Impact of home-based exercise on residual kidney function in patients initiating peritoneal dialysis: A feasibility multicenter randomized controlled trial

BACKGROUND

Although the impact of aerobic exercise (AE) and resistance training (RT) on peritoneal dialysis (PD) patients is well established, the impact of exercise programs on residual kidney function (RKF) has not been elucidated.

METHODS

Patients were randomly assigned to either the exercise (n = 25) or control groups (n = 30). Patients in the exercise group performed AE three times a week and RT twice a week at home for 24 weeks. The control group did not receive any specific intervention. The primary outcome was RKF, assessed by residual glomerular filtration rate (rGFR). Secondary outcomes included urinary protein levels, distance covered in the incremental shuttle walking test (ISWT), and glycated hemoglobin (HbA1c) percentages.

RESULTS

Linear mixed-effects models showed no significant changes in mean rGFR between the exercise and control groups at 12 weeks (-0.40; 95% confidence interval (CI): -2.17, 1.36; p = 0.65) and at 24 weeks (0.65; 95% CI: -1.15, 2.45; p = 0.48). There was a trend toward improvement in mean urinary protein level and ISWT results, and a significant decrease in mean HbA1c percentage at 24 weeks in the exercise group (-1.07, 95% CI: -2.29, 0.15, p = 0.09; 37.7, 95% CI: -10.1, 85.5, p = 0.12; -0.57, 95% CI: -0.97, -0.18, p = 0.005, respectively) compared to the control group.

CONCLUSION

The 24-week home-based exercise program did not demonstrate beneficial effects on RKF in incident PD patients. Nonetheless, it may have an impact on reducing urinary protein levels and HbA1c percentages.

Early Anuria in Incident Peritoneal Dialysis Patients: Incidence, Risk Factors, and Associated Clinical Outcomes

Rationale & Objective

The development of anuria has been linked to worse clinical outcomes in patients undergoing peritoneal dialysis (PD). Our objective was to investigate the incidence, risk factors, and associated clinical outcomes of anuria within the first year after starting PD.

Study Design

Retrospective cohort study.

Setting & Participants

Patients who started continuous ambulatory peritoneal dialysis at our center between 2006 and 2020 were included and followed up until January 31, 2023.

Exposure

Age, sex, diabetes, temporary hemodialysis, angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II receptor blockers (ARBs), diuretics, baseline urine volume, serum albumin, daily glucose exposure, peritonitis, and incremental PD.

Outcomes

The primary outcome was early anuria, defined as 24-hour urine volume ≤100 mL within the first year of PD initiation. Secondary outcomes included all-cause mortality, cardiovascular disease mortality, technique failure, and peritonitis.

Analytical Approach

Cox proportional hazards model.

Results

A total of 2,592 patients undergoing continuous ambulatory peritoneal dialysis aged 46.7 ± 14.9 years were recruited. Among them, 58.9% were male, and 24.0% had diabetes. Within the first year of PD therapy, 159 (6.13%) patients developed anuria, with a median duration of 7.53 (interquartile range, 3.93-10.0) months. Higher baseline urine volume (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.90-0.97), higher serum albumin (HR, 0.92; 95% CI, 0.88-0.95), having diabetes before PD (HR, 0.57; 95% CI, 0.35-0.92), and prescribed incremental PD (HR, 0.27; 95% CI, 0.14-0.51) were associated with a reduced risk for early anuria, whereas a higher level of daily glucose exposure (HR, 1.01; 95% CI, 1.00-1.01) was identified as a risk factor for early anuria. Subgroup analyses showed that using ACEis or ARBs was linked to a lower risk of early anuria (HR, 0.25; 95% CI, 0.09-0.69) in diabetic patients. Treating early anuria as a time-dependent covariate, early anuria was associated with a higher risk for all-cause mortality (HR, 1.69; 95% CI, 1.23-2.32) and technique failure (HR, 1.43; 95% CI, 1.00-2.04) after adjusting for confounding factors.

Limitations

Single-center and observational study.

Conclusions

Among PD patients at a single center in China, early anuria was relatively uncommon but associated with an increased risk of mortality and PD technique failure. Incremental PD, higher baseline urine output and serum albumin, and lower daily glucose exposure were associated with a lower risk of early anuria. Clinical trials are needed to evaluate the optimal PD techniques to preserve residual kidney function and maximaze outcomes.

The relationship between decline rate of residual renal function in the first year and mortality in peritoneal dialysis patients

INTRODUCTION

To assess the relationship between the rate of residual renal function (RRF) decline in the first year and all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

METHODS

Incident PD patients were divided into two groups by the corresponding RRF decline value, when hazard ratio (HR) = 1 was found by the restricted cubic spline. The associations of rate of decline of RRF in the first year with mortality were evaluated.

RESULTS

Of 497 PD patients, 122 patients died. After adjusting for confounding factors, patients in fast-decline group had a significant increase risk of all-cause and cardiovascular mortality (HR: 1.97 and 2.09, respectively). Each 0.1-mL/min/1.73 m2 /month decrease in RRF in the first year of PD was associated with a 19% and 20% higher risk of all-cause and cardiovascular mortality, respectively.

CONCLUSIONS

Faster decline of RRF in the first year was independently associated with all-cause and cardiovascular mortality in PD patients.

Influencing factors for residual kidney function in incident peritoneal dialysis patients: a systematic review and meta-analysis

BACKGROUND

Residual kidney function (RKF) impacts patients' survival rate and quality of life when undergoing peritoneal dialysis (PD). This meta-analysis was conducted to systematically identify risk and protective factors associated with RKF decline and loss.

METHODS

We searched three English and one Chinese databases from inception to January 31, 2023, for cohort and cross-sectional studies exploring factors associated with RKF decline or loss. The random effects model was employed to aggregate risk estimates and 95% confidence intervals (CIs) from multivariate analysis. Sensitivity and subgroup analyses were performed to explore the heterogeneity among the studies.

RESULTS

Twenty-seven studies comprising 13549 individuals and 14 factors were included in the meta-analysis. Based on the meta-analysis results, risk factors involving male gender (hazard ratio (HR) 1.689, 95%CI 1.385-2.061), greater body mass index (BMI) (odds ratio (OR) 1.081, 95% confidence interval (CI) 1.029-1.135), higher systolic blood pressure (SBP) (HR 1.014, 95%CI 1.005-1.024), diabetes mellitus (DM) (HRRKF loss 1.873, 95%CI 1.475-2.378), DM (ORRKF decline 1.906, 95%CI 1.262-2.879), peritonitis (relative ratio (RR) 2.291, 95%CI 1.633-3.213), proteinuria (OR 1.223, 95%CI 1.117-1.338), and elevated serum phosphorus (RR 2.655, 95%CI 1.679-4.201) significantly contributed to the risk of RKF decline and loss in PD patients. Conversely, older age (HR 0.968, 95%CI 0.956-0.981), higher serum albumin (OR 0.834, 95%CI 0.720-0.966), weekly Kt/V urea (HR 0.414, 95%CI 0.248-0.690), baseline urine volume (UV) (HR 0.791, 95%CI 0.639-0.979), baseline RKF (HR 0.795, 95%CI 0.739-0.857) exhibited protective effects. However, diuretics use, automatic peritoneal dialysis (APD) modality and baseline RKF did not significantly impact RKF decline.

CONCLUSIONS

Patients with male gender, greater BMI, higher SBP, DM, peritonitis, proteinuria, and elevated serum phosphorus might have a higher risk of RKF decline and loss. In contrast, older age, higher serum albumin, weekly Kt/V urea, baseline UV, and baseline RKF might protect against RKF deterioration.

Urine volume as an estimator of residual renal clearance and urinary removal of solutes in patients undergoing peritoneal dialysis

In non-anuric patients undergoing peritoneal dialysis (PD), residual kidney function (RKF) is a main contributor to fluid and solute removal and an independent predictor of survival. We investigated if urine volume could be used to estimate renal clearances and removal of urea, creatinine, and phosphorus in PD patients. The observational, cross-sectional study included 93 non-anuric prevalent PD patients undergoing continuous ambulatory PD (CAPD; n = 34) or automated PD (APD; n = 59). Concentrations of urea, creatinine and phosphorus in serum and in 24-h collections of urine volume were measured to calculate weekly residual renal clearance (L/week) and removed solute mass (g/week). Median [interquartile range], 24-h urine output was 560 [330-950] mL and measured GFR (the mean of creatinine and urea clearances) was 3.24 [1.47-5.67] mL/min. For urea, creatinine and phosphorus, residual renal clearance was 20.60 [11.49-35.79], 43.02 [19.13-75.48] and 17.50 [8.34-33.58] L/week, respectively, with no significant differences between CAPD and APD. Urine volume correlated positively with removed solute masses (rho = 0.82, 0.67 and 0.74) and with weekly residual renal clearances (rho = 0.77, 0.62 and 0.72 for urea, creatinine, and phosphorus, respectively, all p < 0.001). Residual renal clearances and urinary mass removal rates for urea, creatinine, and phosphorus correlate strongly with 24-h urine volume suggesting that urine volume could serve as an estimator of typical values of residual solute removal indices in PD patients.

Association of single and serial measures of serum phosphorus with adverse outcomes in patients on peritoneal dialysis: results from the international PDOPPS

BACKGROUND

While high serum phosphorus levels have been related to adverse outcomes in hemodialysis patients, further investigation is warranted in persons receiving peritoneal dialysis (PD).

METHODS

Longitudinal data (2014-17) from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS), a prospective cohort study, were used to examine associations of serum phosphorus with all-cause mortality and major adverse cardiovascular events via Cox regression adjusted for confounders. Serum phosphorus levels were parameterized by four methods: (i) baseline serum phosphorus; (ii) mean 6-month serum phosphorus; (iii) number of months with serum phosphorus >4.5 mg/dL; and (iv) mean area-under-the-curve of 6-month serum phosphorus control.

RESULTS

The study included 5847 PD patients from seven countries; 9% of patients had baseline serum phosphorus <3.5 mg/dL, 24% had serum phosphorus ≥3.5 to ≤4.5 mg/dL, 30% had serum phosphorus >4.5 to <5.5 mg/dL, 20% had serum phosphorus ≥5.5 to <6.5 mg/dL, and 17% had serum phosphorus ≥6.5 mg/dL. Compared with patients with baseline serum phosphorus ≥3.5 to ≤4.5 mg/dL, the adjusted all-cause mortality hazard ratio (HR) was 1.19 (0.92,1.53) for patients with baseline serum phosphorus ≥5.5 to <6.5 mg/dL and HR was 1.53 (1.14,2.05) for serum phosphorus ≥6.5 mg/dL. Associations between serum phosphorus measurements over 6 months and clinical outcomes were even stronger than for a single measurement.

CONCLUSIONS

Serum phosphorus >5.5 mg/dL was highly prevalent (37%) in PD patients, and higher serum phosphorus levels were a strong predictor of morbidity and death, particularly when considering serial phosphorus measurements. This highlights the need for improved treatment strategies in this population. Serial serum phosphorus measurements should be considered when assessing patients' risks of adverse outcomes.

The spectrum of kidney dysfunction requiring chronic dialysis therapy: Implications for clinical practice and future clinical trials

Staging to capture kidney function and pathophysiologic processes according to severity is widely used in chronic kidney disease or acute kidney injury not requiring dialysis. Yet the diagnosis of "end-stage kidney disease" (ESKD) considers patients as a single homogeneous group, with negligible kidney function, in need of kidney replacement therapy. Herein, we review the evidence behind the heterogeneous nature of ESKD and discuss potential benefits of recasting the terminology used to describe advanced kidney dysfunction from a monolithic entity to a disease with stages of ascending severity. We consider kidney assistance therapy in lieu of kidney replacement therapy to better reconcile all available types of therapy for advanced kidney failure including dietary intervention, kidney transplantation, and dialysis therapy at varied schedules. The lexicon "kidney dysfunction requiring dialysis" (KDRD) with stages of ascending severity based on levels of residual kidney function (RKF)-that is, renal urea clearance-and manifestations related to uremia, fluid status, and other abnormalities is discussed. Subtyping KDRD by levels of RKF could advance dialysis therapy as a form of kidney assistance therapy adjusted based on RKF and clinical symptoms. We focus on intermittent hemodialysis and underscore the need to personalize dialysis treatments and improve characterization of patients included in clinical trials.

Association of blood pressure after peritoneal dialysis initiation with the decline rate of residual kidney function in newly-initiated peritoneal dialysis patients

Background

Lower blood pressure (BP) levels are linked to a slower decline of kidney function in patients with chronic kidney disease (CKD) without kidney replacement therapy. However, there are limited data on this relation in peritoneal dialysis (PD) patients. Here we evaluated the association of BP levels with the decline of residual kidney function (RKF) in a retrospective cohort study.

Methods

We enrolled 228 patients whose PD was initiated between 1998 and 2014. RKF was measured as the average of creatinine and urea clearance in 24-hr urine collections. We calculated the annual decline rate of RKF by determining the regression line for individual patients. RKF is thought to decline exponentially, and thus we also calculated the annual decline rate of logarithmic scale of RKF (log RKF). We categorized the patients’ BP levels at 3 months after PD initiation (BP_3M) into four groups (Optimal, Normal & High normal, Grade 1 hypertension, Grade 2 & 3 hypertension) according to the 2018 European Society of Cardiology and European Society of Hypertension Guidelines for the management of arterial hypertension.

Results

The unadjusted, age- and sex-adjusted, and multivariable-adjusted decline rate of RKF and log RKF decreased significantly with higher BP_3M levels (P for trend <0.01). Compared to those of the Optimal group, the multivariable-adjusted odds ratios (95% confidence interval) for the faster side of the median decline rate of RKF and log RKF were 4.04 (1.24–13.2) and 5.50 (1.58–19.2) in the Grade 2 and 3 hypertension group, respectively (p<0.05).

Conclusions

Higher BP levels after PD initiation are associated with a faster decline in RKF among PD patients.

Association of Urinary Dickkopf-3 with Residual Renal Function Decline in Patients Undergoing Peritoneal Dialysis

Background and Objectives: Urinary levels of dickkopf-3 (DKK-3) are associated with poor renal survival in patients with non-dialytic chronic kidney disease. However, it remains unknown whether urinary DKK-3 levels can predict residual renal function (RRF) decline in patients undergoing peritoneal dialysis (PD). Therefore, we investigated the correlation between urinary levels of DKK-3 and the subsequent rate of RRF decline in PD patients. Materials and Methods: This study included 36 PD patients who underwent multiple peritoneal equivalent tests during 2011–2021. The relationship between baseline clinical characteristics and the subsequent annual rate of Kt/V decline was investigated. Results: The annual rate of renal Kt/V decline was 0.29 (range: 0.05–0.48), which correlated with renal Kt/V (r = 0.55, p = 0.0005) and 24 h urinary DKK-3 excretion (r = 0.61, p < 0.0001). Similarly, 24 h urinary DKK-3 excretion (β = 0.44, p = 0.0015) and renal Kt/V (β = 0.38, p = 0.0059) were independently associated with the annual rate of renal Kt/V decline in multivariate analyses. Conclusions: Urinary DKK-3 assessment may help identify PD patients at a high risk of RRF decline.

Risk factors for mortality in patients undergoing peritoneal dialysis: a systematic review and meta-analysis

Aim

Inconsistent investigations of the risk factors for all-cause mortality in patients undergoing peritoneal dialysis (PD) were reported. The present meta-analysis aimed to assess the impact of some clinical characteristics on the risk of mortality in PD patients.

Methods

PubMed and Embase were systematically searched for studies evaluating the risk factors for all-cause mortality in PD patients. Hazard ratio (HR) and 95% confidence interval (CI) were derived using a random-effect or fixed-effect model considering the heterogeneity across studies.

Result

A total of 26 studies were included in this meta-analysis in accordance with the inclusion and exclusion criteria. Age, primary cardiovascular diseases, diabetes mellitus, and high level of alkaline phosphatase showed significant positive associations with elevated risk of all-cause and cardiovascular mortality in PD patients, while hemoglobin acted as a benefit factor. Furthermore, early onset of peritonitis, high peritoneal transport status, elevated body mass index and high-sensitivity C-reactive protein could also considerably increase the risk of all-cause mortality. The absolute serum level of magnesium, potassium, and uric acid required to improve survival in PD patients should be verified further.

Conclusions

Multiple factors could affect the risk of mortality in PD patients.

Rate of decline in residual kidney function pre and post peritoneal dialysis initiation: A post hoc analysis of the IDEAL study

Background

Residual kidney function (RKF) is associated with improved survival and quality of life in dialysis patients. Previous studies have suggested that initiation of peritoneal dialysis (PD) may slow RKF decline compared to the pre-dialysis period. We sought to evaluate the association between PD initiation and RKF decline in the Initiating Dialysis Early And Late (IDEAL) trial.

Methods

In this post hoc analysis of the IDEAL randomized controlled trial, PD participants were included if results from 24-hour urine collections had been recorded within 30 days of dialysis initiation, and at least one value pre- and one value post-dialysis commencement were available. The primary outcome was slope of RKF decline, calculated as mean of urinary creatinine and urea clearances. Secondary outcomes included slope of urine volume decline and time from PD initiation to anuria.

Results

The study included 151 participants (79 early start, 72 late start). The slope of RKF decline was slower after PD initiation (-2.69±0.18mL/min/1.73m²/yr) compared to before PD (-4.09±0.33mL/min/1.73m²/yr; change in slope +1.19 mL/min/1.73m²/yr, 95%CI 0.48–1.90, p<0.001). In contrast, urine volume decline was faster after PD commencement (-0.74±0.05 L/yr) compared to beforehand (-0.57±0.06L/yr; change in slope -0.18L/yr, 95%CI -0.34—-0.01, p = 0.04). No differences were observed between the early- and late-start groups with respect to RKF decline, urine volume decline or time to anuria.

Conclusions

Initiation of PD was associated with a slower decline of RKF compared to the pre-dialysis period.

What is the Optimal Fat Mass in Peritoneal Dialysis Patients?

The prevalence of obesity in peritoneal dialysis (PD) populations has risen dramatically since the mid-1980s. This epidemic has been driven by the increased prevalence of obesity in the general population, the increased risk of progression of chronic kidney disease to end-stage renal failure (ESRF) in obese subjects, the reduced probability of listing obese dialysis patients for renal transplantation, a paradoxical enhanced survival in at least some obese populations on dialysis as compared with non-obese ESRF patients, and a possible adipogenic effect of excessive peritoneal glucose absorption in PD. Although obesity has consistently been associated with improved outcomes in hemodialysis, conflicting results have been seen in PD. In general, an elevated body mass index (BMI) has been associated with a neutral or deleterious impact on PD outcomes, and the relationship appears to be explained predominantly by fat mass. Risk is also elevated in patients with a low BMI, such that the “optimal BMI” appears to lie between 20 kg/m2 and 25 kg/m2. The mechanisms underpinning the harmful effect of obesity appear to include increased peritonitis rate, proinflammatory effects, and a more rapid decline of residual renal function in obese patients. No proof exists that weight reduction engenders an improvement in outcome in PD patients, but the available studies suggest that cautious weight reduction is advisable. A few studies have demonstrated that clinically important and sustained weight reduction can be successfully achieved through a combination of individual meal plans, regular exercise, and substitution of icodextrin for dextrose in the once-daily long dwell.

Continuous Ambulatory Peritoneal Dialysis is Better than Automated Peritoneal Dialysis as First-Line Treatment in Renal Replacement Therapy

This article examines the roles of continuous ambulatory peritoneal dialysis (CAPD) versus automated peritoneal dialysis (APD) as first-line renal replacement therapy. To date, no high-quality large-scale randomized controlled studies have compared CAPD with APD as first-line therapy. However, a discussion on this issue is important so that nephrologists can decide and patients can have a choice of modality on which to start dialysis, especially in the context of health care economics. We review the literature and present Hong Kong as the model of a “CAPD first” policy, an appealing, cost-effective approach for any country.

An ideal renal replacement therapy should provide optimal survival, lowest possible risk for comorbidity, highest level of quality of life, and equally important, acceptable cost to society. When we consider this subject in the context that all patients should be started on one first-line modality, the data suggest that a “CAPD first” policy has all these advantages, with APD probably having the edge only with regard to patient preference. The present review highlights preservation of residual renal function, removal and balancing of sodium, incidence of peritonitis, peritoneal membrane transport status, patient rehabilitation, and financial issues in demonstrating that a “CAPD first” policy is the model that should be adopted.

Predictors of Faster Decline of Residual Renal Function in Taiwanese Peritoneal Dialysis Patients

⋄ Objective

Loss of residual renal function (RRF) in peritoneal dialysis (PD) patients is a powerful predictor of mortality. The present study was conducted to determine the predictors of faster decline of RRF in PD patients in Taiwan.

⋄ Methods

The study enrolled 270 patients starting PD between January 1996 and December 2005 in a single hospital in Taiwan. We calculated RRF as the mean of the sum of 24-hour urea and creatinine clearance. The slope of the decline of residual glomerular filtration rate (GFR) was the main outcome measure. Data on demographic, clinical, laboratory, and treatment parameters; episodes of peritonitis; and hypotensive events were analyzed by Student t-test, Mann–Whitney U-test, and chi-square, as appropriate. All variables with statistical significance were included in a multivariate linear regression model to select the best predictors ( p < 0.05) for faster decline of residual GFR.

⋄ Results

All patients commencing PD during the study period were followed for 39.4 ± 24.0 months (median: 35.5 months). The average annual rate of decline of residual GFR was 1.377 ± 1.47 mL/min/m2. On multivariate analysis, presence of diabetes mellitus ( p < 0.001), higher baseline residual GFR ( p < 0.001), hypotensive events ( p = 0.001), use of diuretics ( p = 0.002), and episodes of peritonitis ( p = 0.043) independently predicted faster decline of residual GFR. Male sex, old age, larger body mass index, and presence of coronary artery disease or congestive heart failure were also risk factors on univariate analysis.

⋄ Conclusions

Our results suggested that diabetes mellitus, higher baseline residual GFR, hypotensive events, and use of diuretics are independently associated with faster decline of residual GFR in PD patients in Taiwan.

Impact of obesity on the evolution of outcomes in peritoneal dialysis patients

Background

Some studies reveal that obesity is associated with a decrease in mortality in haemodialysis (HD) patients. However, few studies have addressed the association between body mass index (BMI) and peritoneal dialysis (PD) patients.

Methods

We performed this longitudinal, retrospective study to evaluate the impact of obesity on PD patients, using data from the Catalan Registry of Renal Patients from 2002 to 2015 (n = 1573). Obesity was defined as BMI ≥30; low weight: BMI <18.5; normal range: BMI = 18.5–24.99; and pre-obesity: BMI = 25–29.99 kg/m². Variations in BMI were calculated during follow-up. The main outcomes evaluated were the technique and patient survival.

Results

Obesity was observed in 20% of patients starting PD. We did not find differences in sex or PD modality, with the obesity group being older (65.9% are ≥55 years versus 59% non-obese, P = 0.003) and presenting more diabetes mellitus and cardiovascular disease (CVD) (47.9% obese versus 25.1% non-obese and 41.7% versus 31.5%, respectively). We did not observe differences in haemoglobin, albumin and Kt/V in obese patients. Regarding peritonitis rate, we did not find any difference between groups, presenting more peritonitis patients on continuous ambulatory peritoneal dialysis and aged ≥65 years [sub-hazard ratio (SHR) = 1.75, P = 0.000 and SHR = 1.56, P = 0.009]. In relation to technique survival, we found higher transfer to HD in the obese group of patients in the univariate analysis, which was not confirmed in the multivariate analysis (SHR = 1.12, P = 0.4), and we did not find differences in mortality rate. In relation to being transplanted, the underweight group, elderly and patients with CVD or diabetic nephropathy presented less probability to undergo kidney transplantation (SHR = 0.65, 0.24, 0.5 and 0.54, P < 0.05). Obese patients did not present differences in survival with weight changes but in normal-weight patients, a gain of 7% of the basal weight during the first year had a protective effect on death risk (hazard ratio 0.6, P = 0.034).

Conclusions

Obese and non-obese patients starting on PD had similar outcomes.

Obesity is a Risk Factor for Peritonitis in the Australian and New Zealand Peritoneal Dialysis Patient Populations

Objective

The aim of the present investigation was to examine the association between body mass index (BMI) and peritonitis rates among incident peritoneal dialysis (PD) patients in a large cohort with long-term follow-up.

Design

Retrospective observational cohort study of the Australian and New Zealand PD patient population.

Setting

Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry.

Participants

The study included all incident adult patients ( n = 10 709) who received PD in Australia and New Zealand in the 12-year period between 1 April 1991 and 31 March 2003. Patients were classified as obese (BMI ≥ 30 kg/m2), overweight (BMI 25.0 – 29.9 kg/m2), normal weight (20 – 24.9 kg/m2), or underweight (< 20 kg/m2).

Main Measurements

Time to first peritonitis and episodes of peritonitis per patient-year were recorded over the 12-year period.

Results

Higher BMI was associated with a shorter time to first peritonitis episode, independent of other risk factors [hazard ratio 1.08 for each 5-kg/m2increase in BMI, 95% confidence interval (CI) 1.04 – 1.12, p < 0.001]. When peritonitis outcomes were analyzed as episodes of peritonitis per patient-year, these rates were significantly higher among patients with higher BMI: underweight 0.69 episodes/year (95% CI 0.66 – 0.73), normal weight 0.79 (95% CI 0.77 – 0.81), overweight 0.88 (95% CI 0.85 – 0.90), obese 1.06 (95% CI 1.02 – 1.09). Coronary artery disease and chronic lung disease were associated with both shorter time to first peritonitis and higher peritonitis rates, independently of these other factors. There was also a “vintage effect,” with lower peritonitis rates seen among people who commenced dialysis in more recent years.

Conclusions

Higher BMI at the commencement of renal replacement therapy is a significant risk factor for peritonitis. The mechanisms for this remain undefined.

Automated Peritoneal Dialysis Has Significant Effects on Systemic Hemodynamics

Objectives

Maintenance of residual renal function (RRF) is an important determinant of outcome in peritoneal dialysis patients. It remains contentious as to whether automated peritoneal dialysis (APD) leads to an increased rate of decline of RRF compared with continuous ambulatory peritoneal dialysis (CAPD). We studied whether APD was associated with significant systemic hemodynamic changes that may play a role in the accelerated loss of RRF.

Methods

As a follow-on from a previous study, 8 well-established CAPD patients underwent a 4-hour APD treatment consisting of 3 drain/fill cycles using 2 x 2.5 L 1.36% glucose and 1 x 3.86% glucose dialysate. Each dwell phase lasted 76 minutes. Blood pressure (BP) and a full range of hemodynamic variables, including pulse (HR), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR), were measured noninvasively using continuous arterial pulse wave analysis.

Results

BP fell during 2 of the 3 drain/fill periods when dialysate was drained from the peritoneal cavity, but then rose upon instillation of dialysate fluid. The fall in BP was associated with a fall in TPR, matched by an inadequate rise in SV and CO. Over the entire study period, TPR progressively rose to +53.4% above baseline ( p = 0.032). Both SV and CO fell over the same period, to -21.1% ( p = 0.060) and -22.4% from baseline ( p = 0.037) respectively. This did not result in any significant difference between start and end BP.

Conclusions

This study demonstrates that APD is associated with significant systemic hemodynamic effects. The increased number of drain/fill cycles compared to CAPD, or the progressive rise in TPR and reduction in CO (possibly due to a cooling effect), may potentially be factors that adversely affect RRF in APD patients.

The Fate of Older Diabetic Patients on Peritoneal Dialysis: Myths and Mysteries and Suggestions for Further Research

The outcome of older and especially of female diabetic patients appears to be worse on peritoneal dialysis (PD) than on hemodialysis (HD). This opinion is based mostly on data coming from the USA, whereas data from other regions seem to give a more balanced picture. The questions arise whether indeed outcome is worse in this patient group, and what might be the underlying reasons for this; further research to unravel this phenomenon is warranted. This review proposes several suggestions for further exploration. The observed differences in outcome might be attributable to differences in treatment practices and experience with PD versus HD. As cardiovascular mortality is a major killer in end-stage renal disease patients, differences in fluid homeostasis and how it is achieved are potential explanations. Fluid balance is potentially more difficult to obtain in PD patients, especially as in the past it was spuriously suggested that fluid restriction was less important in PD patients. PD and HD might also have different impacts on factors related to inflammation, insulin resistance, and hormone balance. The adipocytokine network is of special interest in this respect. It is also possible that bias introduced by the way we measure body composition might have a more negative impact on PD than on HD patients. Finally, it still is not fully established that if diabetic patients are treated appropriately, their outcome on PD is worse than that on HD; further observational trials in this respect are needed. All these topics require further clarification and investigation.

Predictors of Renal Recovery in Australian and New Zealand end-Stage Renal Failure Patients Treated with Peritoneal Dialysis

Objectives

The aim of this study was to investigate the factors affecting recovery and durability of dialysis-independent renal function following commencement of peritoneal dialysis (PD).

Design

Retrospective, observational cohort study of the Australian and New Zealand PD patient population.

Setting

Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry.

Participants

The study reviewed all patients in Australia and New Zealand who commenced PD for treatment of end-stage renal failure between 15 May 1963 and 31 December 2004.

Main Outcome Measures

The primary outcomes examined were recovery of dialysis-independent renal function and time from PD commencement to recovery of renal function. A secondary outcome measure was time to renal death (patient death or recommencement of renal replacement therapy) following recovery of dialysis-independent renal function.

Results

24663 patients commenced PD during the study period. Of these, 253 (1%) recovered dialysis-independent renal function. An increased likelihood of recovery was predicted by autoimmune renal disease, hemolytic-uremic syndrome, paraproteinemia, cortical necrosis, renovascular disease, and treatment in New Zealand. A reduced likelihood of recovery was associated with polycystic kidney disease and indigenous race. Analysis of a contemporary subset of 14743 patients in whom complete data were available for body mass index, smoking, and comorbidities yielded comparable results, except that increasing age was additionally associated with a decreased likelihood of recovery. Of the 253 patients who recovered renal function, 151 (60%) recommenced renal replacement therapy and 49 (19%) died within a median period of 226 days (interquartile range 110 – 581 days). The only significant predictors of continued renal survival after renal recovery were autoimmune renal disease and cortical necrosis.

Conclusions

Recovery of renal function in patients treated with PD is rare and determined mainly by renal disease type and race. In the majority of cases, recovery is short term. The apparently high rate of early patient death or return to dialysis after recovery of renal function on PD raises questions about the appropriateness of discontinuing PD therapy under such circumstances.

Effects of volume status on body composition in incident peritoneal dialysis patients

BACKGROUND

Inadequate fluid removal or high water intake leads to overhydration, which results in malnutrition. The aim of the present study was to evaluate the effects of volume status on body composition in incident peritoneal dialysis (PD) patients.

METHODS

All incident PD patients who survived ≥1 year after PD initiation were considered eligible. A total of 366 incident PD patients were finally included and divided into three tertiles according to the time-averaged-edema index (TA-EI). The body composition parameters measured using bioimpedance analysis included the EI, fat mass index (FMI, kg/m²), and appendicular muscle mass index (AMMI, kg/m²). dFMI and dAMMI were defined as delta values for each variable. The cutoff value for sarcopenia (SP) was defined as previously reported. Patients with AMMI below the cutoff values were defined as having SP.

RESULTS

The number of participants in the low, middle, and high tertiles was 126, 100, and 140, respectively. A high volume status was associated with high solute clearance, albumin loss, and glucose absorption through the peritoneal membrane, which led to high dialysate glucose. In addition, volume status was inversely associated with increases in AMMI, but was not associated with changes in FMI. SP as a categorical variable was positively associated with a high volume status. On subgroup analyses, TA-EI had the greatest negative correlation coefficients for dAMMI.

CONCLUSION

Overhydration in PD patients was associated with decrease in muscle mass indices and the development of SP.

Effectiveness of Renin-Angiotensin-Aldosterone System Blockade on Residual Kidney Function and Peritoneal Membrane Function in Peritoneal Dialysis Patients: A Network Meta-Analysis

We performed a network meta-analysis of randomised controlled trials (RCTs) and non-randomised studies in adult peritoneal dialysis patients to evaluate the effects of specific renin-angiotensin aldosterone systems (RAAS) blockade classes on residual kidney function and peritoneal membrane function. Key outcome parameters included the following: residual glomerular filtration rate (rGFR), urine volume, anuria, dialysate-to-plasma creatinine ratio (D/P Cr), and acceptability of treatment. Indirect treatment effects were compared using random-effects model. Pooled standardised mean differences (SMDs) and odd ratios (ORs) were estimated with 95% confidence intervals (CIs). We identified 10 RCTs (n = 484) and 10 non-randomised studies (n = 3,305). Regarding changes in rGFR, RAAS blockade with angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) were more efficacious than active control (SMD 0.55 [0.06-1.04] and 0.62 [0.19-1.04], respectively) with the protective effect on rGFR observed only after usage ≥12 months, and no differences among ACEIs and ARBs. Compared with active control, only ACEIs showed a significantly decreased risk of anuria (OR 0.62 [0.41-0.95]). No difference among treatments for urine volume and acceptability of treatment were observed, whereas evidence for D/P Cr is inconclusive. The small number of randomised studies and differences in outcome definitions used may limit the quality of the evidence.

High rates of protein intake are associated with an accelerated rate of decline of residual kidney function in incident peritoneal dialysis patients

BACKGROUND

Preservation of residual kidney function (RKF) is a relevant objective in peritoneal dialysis (PD) patients. The influence of dietary protein intake (PI) on this variable has not been adequately investigated.

METHODS

Following an observational design, we studied 336 patients incident on PD, with a minimum follow-up of 6 months. The main study variable was the mean PI [normalized rate of protein nitrogen appearance (nPNA)] during the first 4 months on PD. The main outcome variables were the absolute rate of decline of RKF and the proportion of patients presenting a >50% decay of their RKF during the first year of follow-up. We applied univariate and multivariate strategies of analysis, taking into consideration the main control variables bearing a correlation with nPNA and/or RKF.

RESULTS

Mean nPNA (first 4 months) was 1.23 ± 0.33 g/kg/day, while the overall rate of decline of RKF was -0.13 ± 0.29 mL/min/month; 69 patients (25.1%) had lost >50% of their initial RKF by the end of the first year. Univariate analysis disclosed consistent associations between the main study variable on one hand and baseline RKF (r = 0.32, P < 0.0005) and its rate of decline (r = -0.23, P < 0.0005) on the other. The latter two variables were also significantly correlated (r = -0.36, P < 0.0005). Multivariate analysis identified mean nPNA as an independent predictor of the rate of decline of RKF [odds ratio 1.09 per 0.10 g/kg/day, 95% confidence interval (CI) 0.99-1.19, P = 0.058] and, in particular, of the probability of losing >50% of the baseline RKF during the first year of treatment (odds ratio 1.15 per 0.10 g/kg/day, 95% CI 1.04-1.27, P = 0.006).

CONCLUSION

Higher rates of PI during the first months of therapy are associated with a faster decline of RKF among patients incident on PD. Our results underline the convenience of keeping an adequate balance between sufficient protein ingestion, to prevent malnutrition and wasting, and sensible restriction in stable, adequately nourished individuals with rates of intake in the higher range or above-recommended allowances.

Impact of body mass index on survival in patients undergoing peritoneal dialysis: Analysis of data from the Insan Memorial End-Stage Renal Disease Registry of Korea (1985-2014)

Background

Significant increases in the prevalence of obesity have been observed among patients with peritoneal dialysis (PD). The impact of body mass index (BMI) on survival remains unknown in Korean PD patients.

Methods

Among data of 80,674 patients on PD acquired from the Insan Memorial ESRD Registry database for the years 1985 to 2014, 6,071 cases were analyzed. Subjects were classified by baseline BMI; < 21.19 kg/m² (quartile 1, n = 1,518), 21.19 to 23.18 kg/m² (quartile 2, reference; n = 1,453), 23.19 to 25.71 kg/m² (quartile 3, n = 1,583), and > 25.71 kg/m² (quartile 4, n = 1,517).

Results

Mean age was 65.8 years, and baseline BMI was 23.57 kg/m². Numbers of male and diabetic patients were 3,492 (57.5%) and 2,192 (36.1%), respectively. Among 6,071 cases, 2,229 (36.7%) all-cause deaths occurred. As a whole, Kaplan–Meier survival curves according to BMI quartiles was significantly different (P = 0.001). All-cause mortality was significantly higher in quartile 4 than in the reference (hazard ratio [HR] = 1.154, 95% confidence interval [CI], 1.025–1.300; P = 0.018). There was no statistical difference in all-cause mortality among BMI quartiles in diabetic patients on PD. In non-diabetic patients, all-cause mortality of quartiles 1 and 3 was not different from the reference, but the HR was 1.176 times higher in quartile 4 (95% CI, 1.024–1.350; P = 0.022).

Conclusion

Baseline BMI > 25.71 kg/m² seems to be an important risk factor for all-cause mortality in Korean PD patients.

The Effect of Automated versus Continuous Ambulatory Peritoneal Dialysis on Mortality Risk in China

Background

There is an emerging practice pattern of automated peritoneal dialysis (APD) in China. We report on outcomes compared to continuous ambulatory peritoneal dialysis (CAPD) in a Chinese cohort.

Methods

Data were sourced from the Baxter Healthcare (China) Investment Co. Ltd Patient Support Program database, comprising an inception cohort commencing PD between 1 January 2005 and 13 August 2015. We used time-dependent cause-specific Cox proportional hazards and Fine-Gray competing risks (kidney transplantation, change to hemodialysis) models to estimate relative mortality risk between APD and CAPD. We adjusted or matched for age, gender, employment, insurance, primary renal disease, size of PD program, and year of dialysis inception. We used cluster robust regression to account for center effect.

Results

We modeled 100,351 subjects from 1,178 centers over 240,803 patient-years. Of these, 368 received APD at some time. Compared with patients on CAPD, those on APD were significantly younger, more likely to be male, employed, self-paying, and from larger programs. Overall, APD was associated with a hazard ratio (HR) for death of 0.79 (95% confidence interval [CI] 0.64 – 0.97) compared with CAPD in Cox proportional hazards models, and 0.76 (0.62 – 0.95) in Fine-Gray competing risks regression models. There was prominent effect modification by follow-up time: benefit was observed only up to 4 years follow-up, after which risk of death was similar.

Conclusion

Automated peritoneal dialysis is associated with an overall lower adjusted risk of death compared with CAPD in China. Analyses are limited by the likelihood of important selection bias arising from group imbalance, and residual confounding from unavailability of important clinical covariates such as comorbidity and Kt/V.

Impact of Obesity on Modality Longevity, Residual Kidney Function, Peritonitis, and Survival Among Incident Peritoneal Dialysis Patients

BACKGROUND

The prevalence of severe obesity, often considered a contraindication to peritoneal dialysis (PD), has increased over time. However, mortality has decreased more rapidly in the PD population than the hemodialysis (HD) population in the United States. The association between obesity and clinical outcomes among patients with end-stage kidney disease remains unclear in the current era.

STUDY DESIGN

Historical cohort study.

SETTING & PARTICIPANTS

15,573 incident PD patients from a large US dialysis organization (2007-2011).

PREDICTOR

Body mass index (BMI).

OUTCOMES

Modality longevity, residual renal creatinine clearance, peritonitis, and survival.

RESULTS

Higher BMI was significantly associated with shorter time to transfer to HD therapy (P for trend < 0.001), longer time to kidney transplantation (P for trend < 0.001), and, with borderline significance, more frequent peritonitis-related hospitalization (P for trend = 0.05). Compared with lean patients, obese patients had faster declines in residual kidney function (P for trend < 0.001) and consistently achieved lower total Kt/V over time (P for trend < 0.001) despite greater increases in dialysis Kt/V (P for trend < 0.001). There was a U-shaped association between BMI and mortality, with the greatest survival associated with the BMI range of 30 to < 35kg/m2 in the case-mix adjusted model. Compared with matched HD patients, PD patients had lower mortality in the BMI categories of < 25 and 25 to < 35kg/m2 and had equivalent survival in the BMI category ≥ 35kg/m2 (P for interaction = 0.001 [vs < 25 kg/m2]). This attenuation in survival difference among patients with severe obesity was observed only in patients with diabetes, but not those without diabetes.

LIMITATIONS

Inability to evaluate causal associations. Potential indication bias.

CONCLUSIONS

Whereas obese PD patients had higher risk for complications than nonobese PD patients, their survival was no worse than matched HD patients.

Rapid Change in Residual Renal Function Decline Is Associated with Lower Survival and Worse Residual Renal Function Preservation in Peritoneal Dialysis Patients

The survival advantage observed among peritoneal dialysis patients early on after dialysis initiation has been largely attributed to residual renal function (RRF) preservation due to higher baseline residual function and fewer comorbidities. We hypothesize that a rapid decline in RRF is associated with higher risk of anuria and mortality. In a retrospective cohort study of 581 subjects on peritoneal dialysis with longitudinal prevalent data, we assessed whether RRF change over time, in addition to baseline RRF, increased risk of mortality and anuria using Kaplan-Meier analysis and Cox proportional hazard analysis to control for known risk factors. Rapid RRF decline (≥ 0.09 decline) over a 12-month period was associated with a 2.6-fold increase in the risk of death (hazard ratio [HR] 2.60, 95% confidence interval [CI] 1.66 - 4.07, compared with < 0.09 decline) and a 2-fold increase in anuria (HR 2.06, 95% CI 1.24 - 3.42). Each quartile of increasing severity of RRF decline over a 12-month period increased risk incrementally for death (2^nd quartile: HR 3.04, CI 1.26 - 7.34; 3^rd quartile: HR 4.01, CI 1.71 - 9.83; 4^th quartile HR 5.78, CI 2.10 - 15.9) and generally for anuria (quartiles with HR 5.72 - 7.21). The escalating risk of mortality and anuria was greater for those with diabetes mellitus. In conclusion, rapid decline in RRF over a 12-month period increased the risk of mortality and likewise anuria, beyond previously established risk factors for mortality and anuria. The impact on mortality and RRF preservation was particularly severe for those with diabetes mellitus.

Factors associated with residual urine volume preservation in patients undergoing hemodialysis for end-stage kidney disease in Kinshasa

BACKGROUND

Decreased residual urine volume (RUV) is associated with higher mortality in hemodialysis (HD). However, few studies have examined RUV in patients on HD in Sub-Saharan Africa. The aim of this study was to identify predictors of RUV among incident hemodialysis patients in Kinshasa.

METHODS

This historical cohort study enrolled 250 patients with ESRD undergoing hemodialysis between January 2007 and July 2013 in two hemodialysis centers in Kinshasa. RUV were collected over 24 h at the initiation of HD and 6 and 12 months later during the interdialytic period. We compared the baseline characteristics of the patients according to their initial RUV (≤ 500 ml/day vs >  500 ml/day) using Student's t, Mann-Whitney U and Chi2 tests. Linear mixed-effects models were used to search for predictors of decreased RUV by adding potentially predictive baseline covariates of the evolution of RUV to the effect of time: age, sex, diabetes mellitus, hypertension, diastolic blood pressure, diuretics, angiotensin conversion enzyme inhibitors (ACEI), angiotensin receptor blockers, hypovolemia, chronic tubulointerstitial nephropathy, left ventricular hypertrophy and initial hemodialysis characteristic. A value of p < 0.05 was considered the threshold of statistical significance.

RESULTS

The majority of hemodialysis patients were male (68.8%, sex ratio 2.2), with a mean age of 52.5 ± 12.3 years. The population's RUV decreased with time, but with a slight deceleration. The mean RUV values were 680 ± 537 ml/day, 558 ± 442 ml/day and 499 ± 475 ml/day, respectively, at the initiation of HD and at 6 and 12 months later. The use of ACEI at the initiation of HD (beta coefficient 219.5, p < 0.001) and the presence of chronic tubulointerstitial nephropathy (beta coefficient 291.8, p = 0.007) were significantly associated with RUV preservation over time. In contrast, the presence of left ventricular hypertrophy at the initiation of HD was significantly associated with decreased RUV over time (beta coefficient - 133.9, p = 0.029).

CONCLUSIONS

Among incident hemodialysis patients, the use of ACEI, the presence of chronic tubulointerstitial nephropathy and reduced left ventricular hypertrophy are associated with greater RUV preservation in the first year of dialysis.

Baseline and Time-Averaged Values Predicting Residual Renal Function Decline Rate in Japanese Peritoneal Dialysis Patients

Residual renal function (RRF) is a strong prognostic factor of morbidity and mortality in patients undergoing peritoneal dialysis (PD). We determined predictors of the RRF rate of decline using both baseline values and time-averaged ones. We retrospectively analyzed 94 patients being treated with PD at the Japanese Red Cross Medical Center. The decline rate of RRF was calculated by a diminution in the weekly renal Kt/V between the first and last follow up divided by follow-up years. The mean follow-up period was 2.28 years, and the mean decline rate of weekly renal Kt/V was 0.25 per year. A multivariate analysis using baseline parameters identified dialysis-to-plasma ratios of creatinine at 4 h (P = 0.02), urinary protein (P = 0.02), and mean blood pressure (MBP) (P < 0.01) as being positively associated with the RRF rate of decline, while the use of angiotensin converting enzyme inhibitor (ACEI)/angiotensin receptor blocker (ARB) had a negative correlation (P = 0.03). When using time-averaged values as independent variables, a lower weekly total renal Kt/V (P < 0.0001), higher urinary protein (P < 0.0001), and higher MBP (P = 0.04) independently predicted a faster RRF rate of decline. We demonstrated that PD patients with a lower MBP and lower urinary protein both at baseline and throughout their PD duration had a slower RRF rate of decline. We recommend strict control of blood pressure and anti-proteinuric therapy for PD patients.

Renin-angiotensin system blockers and residual kidney function loss in patients initiating peritoneal dialysis: an observational cohort study

Background

Although angiotensin-converting enzyme inhibitors (ACEI) and angiotensin-II receptor blockers (ARB) have been shown to preserve residual kidney function in a select group of Asian patients undergoing continuous ambulatory peritoneal dialysis (PD) in two small randomized clinical trials, the effectiveness of these drugs has yet to be demonstrated in a more diverse population of patients with multiple comorbid conditions. We investigated the association between ACEI/ARB use and development of recorded anuria in a cohort of patients initiating PD in the U.S.

Methods

We conducted a retrospective observational cohort study using the US Renal Data System and electronic health records data from a large national dialysis provider. We identified adult patients who initiated PD from 2007 to 2011. Only patients who participated in the federal prescription drug benefit program, Medicare Part D, for the first 90 days of dialysis were included. Patients who filled a prescription for an ACEI or ARB during those 90 days were considered users. We applied Cox proportional hazards models to an inverse probability of treatment-weighted (IPTW) cohort to estimate the hazard ratio (HR) for anuria (24-h urine volume < 200 ml) in ACEI/ARB users vs. non-users.

Results

Among 886 patients, 389 (44%) used an ACEI/ARB. Almost a third of these patients were black or Hispanic, and more than a quarter had comorbidities that would have excluded them from the randomized clinical trials of ACEI/ARB. Two hundred eighty patients reached anuria over 840 person-years of follow-up, for a composite event rate of 33 events per 100 person-years. We found no clear association between ACEI/ARB use and progression to anuria [HR: 0.86, 95% CI: 0.73–1.02].

Conclusions

ACEI/ARB use is common in patients initiating PD in the U.S. but was not associated with a lower risk of anuria. Residual confounding by unmeasured variables is an important limitation of this observational study. Still, these findings suggest that pragmatic clinical trials are warranted to test the effectiveness of ACEI/ARB in slowing the decline of residual kidney function in a diverse population of peritoneal dialysis patients with multiple comorbid conditions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0616-4) contains supplementary material, which is available to authorized users.

Predictors of Residual Renal Function Decline in Peritoneal Dialysis Patients: The balANZ Trial

Objective

Preservation of residual renal function (RRF) is associated with improved survival. The aim of the present study was to identify independent predictors of RRF and urine volume (UV) in incident peritoneal dialysis (PD) patients.

Methods

The study included incident PD patients who were balANZ trial participants. The primary and secondary outcomes were RRF and UV, respectively. Both outcomes were analyzed using mixed effects linear regression with demographic data in the first model and PD-related parameters included in a second model.

Results

The study included 161 patients (mean age 57.9 ± 14.1 years, 44% female, 33% diabetic, mean follow-up 19.5 ± 6.6 months). Residual renal function declined from 7.5 ± 2.9 mL/min/1.73 m2 at baseline to 3.3 ± 2.8 mL/min/1.73 m2 at 24 months. Better preservation of RRF was independently predicted by male gender, higher baseline RRF, higher time-varying systolic blood pressure (SBP), biocompatible (neutral pH, low glucose degradation product) PD solution, lower peritoneal ultrafiltration (UF) and lower dialysate glucose exposure. In particular, biocompatible solution resulted in 27% better RRF preservation. Each 1 L/day increase in UF was associated with 8% worse RRF preservation ( p = 0.007) and each 10 g/day increase in dialysate glucose exposure was associated with 4% worse RRF preservation ( p < 0.001). Residual renal function was not independently predicted by body mass index, diabetes mellitus, renin angiotensin system inhibitors, peritoneal solute transport rate, or PD modality. Similar results were observed for UV.

Conclusions

Common modifiable risk factors which were consistently associated with preserved RRF and residual UV were use of biocompatible PD solutions and achievement of higher SBP, lower peritoneal UF, and lower dialysate glucose exposure over time.

Risk Factors for Decline of Residual Renal Function in Children Treated With Peritoneal Dialysis

♦ BACKGROUND: The aim of the study was to assess risk factors for residual renal function (RRF) decline in children during the first/second year of chronic peritoneal dialysis (PD). ♦ METHODS: The study group included 56 children with end-stage renal disease (ESRD) (age 10.13 ± 4.86 years), including 18 on continuous ambulatory PD (CAPD) and 38 on automated PD (APD), in whom we evaluated RRF (daily diuresis [mL/m2/24 h], residual glomerular filtration rate (rGFR) [mL/min/1.73 m2]), etiology of ESRD, PD fluid volume (mL/m2/24 h), glucose load (g/m2/24 h), ultrafiltration (mL/m2/24 h), peritoneal permeability (D/PCrea 4h, D/D0 Glu 4h), dialysis adequacy (twKt/V, twCCr [L/week/1.73 m2]), blood pressure (BP), biochemical parameters, and medications used. Duration of follow-up was 24 months. ♦ RESULTS: Mean diuresis before initiation of PD was 1,394.93 ± 698.37 (mL/m2/24 h), and mean rGFR was 7.41 ± 3.96 (mL/min/1.73 m2). The rate of daily diuresis decline was -529.34 ± 546.28 in the first year and -107.10 ± 291.54 (mL/m2/24 h) in the second year (p = 0.005), and the rate of rGFR decline was -3.35 ± 3.73 in the first year and -1.63 ± 1.85 (mL/min/1.73 m2) in the second year (p = 0.118). Eleven (19.64%) patients became anuric. In univariate analysis, the rate of daily diuresis decline in the first year was related to baseline diuresis (r = -0.29, p = 0.031), proteinuria (r = -0.43, p = 0.001), and systolic BP (r = -0.31, p = 0.020); 12-month changes (Δ0 - 12) in PD fluid volume (r = -0.37, p = 0.004), glucose load (r = -0.28, p = 0.035), and ultrafiltration (r = -0.38, p = 0.004); serum calcium-phosphorus product (r = -0.41, p = 0.002); and Δ0 - 12 body mass index (BMI) Z-score (r = 0.30, p = 0.024); while the rate of rGFR decline in the first year was related only to baseline rGFR (r = -0.57, p < 0.001). In multivariate analysis, significant predictors of the rate of daily diuresis decline in the first year were baseline diuresis (β = -0.386, p < 0.001) and proteinuria (β = -0.278, p = 0.017), mean systolic BP Z-score (β = -0.237, p = 0.027), and age at the onset of PD (β = -0.224, p = 0.037), while predictors of the rate of rGFR decline were baseline rGFR (β = -0.607, p < 0.001) and baseline proteinuria (β = -0.225, p = 0.046). In the second year, the only predictors of the rate of rGFR decline were D/D0 Glu 4h (r = 0.44, p = 0.033, univariate analysis) and rGFR at 12 months (β = -0.499, p = 0.044). ♦ CONCLUSION: The most important risk factors for rapid RRF decline in children during the first year of chronic PD include higher baseline daily diuresis and proteinuria, and additional factors are systolic BP and age at the onset of PD; while high baseline GFR and low peritoneal transport status may be the only important factors during the second year.

Protective effect of mycophenolate mofetil on residual renal function in peritoneal dialysis patients: An open label feasibility study

AIM

This study aims to evaluate the safety of mycophenolate mofetil (MMF) and its effect on residual renal function (RRF) during peritoneal dialysis (PD).

METHODS

This is a prospective, randomized study comprising 60 PD patients. The patients were assigned either to the MMF group (MMF dosage: 1.0-1.5 g/day in two divided doses for 6 months, followed by a dose of 0.5-0.75 g/day for another 6 months) or to the control group. The patients close monitoring for 1 year. Variables related to residual renal function, including urine volume, measured glomerular filtration rate (GFR), and renal Kt/V, were measured at four time points.

RESULTS

There were no significant changes in urinary protein excretion in either group (P > 0.05). The MMF group showed a significantly higher urine volume than the control group (955.38 ± 243.54 vs 786.15 ± 279.62 mL/day, P = 0.024). The renal kt/V was also significantly higher in the MMF group (0.59 ± 0.11 in MMF vs 0.50 ± 0.19 in control group, P = 0.032). There was significant difference in the renal measured GFR between the two groups at 6, 9 and 12 months (MMF vs control at 6 months, 6.14 ± 0.66 vs 5.58 ± 0.65 mL/min per 1.73m² , P = 0.003; at 9 months, 5.68 ± 0.80 vs 4.78 ± 0.75, P < 0.001; at 12 months, 5.44 ± 0.91 vs 4.43 ± 0.93, P < 0.001). MMF was well tolerated without any serious complications.

CONCLUSION

The use of MMF in PD patients tends to better preserve RRF.

Preservation of residual kidney function in hemodialysis patients: reviving an old concept

Residual kidney function (RKF) may confer a variety of benefits to patients on maintenance dialysis. RKF provides continuous clearance of middle molecules and protein-bound solutes. Whereas the definition of RKF varies across studies, interdialytic urine volume may emerge as a pragmatic alternative to more cumbersome calculations. RKF preservation is associated with better patient outcomes including survival and quality of life and is a clinical parameter and research focus in peritoneal dialysis. We propose the following practical considerations to preserve RKF, especially in newly transitioned (incident) hemodialysis patients: (1) periodic monitoring of RKF in hemodialysis patients through urine volume and including residual urea clearance with dialysis adequacy and outcome markers such as anemia, fluid gains, minerals and electrolytes, nutritional, status and quality of life; (2) avoidance of nephrotoxic agents such as radiocontrast dye, nonsteroidal anti-inflammatory drugs, and aminoglycosides; (3) more rigorous hypertension control and minimizing intradialytic hypotensive episodes; (4) individualizing the initial dialysis prescription with consideration of an incremental/infrequent approach to hemodialysis initiation (e.g., twice weekly) or peritoneal dialysis; and (5) considering a lower protein diet, especially on nondialysis days. Because RKF appears to be associated with better patient outcomes, it requires more clinical and research focus in the care of hemodialysis and peritoneal dialysis patients.

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 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

♦

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.

Strategies for preserving residual renal function in peritoneal dialysis patients

Although there have been many advancements in the treatment of patients with chronic kidney disease (CKD) over the last 50 years, in terms of reducing cardiovascular risk, mortality remains unacceptably high, particularly for those patients who progress to stage 5 CKD and initiate dialysis (CKD5d). As mortality risk increases exponentially with progressive CKD stage, the question arises as to whether preservation of residual renal function once dialysis has been initiated can reduce mortality risk. Observational studies to date have reported an association between even small amounts of residual renal function and improved patient survival and quality of life. Dialysis therapies predominantly provide clearance for small water-soluble solutes, volume and acid-base control, but cannot reproduce the metabolic functions of the kidney. As such, protein-bound solutes, advanced glycosylation end-products, middle molecules and other azotaemic toxins accumulate over time in the anuric CKD5d patient. Apart from avoiding potential nephrotoxic insults, observational and interventional trials have suggested that a number of interventions and treatments may potentially reduce the progression of earlier stages of CKD, including targeted blood pressure control, reducing proteinuria and dietary intervention using combinations of protein restriction with keto acid supplementation. However, many interventions which have been proven to be effective in the general population have not been equally effective in the CKD5d patient, and so the question arises as to whether these treatment options are equally applicable to CKD5d patients. As strategies to help preserve residual renal function in CKD5d patients are not well established, we have reviewed the evidence for preserving or losing residual renal function in peritoneal dialysis patients, as urine collections are routinely collected, whereas few centres regularly collect urine from haemodialysis patients, and haemodialysis dialysis patients are at risk of sudden intravascular volume shifts associated with dialysis treatments. On the other hand, peritoneal dialysis patients are exposed to a variety of hypertonic dialysates and episodes of peritonitis. Whereas blood pressure control, using an angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB), and low-protein diets along with keto acid supplementation have been shown to reduce the rate of progression in patients with earlier stages of CKD, the strategies to preserve residual renal function (RRF) in dialysis patients are not well established. For peritoneal dialysis patients, there are additional technical factors that might aggravate the rate of loss of residual renal function including peritoneal dialysis prescriptions and modality, bio-incompatible dialysis fluid and over ultrafiltration of fluid causing dehydration. In this review, we aim to evaluate the evidence of interventions and treatments, which may sustain residual renal function in peritoneal dialysis patients.

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.

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.

Effect of body mass index on outcomes of peritoneal dialysis patients in India

OBJECTIVES

We studied the effect of body mass index (BMI) at peritoneal dialysis (PD) initiation on patient and technique survival and on peritonitis during follow-up.

METHODS

We followed 328 incident patients on PD (176 with diabetes; 242 men; mean age: 52.6 ± 12.6 years; mean BMI: 21.9 ± 3.8 kg/m(2)) for 20.0 ± 14.3 months. Patients were categorized into four BMI groups: obese, ≥ 25 kg/m(2); overweight, 23 - 24.9 kg/m(2); normal, 18.5 - 22.9 kg/m(2) (reference category); and underweight, <18.5 kg/m(2). The outcomes of interest were compared between the groups.

RESULTS

Of the 328 patients, 47 (14.3%) were underweight, 171 (52.1%) were normal weight, 53 (16.2%) were overweight, and 57 (17.4%) were obese at commencement of PD therapy. The crude hazard ratio (HR) for mortality (p = 0.004) and the HR adjusted for age, subjective global assessment, comorbidities, albumin, diabetes, and residual glomerular filtration rate (p = 0.02) were both significantly greater in the underweight group than in the normal-weight group. In comparison with the reference category, the HR for mortality was significantly greater for underweight PD patients with diabetes [2.7; 95% confidence interval (CI): 1.5 to 5.0; p = 0.002], but similar for all BMI categories of nondiabetic PD patients. Median patient survival was statistically inferior in underweight patients than in patients having a normal BMI. Median patient survival in underweight, normal, overweight, and obese patients was, respectively, 26 patient-months (95% CI: 20.9 to 31.0 patient-months), 50 patient-months (95% CI: 33.6 to 66.4 patient-months), 57.7 patient-months (95% CI: 33.2 to 82.2 patient-months), and 49 patient-months (95% CI: 18.4 to 79.6 patient-months; p = 0.015). Death-censored technique survival was statistically similar in all BMI categories. In comparison with the reference category, the odds ratio for peritonitis occurrence was 1.8 (95% CI: 0.9 to 3.4; p = 0.086) for underweight patients; 1.7 (95% CI: 0.9 to 3.2; p = 0.091) for overweight patients; and 3.4 (95% CI: 1.8 to 6.4; p < 0.001) for obese patients.

CONCLUSIONS

In our PD patients, mean BMI was within the normal range. The HR for mortality was significantly greater for underweight diabetic PD patients than for patients in the reference category. Death-censored technique survival was similar in all BMI categories. Obese patients had a greater risk of peritonitis.