreased steadily with higher FMD values. Impaired brachial FMD was a significant independent predictor of MACCEs in PD patients. Estimating endothelial dysfunction by brachial FMD could be useful for stratifying cardiovascular risk in these patients.

Choosing wisely and beyond: shared decision making and chronic kidney disease

In 2012, the Kaiser Permanente Area Medical Directors of Quality decided to sponsor analytic activities to improve shared decision making for patients with chronic kidney disease. The objective was to move shared decision making for renal replacement therapy or maximal conservative management upstream rather than waiting until the patient presented to the emergency room requiring acute dialysis. Nephrologists have multiple opportunities to discuss treatment options with patients throughout the course of their disease. However, despite these opportunities most patients beginning dialysis have not experienced shared decision making with their physicians. The shared-decision-making process may help patients understand the importance of being prepared to start dialysis and the benefits of maximal conservative management.By having these discussions upstream we may be able to improve survival (save lives), slow down renal disease progression (save kidneys), preserve central veins for future vascular access (save veins), and be better stewards of finite resources needed to care for patients with end-stage kidney disease (save resources).

Association of initial twice-weekly hemodialysis treatment with preservation of residual kidney function in ESRD patients

BACKGROUND

Residual kidney function (RKF) has consistently been a predictor of greater survival in maintenance hemodialysis (MHD) patients. The relationship between hemodialysis (HD) treatment frequency and RKF preservation has not been well examined. We hypothesized that initial twice-weekly HD helps in maintaining a longer RKF.

METHODS

In a dialysis center in Shanghai, 168 ESRD patients were screened and finally 85 patients were identified for this main cohort study. We first examined these 85 MHD patients; 30 of them were initiated with twice-weekly HD for 6 months or longer and 55 patients were started and maintained on thrice-weekly HD treatment. Then a subcohort study in 48 incident MHD patients was implemented to assess the independent risk factors responsible for RKF decline during the first year of HD therapy. Multivariate logistic regression analysis was then employed to examine the odds ratio of RKF loss.

RESULTS

The main cohort study showed that the clinical outcomes were almost the same between the two groups in 85 patients, but the percent of patients with RKF loss was significantly lower in the twice-weekly group compared with the thrice-weekly group, especially during the first year of HD initiation. In the 48 incident MHD patients, we found no significant differences between the two groups except for variations in the HD frequency, weekly Kt/V. The multivariate analysis showed that factors such as the male gender, HD frequency, URR and intradialytic hypotension episode were associated with RKF loss, and the odds ratio of RKF loss for each additional HD treatment per week was 7.2.

CONCLUSION

Twice-weekly HD during the first year of dialysis therapy appears to be associated with better RKF preservation.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Sonographic measurement of renal size in patients undergoing chronic hemodialysis: Correlation with residual renal function

Previous studies have reported that renal size may change when the function is compromised. However, it is not known whether sonographically measured renal size reflects the residual renal function (RRF) in patients undergoing chronic hemodialysis. A total of 140 patients undergoing chronic hemodialysis (≥3 months) were investigated in the present study. The patients were divided into two groups according to the daily urine volume: Individuals with RRF (RRF+ group; ≥200 ml; n=65) and without RRF (RRF− group; <200 ml; n=75). Renal sizes were measured using sonography and renal volumes were calculated with the ellipsoid formula. Univariable and multivariable stepwise forward logistic regression analyses were performed to examine the correlation between the presence of RRF and various variables. The results indicated that there were statistically significant differences (P<0.001) between the RRF+ and RRF− groups with regard to renal length, width, thickness and volume of the left (length, 7.9±1.2 vs. 6.8±1.2 cm; volume, 60.0±26.7 vs. 40.2±18.1 ml, respectively) and right (length, 7.6±1.2 vs. 6.7±1.2 cm; volume, 50.2±26.5 vs. 33.9±15.3 ml, respectively) sides of the kidney. Multivariable stepwise forward logistic regression analyses showed that the mean renal length or volume and hemodialysis duration were independent predictors of the presence of RRF. Therefore, renal size assessment by ultrasonography may be useful for RRF evaluation in patients undergoing chronic hemodialysis.

Long-term effects of spironolactone in peritoneal dialysis patients

ESRD treated with dialysis is associated with increased left ventricular hypertrophy, which, in turn, is related to high mortality. Mineralocorticoid receptor antagonists improve survival in patients with chronic heart failure; however, the effects in patients undergoing dialysis remain uncertain. We conducted a multicenter, open-label, prospective, randomized trial with 158 patients receiving angiotensin-converting enzyme inhibitor or angiotensin type 1 receptor antagonist and undergoing peritoneal dialysis with and without (control group) spironolactone for 2 years. As a primary endpoint, rate of change in left ventricular mass index assessed by echocardiography improved significantly at 6 (P=0.03), 18 (P=0.004), and 24 (P=0.01) months in patients taking spironolactone compared with the control group. Rate of change in left ventricular ejection fraction improved significantly at 24 weeks with spironolactone compared with nontreatment (P=0.02). The benefits of spironolactone were clear in patients with reduced residual renal function. As secondary endpoints, renal Kt/V and dialysate-to-plasma creatinine ratio did not differ significantly between groups during the observation period. No serious adverse effects, such as hyperkalemia, occurred. In this trial, spironolactone prevented cardiac hypertrophy and decreases in left ventricular ejection fraction in patients undergoing peritoneal dialysis, without significant adverse effects. Further studies, including those to determine relative effectiveness in women and men and to evaluate additional secondary endpoints, should confirm these data in a larger cohort.

Effect of peritoneal dialysis modality on the 1-year rate of decline of residual renal function

PURPOSE

The effect of different peritoneal dialysis (PD) modalities on the decline in residual renal function (RRF) is unclear due to inconsistencies among studies. In particular, the effect of automated peritoneal dialysis (APD) modalities [continuous cyclic peritoneal dialysis (CCPD) and nightly intermittent peritoneal dialysis (NIPD)] on RRF has not been examined in a large cohort.

MATERIALS AND METHODS

We conducted a single-center retrospective study to investigate the association between PD modalities and decline in RRF in 142 incident PD patients [34 on CCPD, 36 on NIPD, and 72 on continuous ambulatory peritoneal dialysis (CAPD)]. RRF was measured within 2 months from PD start and at 1 year after PD initiation.

RESULTS

The RRF at 1 year after PD initiation was 1.98±2.20 mL/min/1.73 m² in CCPD patients and 3.63±3.67 mL/min/1.73 m² in NIPD patients, which were moderately lower than 4.23±3.51 mL/min/1.73 m² in CAPD patients (p=0.064). Moreover, there was no significant difference in the 1-year rate of decline of RRF between CCPD and NIPD patients, although APD patients had a faster 1-year RRF decline rate than CAPD patients (CCPD and NIPD vs. CAPD: -45.68 and -36.69 vs. 1.17%/year, p=0.045). APD was associated with a more rapid decline in RRF in patients with end-stage renal disease undergoing PD, although multivariate analysis attenuated the significance of this finding (β=-31.50; 95% CI, -63.61 to 0.62; p=0.052).

CONCLUSION

Our results suggest that CAPD might be more helpful than APD for preserving RRF during the first year of dialysis therapy, although there was no significant difference in the 1-year rate of decline of RRF between the two APD modalities.

Is dialysis modality a factor in the survival of patients initiating dialysis after kidney transplant failure?

BACKGROUND

Kidney transplant failure (TF) is among the leading causes of dialysis initiation. Whether survival is similar for patients treated with peritoneal dialysis (PD) and with hemodialysis (HD) after TF is unclear and may inform decisions concerning dialysis modality selection.

METHODS

Between 1995 and 2007, 16 113 adult dialysis patients identified from the US Renal Data System initiated dialysis after TF. A multivariable Cox proportional hazards model was used to evaluate the impact of initial dialysis modality (1 865 PD, 14 248 HD) on early (1-year) and overall mortality in an intention-to-treat approach.

RESULTS

Compared with HD patients, PD patients were younger (46.1 years vs 49.4 years, p < 0.0001) with fewer comorbidities such as diabetes mellitus (23.1% vs 25.7%, p < 0.0001). After adjustment, survival among PD patients was greater within the first year after dialysis initiation [adjusted hazard ratio (AHR): 0.85; 95% confidence interval (CI): 0.74 to 0.97], but lower after 2 years (AHR: 1.15; 95% CI: 1.02 to 1.29). During the entire period of observation, survival in both groups was similar (AHR for PD compared with HD: 1.09; 95% CI: 1.0 to 1.20). In a sensitivity analysis restricted to a cohort of 1865 propensity-matched pairs of HD and PD patients, results were similar (AHR: 1.03; 95% CI: 0.93 to 1.14). Subgroups of patients with a body mass index exceeding 30 kg/m(2) [AHR: 1.26; 95% CI: 1.05 to 1.52) and with a baseline estimated glomerular filtration rate (eGFR) less than 5 mL/min/1.73 m(2) (AHR: 1.45; 95% CI: 1.05 to 1.98) experienced inferior overall survival when treated with PD.

CONCLUSIONS

Compared with HD, PD is associated with an early survival advantage, inferior late survival, and similar overall survival in patients initiating dialysis after TF. Those data suggest that increased initial use of PD among patients returning to dialysis after TF may be associated with improved outcomes, except among patients with a higher BMI and those who initiate dialysis at lower levels of eGFR. The reasons behind the inferior late survival seen in PD patients are unclear and require further study.

PD First: peritoneal dialysis as the default transition to dialysis therapy

Peritoneal dialysis (PD) and in-center hemodialysis (HD) are accepted as clinically equivalent dialysis modalities, yet in-center HD is the predominant renal replacement therapy (RRT) modality offered to new end-stage renal disease (ESRD) patients in the United States and most other industrialized nations. This predominance has little to do with clinical outcomes, patient choice, cost, or quality of life. It has been driven by ease of HD initiation, physician experience and training, inadequate pre-ESRD patient education, ample in-center HD capacity, and lack of adequate infrastructure for PD-related care. As compared with in-center HD, PD is a widely applicable, yet underutilized modality of RRT that provides comparable clinical outcomes, superior quality of life measures, significant cost savings, and many other unmeasured advantages. A "PD First" approach not only has advantages for patients but also physicians, healthcare systems, and society. In this review, we will summarize evidence demonstrating that PD should be the default modality when new ESRD patients are transitioning to dialysis therapy when preemptive transplantation is not an option and highlight the essential infrastructural requirements to allow for a "PD First" model.

Dialysis initiation: what's the rush?

The recent trend to early initiation of dialysis (at eGFR >10 ml/min/1.73 m(2) ) appears to have been based on conventional wisdoms that are not supported by evidence. Observational studies using administrative databases report worse comorbidity-adjusted dialysis survival with early dialysis initiation. Although some have concluded that the IDEAL randomized controlled trial of dialysis start provided evidence that patients become symptomatic with late dialysis start, there is no definitive support for this view. The potential harms of early start of dialysis, including the loss of residual renal function (RRF), have been well documented. The rate of RRF loss (renal function trajectory) is an important consideration for the timing of the dialysis initiation decision. Patients with low glomerular filtration rate (GFR) may have sufficient RRF to be maintained off dialysis for years. Delay of dialysis start until a working arterio-venous access is in place seems prudent in light of the lack of harm and possible benefit of late dialysis initiation. Prescribing frequent hemodialysis is not recommended when dialysis is initiated early. The benefits of early initiation of chronic dialysis after episodes of congestive heart failure or acute kidney injury require further study. There are no data to show that early start benefits diabetics or other patient groups. Preemptive start of dialysis in noncompliant patients may be necessary to avoid complications. The decision to initiate dialysis requires informed patient consent and a joint decision by the patient and dialysis provider. Possible talking points for obtaining informed consent are provided.

Predicting residual renal function in peritoneal dialysis patients using an estimated glomerular filtration rate based on serum creatinine levels

BACKGROUND

The aim of this study was to evaluate regression equations correcting estimated glomerular filtration rate (eGFR) and the clinical significance of the corrected eGFRs calculated using these equations.

PATIENTS AND METHODS

The authors determined how well corrected eGFR values calculated using regression equations predict residual renal function (RRF).

RESULTS

RRF values were correlated with all eGFR values of nonanuric patients of both genders. Peritoneal creatinine clearance values were not correlated with eGFRs in anuric patients of either gender. In males, eGFR biases ranged from -5.66 to -3.25, and in females, from -5.96 to -3.21. However, these biases decreased when eGFR values were transformed to corrected eGFR values. The area under the curve of the corrected eGFR values was acceptable for a diagnosis of RRF loss.

CONCLUSION

Corrected eGFR values obtained using these methods may provide an alternative means of predicting RRF without 24-hour urine collection.

Metabolic syndrome and abdominal fat are associated with inflammation, but not with clinical outcomes, in peritoneal dialysis patients

Background

In the general population, metabolic syndrome (MetS) is correlated with visceral fat and a risk factor for cardiovascular disease (CVD); however, little is known about the significance of abdominal fat and its association with inflammation and medication use in peritoneal dialysis (PD) patients. We investigated the relationship of visceral fat area (VFA) with C-reactive protein (CRP) levels and medication use in PD patients and followed their clinical outcomes.

Methods

In a prospective study from February 2009 to February 2012, we assessed diabetes mellitus (DM) status, clinical and PD-associated characteristics, medication use, CRP levels, components of MetS, and VFA in 183 PD patients. These patients were categorized into 3 groups based on MetS and DM status: non-MetS (group 1, n = 73), MetS (group 2, n = 65), and DM (group 3, n = 45). VFA was evaluated by computed tomography (CT) and corrected for body mass index (BMI).

Results

Patients in group 1 had smaller VFAs than patients in groups 2 and 3 (3.2 ± 1.8, 4.6 ± 1.9, and 4.9 ± 2.0 cm²/[kg/m²], respectively, P < 0.05) and lower CRP levels (0.97 ± 2.31, 1.27 ± 2.57, and 1.11 ± 1.35 mg/dL, respectively, P < 0.05). VFA increased with the number of criteria met for MetS. After adjusting for age, body weight, and sex, CRP and albumin levels functioned as independent positive predictors of VFA; on other hand, the use of renin-angiotensin system blockers was inversely correlated with VFA in PD patients without DM. In the survival analysis, DM patients (group 3) had the poorest survival among the 3 groups, but no significant differences were found between groups 1 and 2.

Conclusion

This study showed that VFA and MetS are associated with CRP levels but cannot predict survival in PD patients without DM. The complex relationship of nutritional parameters to VFA and MetS may explain these results. The type of antihypertensive medication used was also associated with the VFA. The mechanisms behind these findings warrant further investigation.

Is residual renal function and better phosphate control in peritoneal dialysis an answer for the lower prevalence of valve calcification compared to hemodialysis patients?

INTRODUCTION

Cardiac valve calcification (CVC) has long been regarded as a consequence of abnormal calcium-phosphate metabolism in uremic patient associated with increased cardiovascular mortality in this population. We evaluated the association between residual renal function (RRF), phosphate level and valve calcification in peritoneal dialysis (PD) and hemodialysis (HD) patients.

METHODS

We studied 30 stable PD patients (60 % males; mean age 57 ± 12.36 years) and 34 HD patients (58.8 % males; mean age 50.8 ± 10.4 years) on renal replacement therapy (RRT) from 6 up to 36 months. The presence of CVC was assessed by standard bi-dimensional echocardiography. RRF was calculated by standard technique.

RESULTS

Valve calcification was more frequently found in HD compared to PD patients (70.6 vs 29.4 %, p = 0.007). Significantly lower phosphate [1.38 ± 0.41 versus 1.99 ± 0.35 mmol/L (p < 0.0001)], a higher RRF [4.09 ± 2.09 ml/min vs 0.62 ± 0.89 ml/min (p < 0.0001)], and older age [57 ± 12.36 years vs 50.8 ± 10.4 years (p = 0.033)] were observed in PD as compared to HD patients. The logistic regression analysis for the presence of valve calcification when adjusted for age and diabetes, with type of therapy, serum phosphate, RRF, CRP, and serum albumin as variables in the model, revealed significant association between the presence of valve calcification and age and RRF. The correlation between phosphate levels and RRF was even stronger in PD patients than in HD patients (r = -0.704; p = 0.0001) vs (r = -0.502; p = 0.02).

CONCLUSIONS

Our study shows that the residual renal function in PD patients contributes significantly to the maintenance of phosphate balance and may explain the lower prevalence of valve calcification in PD patients compared with HD patients in the period up to first 3 years under renal replacement therapy.

Accumulation of circulating advanced oxidation protein products is an independent risk factor for ischaemic heart disease in maintenance haemodialysis patients

AIM

Whether the burden of advanced oxidation protein products (AOPP) accumulation, a marker of oxidative stress, is affected by dialysis modality remains unclear. We compared the serum levels of AOPP in patients on haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) and tested the hypothesis that an accumulation of AOPP was an independent risk factor for cardiovascular disease.

METHODS

This was a cross-section study. A total of 2095 patients (1539 HD, 556 CAPD) were recruited from the nine largest dialysis centres in China. Persons in medical centres for disease screening were selected as controls. Patients maintained on HD were dialyzed twice or thrice weekly. CAPD patients used lactate-buffered, glucose-containing solutions. The patients' data were abstracted from the medical record. The serum levels of AOPP were determined by spectrophotometric detection.

RESULTS

The levels of AOPP were significantly elevated in both HD and CAPD patients compared to healthy controls. Accumulation of AOPP was more significant in HD compared to CAPD population. Meanwhile, AOPP accumulation was associated with the presence of ischaemic heart disease (IHD) only in HD, but not CAPD patients. A higher proportion of IHD was found in the HD population among those with higher levels of AOPP in each category of age and irrespective of the presence or absence of high triglyceride. Multivariate regression analysis indicated that accumulation of AOPP was an independent risk factor for IHD in HD population.

CONCLUSION

Accumulation of AOPP was more significant in HD compared to CAPD patients. The level of AOPP was independently associated with IHD only in HD patients.

Bimodal solutions or twice-daily icodextrin to enhance ultrafiltration in peritoneal dialysis patients

The efficacy and safety of icodextrin has been well established. In this paper, we will discuss the pharmacokinetics and biocompatibility of icodextrin and its clinical effect on fluid management in peritoneal dialysis patients. Novel strategies for its prescription for peritoneal dialysis patients with inadequate ultrafiltration are reviewed.

Reliability of endogenous markers for estimation of residual renal function in haemodialysis patients

BACKGROUND

Residual renal function in haemodialysis patients is of increasing interest. However, reproducibility and agreement between methods to measure and estimate glomerular filtration rate (GFR) require further elucidation. The aim of this study was to evaluate the accuracy and reproducibility of GFR estimates based on endogenous markers in haemodialysis patients.

METHODS

Twelve patients were examined twice. GFR was estimated by (i) urine clearances of creatinine, urea and the average of creatinine and urea clearance [U-Cl(crea-urea)]; (ii) an equation based on serum concentration of cystatin C [eGFR(CysC)]. These were compared to (51) Cr-EDTA clearance in plasma [P-Cl(EDTA)] and urine [U-Cl(EDTA)].

RESULTS

U-Cl(crea-urea) produced results similar to U-Cl(EDTA). eGFR(CysC) had a low week-to-week variability. Visually, eGFR(CysC) differed from y = x when compared to the other methods indicating bias, probably due to extrarenal elimination of cystatin C. Coefficients of variation were significantly different, P<0·001: P-Cl(EDTA), 10%; U-Cl(EDTA), 13%; and U-Cl(crea-urea), 13%. P-Cl(EDTA) was 2·1 ml min(-1) 1·73 m(-2) higher than U-Cl(EDTA) (mean).

CONCLUSIONS

Glomerular filtration rate in haemodialysis patients can be estimated from U-Cl(crea-urea) when complete urine collection is performed. The available eGFR(CysC) in haemodialysis patients seemed to be biased, and further development and validation is desirable. P-Cl(EDTA) was the most reproducible method and might be useful in special situations.

Risk factors associated with brachial-ankle pulse wave velocity among peritoneal dialysis patients in Macao

Background

Cardiovascular disease is the leading cause of mortality among peritoneal dialysis (PD) patients in Macao. Increased arterial stiffness determined by pulse wave velocity (PWV) has been established as an independent predictor of cardiovascular mortality in end-stage renal disease patients. The present study aims to investigate the relationship between arterial stiffness and its associated risk factors in chronic PD patients.

Methods

A total of 96 chronic PD patients (48 males/48 females) were included in the cross-sectional study. Arterial stiffness was assessed by brachial-ankle PWV (baPWV). Patients were divided into two subgroups according to mean baPWV value. On enrollment, clinical characteristics and biochemical parameters were collected.

Results

Compared with low baPWV group patients, high baPWV group patients were significant older (p<0.001) and more likely to have a high proportion of female gender (p=0.004) as well as previous CVD history (p=0.008). Serum albumin, pre-albumin levels and residual renal creatinine clearance (CCr) were significantly lower but the serum ferritin level was significantly higher in high baPWV group patients than in low baPWV group patients (all p<0.01). BaPWV was positively associated with age (r=0.534, p<0.001), Charlson comorbidity index (r=0.350, p<0.001) and serum ferritin level (r=0.340, p=0.001). Meanwhile, baPWV negatively correlated with serum albumin (r=−0.479, p<0.001), pre-albumin levels (r=−0.320, p=0.003) and residual renal CCr (r=−0.177, p=0.048). Age-adjusted partial correlation test found a significant correlation between baPWV and CRP (r=0.462, p<0.001). Multivariate regression analysis showed that baPWV was independently associated with age (p<0.001), serum albumin level (p=0.015), CRP (p=0.019) and residual renal CCr (p=0.045).

Conclusion

Arterial stiffness, assessed by baPWV, had an independent correlation with age, serum albumin level, CRP level and residual renal CCr among PD patients in Macao.

Prevalence and risk factors associated with peripheral artery disease in elderly patients undergoing peritoneal dialysis

BACKGROUND

Rapid growth of the elderly peritoneal dialysis (PD) population is posing a special challenge for renal teams. Peripheral artery disease (PAD) has been reported to be an independent predictor of cardiovascular and all-cause mortality in hemodialysis patients. However, the prevalence and associated risk factors for PAD in elderly PD patients have not yet been fully investigated.

METHODS

A total of 69 elderly PD patients were included in the present study. PAD was defined as either an ankle-brachial index < 0.9 or a history of intermittent claudication, lower-limb amputation, foot ulcers, or gangrene. On enrollment, clinical and biochemical characteristics were collected.

RESULTS

The overall prevalence of PAD was 31.9%. Compared with non-PAD patients, PAD patients were significantly older and more likely to be female and have longer PD duration and lower diastolic blood pressure (P < 0.001, = 0.002, 0.018, and 0.007, respectively). Serum albumin level (P < 0.001) and residual renal Kt/V value (P < 0.001) were significantly lower, but the serum C-reactive protein level (P = 0.005) was significantly higher, in PAD patients compared with non-PAD patients. Logistic regression analysis showed that serum albumin level (odds ratio = 1.485, P = 0.040) and residual renal Kt/V value (odds ratio = 1.725, P = 0.016) were independently associated with PAD.

CONCLUSION

A high prevalence of PAD appeared among elderly PD patients in Macao. Serum albumin level and residual renal Kt/V value were independently related to PAD.

Endogenous markers for estimation of renal function in peritoneal dialysis patients

OBJECTIVE

This method comparison study, conducted at the peritoneal dialysis (PD) outpatient clinic of the Department of Renal Medicine, Aarhus University Hospital, Denmark, set out to evaluate the accuracy and reproducibility of methods for estimating glomerular filtration rate (GFR) based on endogenous markers in PD patients.

PATIENTS

The 12 consecutive patients included in the study were examined twice while in a stable condition. All patients finished the study. Inclusion criteria were age 18 years or older, ability to collect 24-hour urine, and urine production greater than 300 mL in 24 hours.

MAIN OUTCOME MEASURES

The methods for estimating GFR using endogenous markers included the average of urinary clearances of creatinine and urea [U-Cl(crea-urea)] and two equations using the serum concentration of cystatin C [eGFR(CysC)]. The resulting GFR estimates were compared with those obtained using urinary and corrected plasma clearances of (51)Cr-EDTA [U-Cl(EDTA) and cP-Cl(EDTA)], the corrected plasma clearance being plasma clearance minus dialysate clearance.

RESULTS

Compared with the U-Cl(EDTA), the U-Cl(crea-urea) GFR estimate was 12% higher [95% confidence limits (CL): 3%, 21%]. Although significantly different (p = 0.01), the latter two methods showed the best agreement. The estimates obtained using the eGFR(CysC) methods were skewed from y = x compared with the estimates obtained using other methods, indicating strong bias, probably because of extrarenal elimination. The cP-Cl(EDTA) estimate was 34% (95% CL: 26%, 42%), higher than the U-Cl(EDTA) estimate (p < 0.001). The reproducibility (coefficients of variation) differed significantly between methods: cP-Cl(EDTA), 7%; U-Cl(EDTA), 14%; U-Cl(crea-urea), 18%; and both eGFR(CysC) methods, 3%.

CONCLUSIONS

In PD patients, GFR may be estimated as U-Cl(crea-urea) when complete urine collection is performed, taking into account an overestimation of approximately 12%. The available equations for eGFR(CysC) seem to be inaccurate; further development and validation is desirable. Omitting the eGFR(CysC) methods, cP-Cl(EDTA) was the most reproducible method and might be useful in certain situations.

A combination of biocompatible peritoneal dialysis solutions and residual renal function, peritoneal transport, and inflammation markers: a randomized clinical trial

BACKGROUND

The benefits of biocompatible peritoneal dialysis (PD) fluids, particularly for residual renal function (RRF), are controversial. Moreover, the clinical effects of a PD regimen consisting of different biocompatible PD fluids have not been fully established.

STUDY DESIGN

Prospective, randomized, controlled, open-label study.

SETTING & PARTICIPANTS

Patients with end-stage kidney disease newly started on continuous ambulatory PD therapy (N = 150).

INTERVENTION

A 12-month intervention with 3 biocompatible PD fluids (a neutral-pH, low glucose degradation product, 1.5% glucose solution; a solution with 1.1% amino acid; and a fluid with 7.5% icodextrin) or conventional PD fluid.

OUTCOMES

The primary outcome was change in RRF and daily urine volume. Secondary outcomes were peritoneal transport and inflammation markers.

MEASUREMENTS

RRF, daily urine volume, serum and dialysate cytokine levels.

RESULTS

RRF(3.24 ± 1.98 vs 2.88 ± 2.43 mL/min/1.73 m(2); P = 0.9) and rate of decline in RRF (-0.76 ± 1.77 vs -0.91 ± 1.92 mL/min/1.73 m(2) per year; P = 0.6) did not differ between the biocompatible- and conventional-PD-fluid groups. However, patients using the biocompatible PD fluids had better preservation of daily urine volume (959 ± 515 vs 798 ± 615 mL/d in the conventional group, P = 0.02 by comparison of difference in overall change by repeated-measures analysis of variance). Their dialysate-plasma creatinine ratio at 4 hours was higher at 12 months (0.78 ± 0.13 vs 0.68 ± 0.12; P = 0.01 for comparison of the difference in overall change by repeated-measures analysis of variance). They also had significantly higher serum levels of adiponectin and overnight spent dialysate levels of cancer antigen 125, adiponectin, and interleukin 6 (IL-6). No differences between the 2 groups were observed for serum C-reactive protein and IL-6 levels.

LIMITATIONS

Unblinded, relatively short follow-up; no formal sample-size calculations.

CONCLUSIONS

Use of a combination of 3 biocompatible PD fluids for 12 months compared with conventional PD fluid did not affect RRF, but was associated with better preservation of daily urine volume. The biocompatible PD fluids also lead to changes in small-solute transport and an increase in dialysate cancer antigen 125, IL-6, adiponectin, and systemic adiponectin levels, but have no effect on systemic inflammatory response. The clinical significance of these changes, while of great interest, remains to be determined by further studies.

Determinants of left ventricular mass in patients on hemodialysis: Frequent Hemodialysis Network (FHN) Trials

BACKGROUND

An increase in left ventricular mass (LVM) is associated with mortality and cardiovascular morbidity in patients with end-stage renal disease.

METHODS AND RESULTS

The Frequent Hemodialysis Network (FHN) Daily Trial randomized 245 patients to 12 months of 6 times per week daily in-center hemodialysis or conventional hemodialysis; the FHN Nocturnal Trial randomized 87 patients to 12 months of 6 times per week nocturnal hemodialysis or conventional hemodialysis. The main cardiac secondary outcome was change in LVM. In each trial, we examined whether several predefined baseline demographic or clinical factors as well as change in volume removal, blood pressure, or solute clearance influenced the effect of frequent hemodialysis on LVM. In the Daily Trial, frequent hemodialysis resulted in a significant reduction in LVM (13.1 g; 95% CI, 5.0-21.3 g; P=0.002), LVM index (6.9 g/m(2); 95% CI, 2.4-11.3 g/m(2); P=0.003), and percent change in geometric mean of LVM (7.0%; 95% CI, 1.0%-12.6; P=0.02). Similar trends were noted in the Nocturnal Trial but did not reach statistical significance. In the Daily Trial, a more pronounced effect of frequent hemodialysis on LVM was evident among patients with left ventricular hypertrophy at baseline. Changes in LVM were associated with changes in blood pressure (conventional hemodialysis: R=0.28, P=0.01, daily hemodialysis: R=0.54, P<0.001) and were not significantly associated with changes in other parameters.

CONCLUSIONS

Frequent in-center hemodialysis reduces LVM. The benefit of frequent hemodialysis on LVM may be mediated by salutary effects on blood pressure. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00264758.

Timing of dialysis initiation in transplant-naive and failed transplant patients

Over the past two decades, most guidelines have advocated early initiation of dialysis on the basis of studies showing improved survival in patients starting dialysis early. These recommendations led to an increase in the proportion of patients initiating dialysis with an estimated glomerular filtration rate (eGFR) >10 ml/min/1.73 m(2), from 20% in 1996 to 52% in 2008. During this period, the percentage of patients starting dialysis with an eGFR ≥15 ml/min/1.73 m(2) increased from 4% to 17%. However, recent studies have failed to substantiate a benefit of early dialysis initiation and some data have suggested worse outcomes for patients starting dialysis with a higher eGFR. Several reasons for this seemingly paradoxical observation have been suggested, including the fact that patients requiring early dialysis are likely to have more severe symptoms and comorbidities, leading to confounding by indication, as well as biological mechanisms that causally relate early dialysis therapy to adverse outcomes. Patients with a failing renal allograft who reinitiate dialysis encounter similar problems. However, unique factors associated with a failed allograft means that the optimal timing of dialysis initiation in failed transplant patients might differ from that in transplant-naive patients with chronic kidney disease. In this Review, we discuss studies of dialysis initiation and compare risks and benefits of early versus late initiation and reinitiation of dialysis therapy.

Emerging importance of residual renal function in end-stage renal failure

Residual renal function (RRF) is well recognized as an important marker of outcomes in peritoneal dialysis (PD), and contributes vitally to solute clearance. Recently, its importance in hemodialysis (HD) has emerged with evidence that it is strongly associated with improved outcomes. The presence of RRF is associated with improved nutrition, reduced erythropoetin requirements, better potassium clearance, and improved quality of life. Retrospective and observational evidence is now available, which suggests that the presence of RRF is independently associated with survival and that this benefit goes beyond what is expected simply from augmentation of small solute clearance. Preservation of RRF is now considered by many to be an important aspect of dialysis strategy. Evidence in favor of one modality over another for preservation of RRF is conflicting, as are the potential benefits of biocompatible fluids in PD. In HD, the evidence in favor of biocompatible membranes is stronger. Emerging evidence is broadly in favor of angiotensin converting enzyme inhibitors for preservation of RRF. Diuretics appear to have a neutral effect. The complexities and practical difficulties in measurement of RRF have resulted in this important parameter being largely ignored in HD. Novel markers of renal function may provide alternative, simple methods of estimating RRF, which may remove the need for urine collections and simplify its measurement.

Risk factors for mortality in stable peritoneal dialysis patients

BACKGROUND

The mortality rates of end-stage renal disease patients have significantly declined over the past decade. However, there are few reports on the risk factors for mortality in stable peritoneal dialysis (PD) patients who survive for a considerable time.

PATIENTS AND METHODS

We reviewed the medical records and identified all adult patients who received PD between April 2001 and March 2009 in our institution. The total cohort was 550 patients. Among these patients, 383 patients were enrolled as stable PD patients.

RESULTS

The cumulative survival of the stable PD patients was 91.6% at 3 years and 78.7% at 5 years. On univariate analysis, old age (≥65 years of age), hypoalbuminemia (<35 g/L), log C-reactive protein (CRP) (≥0.84), phosphorus (<1.13 mmol/L), statin, icodextrin, and the Davies index were associated with mortality for all PD patients. Old age, hypoalbuminemia, log CRP, phosphorus, the residual renal function (RRF) (≤4 mL/min/1.73 m2) at 24 months, renin-angiotensin system blockade, icodextrin, and the Davies index were associated with mortality for the stable PD patients. Multivariate analysis showed that, among the variables, age, log CRP, phosphorus, initial RRF, and the Davies index were associated with mortality for all PD patients. In stable PD patients, age, log CRP, phosphorus, RRF at 24 months, and the Davies index were associated with mortality.

CONCLUSION

Initial high RRF combined with the RRF preservation, maintenance of proper phosphorus, control of inflammation, and proper management of comorbidities may help to improve the survival of PD patients including stable PD patients.

Reliability of ⁵¹Cr-EDTA plasma and urinary clearance as a measure of residual renal function in dialysis patients

PURPOSE

In dialysis patients, longer survival is associated with a higher residual renal function. Randomized controlled trials are conducted to clarify how residual renal function can be preserved. However, existing methods for measuring residual renal function are uncertain and there is a need for establishing a standard for measurements of glomerular filtration rate (GFR) in dialysis patients.

METHODS

⁵¹Cr-EDTA clearances in plasma, urine, and dialysate were evaluated in a sample of 12 hemodialysis and 12 peritoneal dialysis patients. The patients' condition was generally stable, and all patients were investigated twice within 4-10 days.

RESULTS

Plasma clearances of ⁵¹Cr-EDTA for all patients ranged between 2.1 and 30.8 mL/min/1.73 m², whereas urinary ⁵¹Cr-EDTA clearances ranged from 0.7-20.0 mL/min/1.73 m². This difference was statistically significant (p < 0.001). Week-to-week reproducibility expressed as coefficients of variation were below or equal to 10% for plasma clearances and 13% for urinary clearances in hemodialysis patients and 14% in peritoneal dialysis patients.

CONCLUSIONS

This study demonstrated a difference between ⁵¹Cr-EDTA plasma and urinary clearances in dialysis patients. Plasma clearance of ⁵¹Cr-EDTA had the best reproducibility. For repeated measurements as in clinical prospective trials, we recommend ⁵¹Cr-EDTA plasma clearance based on blood sampling at 5 + 24 hours with subtraction of ⁵¹Cr-EDTA dialysate clearance in peritoneal dialysis patients. Further studies are needed to corroborate our findings.

Early start of dialysis: a critical review

In the US, patients who initiate dialysis "early" (at Modification of Diet in Renal Disease estimated GFR [eGFR]> 10 ml/min per 1.73 m(2)) account for over 50 percent of new dialysis starts. This trend to an early start is based on conventional wisdoms regarding benefits of dialytic clearance, that albumin levels are nutritional markers, and early dialytic therapy is justified to improve nutrition especially in diabetics and that waiting until low levels of eGFR (i.e., <6 ml/min per 1.73 m(2)) may be dangerous. In order to justify early dialysis treatment, the therapy must provide a morbidity, mortality, or quality of life benefit. The current review examines whether early dialysis initiation provides any of these benefits and whether the conventional wisdoms that have promoted this early dialysis trend are valid. Utilizing this information and the results of recent large observational studies and the randomized controlled Initiating Dialysis Early and Late (IDEAL) study, we suggest that dialysis initiation is justified at GFR levels of 5-9 ml/min/1.73 m(2), if accompanied by uremia symptoms or fluid management issues.

Preservation of residual renal function with limited water removal in hemodialysis patients

Residual renal function (RRF) is of paramount importance for hemodialysis (HD) adequacy, morbidity, and mortality. Some studies have shown that overhydration is beneficial for preservation of RRF, but it can also increase the probability of adverse events such as hypertension and heart failure in HD patients. To determine the optimal amount of dehydration, we performed HD with limited water removal in HD patients. Eighteen HD patients included in this self-controlled study underwent HD with limited water removal. Water removal volume was determined by a previous volume as follows. Total water removal volume was divided into levels: ≤3.0, 3.0-9.0, and >9.0 L per week. Water removal was performed to obtain dry weight in the last dialysis, and was performed three times with a ratio of 1:1:2 and 2:2:3, respectively. Urine volume, endogenous creatinine clearance rate, Kt/V, hemoglobin, and serum albumin were recorded before and after the study at 3, 6, 9, and 12 months. The follow-up period was 12 months. Ten patients withdrew from the study because of adverse events including hypertension (n = 3), heart failure (n = 3), angina (n = 1), polycystic kidney rupture (n = 1), obvious edema (n = 1), and one patient had too much interdialytic weight gain to continue. As a result, we stopped this study after 1 month. Our data suggest that the preservation of RRF with limited water removal in HD patients must be interpreted with caution.