The Role of Kt/V and Creatinine Clearance on Assisting Optimization of Serum Phosphorus Levels among Patients on Peritoneal Dialysis

Key Points

This is a retrospective observational multinational peritoneal dialysis study to test whether creatinine clearance could be a better marker of serum phosphorus than urea Kt/V. Creatinine clearance was not more accurate predicting serum phosphorus than urea Kt/V, but its inclusion in multivariable models added more clarity. In conclusion, using both biomarkers, instead of just one, may better assist in the optimization of serum phosphorus levels.

Background

Hyperphosphatemia is associated with poor outcome and is still very common in peritoneal dialysis (PD) patients. Because peritoneal phosphorus clearance is closer to peritoneal creatinine clearance (CrCl) than urea clearance, we hypothesized that weekly CrCl could be a better marker of serum phosphorus in PD.

Methods

In a retrospective observational study, data from adult PD patients were collected across five institutions in North and South America: Fresenius Medical Care Latin America, Renal Research Institute, Mount Sinai Hospital, Hospital Civil de Guadalajara, and the Brazil PD cohort. All centers analyzed routinely available laboratory data, with exclusions for missing data on serum phosphorus, CrCl, or urea Kt/V. A unified statistical protocol was used across centers. Linear mixed-effect models examined associations between longitudinal serum phosphorus levels, CrCl, and Kt/V. Adjustments were made for age, sex, and baseline phosphorus binder usage. Mixed-effects meta-analysis determined the pooled effect size of CrCl and Kt/V on serum phosphorus trajectories, adjusted for confounders.

Results

There were 16,796 incident PD patients analyzed. Age, body mass index, sex, PD modality, Kt/V, and CrCl, as well as serum phosphorus, varied significantly across the different cohorts, but >70% had residual renal function. For most cohorts, both CrCl total and urea Kt/V associated negatively with serum phosphorus levels, and log-likelihood ratio tests demonstrate that models including CrCltotal have more predictive information than those including only urea Kt/V for the largest cohorts. Models including CrCltotal increase information predicting longitudinal serum phosphorus levels irrespective of baseline urea Kt/V, age, use of phosphorus binder, and sex.

Conclusions

CrCl was not more accurate in predicting serum phosphorus than urea Kt/V, but its inclusion in multivariable models predicting serum phosphorus added accuracy. In conclusion, both CrCl and Kt/V are associated with phosphorus levels, and using both biomarkers, instead of just one, may better assist in the optimization of serum phosphorus levels.

Rationale and design of ELIXIR, a randomized, controlled trial to evaluate efficacy and safety of XyloCore, a glucose-sparing solution for peritoneal dialysis

Peritoneal dialysis adoption and technique survival is affected by limitations related to peritoneal membrane longevity and metabolic alterations. Indeed, almost all peritoneal dialysis fluids exploit glucose as an osmotic agent that rapidly diffuses across the peritoneal membrane, potentially resulting in metabolic abnormalities such as hyperglycemia, hyperinsulinemia, obesity, and hyperlipidemia. Moreover, glucose-degradation products generated during heat sterilization, other than glucose itself, induce significant morphological and functional changes in the peritoneum leading to ultrafiltration failure. The partial substitution of glucose with osmotic agents characterized by a better local and systemic biocompatibility has been suggested as a potential strategy to innovate peritoneal dialysis fluids. The approach aims to minimize glucose-associated toxicity, preserving the peritoneal membrane welfare and counteracting common comorbidities. In this work, we report the clinical trial design of ELIXIR, a phase III randomized, controlled, blinded outcome assessment study comparing Xylocore®, an innovative formulation based on Xylitol and l-carnitine, to standard glucose-based regimens, in end-stage kidney disease patients treated with continuous ambulatory peritoneal dialysis; 170 patients will be randomized (1:1) to receive XyloCore® or to continue their pre-randomization peritoneal dialysis (PD) therapy with glucose-only PD solutions, for 6 months. The primary study's objective is to demonstrate the noninferiority of XyloCore® in terms of Kt/V urea, for which a clinically acceptable noninferiority margin of -0.25 has been determined, assuming that all patients will be treated aiming to a minimum target of 1.7 and an optimal target of 2.0.

Comparison of the Watson formula and bioimpedance spectroscopy for measuring body volume and calculating kt/V in patients with peritoneal dialysis

CONCLUSION

There were significant differences between Vwat and Vbis and between Kt/Vwat and Kt/Vbis. Kt/Vwat may underestimate small-solute dialysis adequacy in most cases. Kt/Vbis instead of Kt/Vwat could be accounted for in creating individualized dialysis prescriptions if the patient has no obvious clinical symptoms.

Structures for quality assurance and measurements for kidney replacement therapies: A multinational study from the ISN-GKHA

AIM

Optimal care for patients with kidney failure reduces the risks of adverse health outcomes, including cardiovascular events and death. We evaluated data from the third iteration of the International Society of Nephrology Global Kidney Health Atlas (ISN-GKHA) to assess the capacity for quality service delivery for kidney failure care across countries and regions.

METHOD

We explored the quality of kidney failure care delivery and the monitoring of quality indicators from data provided by an international survey of stakeholders from countries affiliated with the ISN from July to September 2022.

RESULTS

One hundred and sixty seven countries participated in the survey, representing about 97.4% of the world's population. In countries where haemodialysis (HD) was available, 81% (n = 134) provided standard HD sessions (three times weekly for 3-4 h per session) to patients. Among countries with peritoneal dialysis (PD) services, 61% (n = 101) were able to provide standard PD care (3-4 exchanges per day). In high-income countries, 98% (n = 62) reported that >75% of centers regularly monitored dialysis water quality for bacteria compared to 28% (n = 5) of low-income countries (LICs). Capacity to monitor the administration of immunosuppression drugs was generally available in 21% (n = 4) of LICs, compared to 90% (n = 57) of high-income countries. There was significant variability between and within regions and country income groups in reporting the quality of services utilized for kidney replacement therapies.

CONCLUSION

Quality assurance standards on diagnostic and treatment tools were variable and particularly infrequent in LICs. Standardization of delivered care is essential for improving outcomes for people with kidney failure.

Clinical guideline on adequacy and prescription of peritoneal dialysis

In recent years, the meaning of adequacy in peritoneal dialysis has changed. We have witnessed a transition from an exclusive achievement of specific objectives -namely solute clearances and ultrafiltration- to a more holistic approach more focused to on the quality of life of these patients. The purpose of this document is to provide recommendations, updated and oriented to social and health environment, for the adequacy and prescription of peritoneal dialysis. The document has been divided into three main sections: adequacy, residual kidney function and prescription of continuous ambulatory peritoneal dialysis and automated peritoneal dialysis. Recently, a guide on the same topic has been published by a Committee of Experts of the International Society of Peritoneal Dialysis (ISPD 2020). In consideration of the contributions of the group of experts and the quasi-simultaneity of the two projects, references are made to this guide in the relevant sections. We have used a systematic methodology (GRADE), which specifies the level of evidence and the strength of the proposed suggestions and recommendations, facilitating future updates of the document.

Peritoneal Phosphate Clearance: Determinants and Association With Mortality

BACKGROUND

Dialytic phosphate removal is a cornerstone of the management of hyperphosphatemia in peritoneal dialysis (PD) patients, but the influencing factors on peritoneal phosphate clearance (PPC) are incompletely understood. Our objective was to explore clinically relevant factors associated with PPC in patients with different PD modality and peritoneal transport status and the association of PPC with mortality.

METHODS

This is a cross-sectional and prospective observational study. Four hundred eighty-five PD patients were enrolled and divided into 2 groups according to PPC. All-cause mortality was evaluated after followed-up for at least 3 months.

RESULTS

High PPC group showed lower mortality compared with Low PPC group by Kaplan-Meier analysis and log-rank test. Both multivariate linear regression and multivariate logistic regression revealed that high transport status, total effluent dialysate volume per day, continuous ambulatory PD (CAPD), and protein in total effluent dialysate volume appeared to be positively correlated with PPC; body mass index (BMI) and the normalized protein equivalent of total nitrogen appearance (nPNA) were negatively correlated with PPC. Besides PD modality and membrane transport status, total effluent dialysate volume showed a strong relationship with PPC, but the correlation differed among PD modalities.

CONCLUSIONS

Higher PPC was associated with lower all-cause mortality risk in PD patients. Higher PPC correlated with CAPD modality, fast transport status, higher effluent dialysate volume and protein content, and with lower BMI and nPNA.

Delivering Person-Centered Peritoneal Dialysis

Peritoneal dialysis (PD) enables people to have a home-based therapy, permitting greater autonomy for individuals along with enhanced treatment satisfaction compared with in-center dialysis care. The burden of treatment on PD, however, remains considerable and underpins the need for person-centered care. This reflects the need to address the patient as a person with needs and preferences beyond just the medical perspective. Shared decision making is central to the recent International Society for Peritoneal Dialysis recommendations for prescribing PD, balancing the potential benefits of PD on patient well-being with the burden associated with treatment. This review considers the role of high-quality goal-directed prescribing, incremental dialysis, and remote patient monitoring in reducing the burden of dialysis, including an approach to implementing incremental PD. Although patient-related outcomes are important in assessing the response to treatment and, particularly life participation, the corollary of dialysis burden, there are no clear routes to the clinical implementation of patient-related outcome measures. Delivering person-centered care is dependent on treating people both as individuals and as equal partners in their care.

Correlation of Serum Asprosin Levels With Normalized Protein Catabolic Rate in Patients Receiving Peritoneal Dialysis Treatment

Background Peritoneal dialysis patients are malnourished due to loss of protein in the dialysate and inadequate dialysis, although they take additional calories every day during treatment. Many parameters are used to assess nutritional status, with normalized protein catabolic rate (nPCR) being one of the most common. Asprosin, a novel adipokine secreted by adipose tissue, peaks during fasting and induces hepatic glucose release through the activation of the G-protein-cAMP-PKA pathway, which has been indicated to have a curative effect on chronic inflammation. In this study, we aimed to investigate the relationship between asprosin levels and nutritional parameters in patients receiving peritoneal dialysis treatment as well as to investigate the applicability of more practical tests. Methodology A total of 70 peritoneal dialysis patients, 35 female (59%) and 24 male (41%), were included in the study. The mean age of the patients was 53 ± 14 years (range = 18-80 years), and the median peritoneal dialysis duration was 31.5 months (range = 20-56.2 months). The most common etiologic cause was hypertension (37%). Patients over 18 years of age who had been receiving peritoneal dialysis treatment for at least 24 months were included in the study. The correlation between patients' nPCR levels and serum asprosin, body mass index, and lipids was evaluated. Results The correlation between the level of nPCR and the serum asprosin level, body mass index, and lipids was evaluated. Patients with nPCR <0.815 were considered malnourished, and factors affecting malnutrition were determined by univariate analysis. Among the factors affecting malnutrition according to univariate analysis, those with p-value <0.05 were analyzed by multivariate analysis. Low asprosin level was one of the independent factors affecting malnutrition in patients (Exp(B) = 0.944, 95% confidence interval (CI) = 0.896-0.994). Other independent factors affecting malnutrition were Kt/V (Exp(B) = 0.018, 95% CI = 0.001-0.550) and residual renal function (Exp(B) = -0.004, 95% CI = 0.993-0.999). Conclusions There is a need for more accessible tests and reliable parameters to evaluate dialysis and nutritional deficiency in peritoneal dialysis patients. One possible hormone that could serve as a guide is asprosin.

Literature review: Combined therapy with peritoneal dialysis and hemodialysis as renal replacement therapy

Background

Peritoneal dialysis (PD) is the recommended renal replacement therapy for patients with end-stage kidney disease. Complementary hemodialysis (HD) once per week for PD patients can aid in achieving adequate dialysis and extend the duration of PD treatment. In Japan, this therapy is termed “combined therapy with PD and hemodialysis (combPDHD).” CombPDHD represents a treatment option for PD patients for whom adequate dialysis cannot be maintained. CombPDHD has been widely applied in Japanese PD patients; however, it is much less common outside of Japan. Clinical evidence, particularly regarding long-term prognosis and appropriate duration of treatment, remains insufficient.

Summary

CombPDHD will be required as an alternative for increasing the dose of PD under various conditions, such as a loss of residual kidney function (RKF) and peritoneal functional failure. The Japanese regimen for combPDHD involves 5 or 6 days of PD, combined with one weekly session of hemodialysis. According to some reports, the potential benefits of combPDHD are peritoneal rest with improved peritoneal function and delay in membrane deterioration. CombPDHD prevents peritoneal dysfunction and reduces cardiovascular complications by adjusting the fluid volume and improving renal anemia. Increased D/PCr indicates a deterioration in peritoneal function and is an independent risk factor for encapsulating peritoneal sclerosis (EPS). It is previously reported that no significant differences in combPDHD duration were observed between EPS and non-EPS groups. Laparoscopic findings involving patients with combPDHD revealed that there was a difference in abdominal wall degeneration depending on the intra-abdominal cavity of each case. Recently, prospective studies on long-term peritoneal function, survival, and hospitalization in combPDHD have been reported. However, reviews evaluating combPDHD long-term outcomes in multicenter and prospective studies are lacking.

Conclusion

It is difficult to continue PD alone with a declining RKF or when self-management is poor. Hence, combPDHD should be started to adjust the fluid volume, with adequate dialysis dose and peritoneal rest. This therapy is useful from a lifestyle viewpoint during the transition period from PD to HD and should not be continued indefinitely.

Clinical Factors Associated with Serum Magnesium Concentration in Patients Undergoing Peritoneal Dialysis: A Single-Center Observational Study

Purpose

Magnesium (Mg) is an essential element that is associated with various physiological functions, such as maintenance of blood pressure, muscle contraction, and nerve function. In patients undergoing hemodialysis, hypomagnesemia is associated with cardiovascular and all-cause mortality. However, in patients undergoing peritoneal dialysis (PD), clinical factors associated with Mg have not been fully investigated.

Patients and Methods

Clinical factors including anthropometric data, comorbidities, laboratory data, medications, and dialysis methods were collected from the medical records of patients undergoing PD. The associations of these factors with the serum Mg concentration were investigated by univariate and multivariate analyses.

Results

Sixty patients undergoing PD were investigated. The univariate analysis showed that the serum Mg concentration was significantly associated with treatment by hybrid PD (daily PD + once-weekly hemodialysis) (β = 0.264, P = 0.04), administration of phosphate binders (β = 0.294, P = 0.02), the serum C-reactive protein concentration (β = -0.318, P = 0.01), the serum potassium (K) concentration (β = 0.451, P < 0.01), and the serum intact parathormone concentration (β = -0.333, P = 0.01). The multivariate analysis using these factors showed an independent association between the serum Mg and K concentrations (β = 0.333, P = 0.01).

Conclusion

The serum Mg concentration was independently associated with the serum K concentration in patients undergoing PD.

Variation in Peritoneal Dialysis Time on Therapy by Country: Results from the Peritoneal Dialysis Outcomes and Practice Patterns Study

BACKGROUND AND OBJECTIVES

Quantifying contemporary peritoneal dialysis time on therapy is important for patients and providers. We describe time on peritoneal dialysis in the context of outcomes of hemodialysis transfer, death, and kidney transplantation on the basis of the multinational, observational Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) from 2014 to 2017.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Among 218 randomly selected peritoneal dialysis facilities (7121 patients) in the PDOPPS from Australia/New Zealand, Canada, Japan, Thailand, the United Kingdom, and the United States, we calculated the cumulative incidence from peritoneal dialysis start to hemodialysis transfer, death, or kidney transplantation over 5 years and adjusted hazard ratios for patient and facility factors associated with death and hemodialysis transfer.

RESULTS

Median time on peritoneal dialysis ranged from 1.7 (interquartile range, 0.8-2.9; the United Kingdom) to 3.2 (interquartile range, 1.5-6.0; Japan) years and was longer with lower kidney transplantation rates (range: 32% [the United Kingdom] to 2% [Japan and Thailand] over 3 years). Adjusted hemodialysis transfer risk was lowest in Thailand, but death risk was higher in Thailand and the United States compared with most countries. Infection was the leading cause of hemodialysis transfer, with higher hemodialysis transfer risks seen in patients having psychiatric disorder history or elevated body mass index. The proportion of patients with total weekly Kt/V ≥1.7 at a facility was not associated with death or hemodialysis transfer.

CONCLUSIONS

Countries in the PDOPPS with higher rates of kidney transplantation tended to have shorter median times on peritoneal dialysis. Identification of infection as a leading cause of hemodialysis transfer and patient and facility factors associated with the risk of hemodialysis transfer can facilitate interventions to reduce these events.

PODCAST

This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_05_31_CJN16341221.mp3.

Association of serum potassium with decline in residual kidney function in incident hemodialysis patients

BACKGROUND

Hyperkalemia is associated with kidney function decline in patients with non-dialysis dependent chronic kidney disease, but this relationship is unclear for residual kidney function among hemodialysis (HD) patients.

METHODS

We conducted a retrospective cohort study of 6655 patients who started HD from January 2007 to December 2011 and who had data on renal urea clearance (KRU). Serum potassium levels were stratified into four groups (i.e. ≤4.0, >4.0 to ≤ 4.5, >4.5 to ≤ 5.0, >5.0 mEq/L) and 1-year KRU slope for each group was estimated by a linear mixed-effects model.

RESULTS

Higher serum potassium was associated with greater decline in KRU, and the greatest decrease in KRU (-0.20, 95% CI -0.50, -0.06) was observed for baseline potassium > 5.0 mEq/L in the fully adjusted model. Mediation analysis showed that KRU slope mediated 1.78% of the association between serum potassium and mortality.

CONCLUSIONS

In conclusion, hyperkalemia is associated with decline in residual kidney function amongst incident HD patients. These findings may have important clinical implications in the management of hyperkalemia in advanced CKD if confirmed in additional studies including clinical trials.

Association between serum β2-microglobulin and mortality in Japanese peritoneal dialysis patients: A cohort study

Background

Higher serum β2-microglobulin (B2M) concentrations are associated with higher mortality in the general population, non-dialyzed chronic kidney disease patients and patients receiving hemodialysis (HD). However, this relationship among patients on peritoneal dialysis (PD) has not been validated.

Methods

We collected baseline data for 3,011 prevalent PD patients from a nationwide dialysis registry in Japan at the end of 2010. Clinical outcomes for 9 years were then evaluated using the registry at the end of 2011 to 2019. All-cause and cardiovascular (CV) mortality was assessed using Cox regression analysis and competing-risks regression analysis, respectively. We used multiple imputation to deal with missing covariate data.

Results

During a median follow-up of 87 months, 2,054 patients transferred to combined therapy with PD and HD or HD directly. A total of 3,011 patients, 1,235 (41.0%) died, including 437 patients (14.5%) from CV causes. Among them, 612 patients died after transfer to other dialysis modalities. Univariate analyses revealed no significant association between serum B2M and mortality, whereas higher serum B2M was independently associated with both all-cause and CV mortalities in adjusted models. However, the significant association between serum B2M and CV mortality disappeared in analysis treating serum B2M as a categorical variable. The effect of serum B2M on all-cause mortality was significantly higher among patients with higher urinary volume and a significant interaction was evident.

Conclusions

Using a large-scale registry, we found that serum B2M contributes tenuously but significantly to worse outcome and residual kidney function significantly affects this relationship. On the contrary, serum B2M per se had no predictive value for patient outcome in prevalent PD patients.

Osteoprotegerin Is a Better Predictor for Cardiovascular and All-Cause Mortality than Vascular Calcifications in a Multicenter Cohort of Patients on Peritoneal Dialysis

The purpose of this study was to compare vascular calcification (VC), serum osteoprotegerin (OPG) levels, and other biochemical markers to determine their value as available predictors of all-cause and cardiovascular (CV) mortality in patients on peritoneal dialysis (PD). A total of 197 patients were recruited from seven dialysis centers in Mexico City. VC was assessed with multi-slice computed tomography, measured using the calcification score (CaSc). OPG, albumin, calcium, hsC-reactive protein, phosphorous, osteocalcin, total alkaline phosphatase, and intact parathormone were also analyzed. Follow-up and mortality analyses were assessed using the Cox regression model. The mean age was 43.9 ± 12.9 years, 64% were males, and 53% were diabetics. The median OPG was 11.28 (IQR: 7.6−17.4 pmol/L), and 42% of cases had cardiovascular calcifications. The median VC was 424 (IQR:101−886). During follow-up (23 ± 7 months), there were 34 deaths, and 44% were cardiovascular in origin. In multivariable analysis, OPG was a significant predictor for all-cause (HR 1.08; p < 0.002) and CV mortality (HR 1.09; p < 0.013), and performed better than VC (HR 1.00; p < 0.62 for all-cause mortality and HR 1.00; p < 0.16 for CV mortality). For each mg/dL of albumin-corrected calcium, there was an increased risk for CV mortality, and each g/dL of albumin decreased the risk factor for all-cause mortality. OPG levels above 14.37 and 13.57 pmol/L showed the highest predictive value for all-cause and CV mortality in incident PD patients and performed better than VC.

Kt/V reach rate is associated with clinical outcome in incident peritoneal dialysis patients

Background

The urea clearance index (Kt/V) is an important index for predicting the clinical outcome of peritoneal dialysis (PD) patients, but it changes with time depending on the clinical condition. This study aimed to investigate the association between the Kt/V reach rate (defined as the percentage of Kt/V measurements that reached ≥ 1.70) and clinical outcome in incident PD patients.

Methods

In this retrospective cohort study, 210 patients were enrolled from the First Affiliated Hospital of Zhengzhou University from 1 January 2013 to 31 October 2019. The target Kt/V reach rate in the first year was applied as the predictor variable. Kaplan-Meier survival curves were drawn to evaluate differences in prognosis. The association between Kt/V reach rate and the composite clinical outcome (death or transfer to hemodialysis) was tested by Cox regression analysis.

Results

The dialysis adequacy group (Kt/V reach rate 3/3 times) and the dialysis intermittent adequacy group (1/3 or 2/3 times) had significantly better clinical outcomes than the dialysis inadequacy group (0/3 times). There was no difference in clinical outcome between the lower-rate group (reach rate 1/3 times) and the higher-rate group (2/3 times). Compared with the dialysis inadequacy group, the dialysis intermittent adequacy group and dialysis adequacy group had significantly lower risks of the composite outcome (HR 0.487, 95% CI 0.244–0.971, p = 0.041; HR 0.150, 95% CI 0.043–0.520, p = 0.003) in the fully adjusted analysis.

Conclusion

Higher Kt/V reach rates are associated with a better prognosis in incident PD patients.

Peritoneal dialysis adequacy: a paradigm shift

For the past 30 years, nephrologists have focused on a single minimal threshold of Kt/V_urea to determine the adequacy of peritoneal dialysis (PD). To date, there is no evidence that shows Kt/V_urea to be a good surrogate measure of uremic symptom control or nutritional state in patients on PD. Volume of distribution (V_urea) generally is considered equivalent to total body water (TBW). Yet, accurate determination of TBW is difficult. The most recent International Society for Peritoneal Dialysis practice recommendations on prescribing high-quality PD emphasized incorporation of multiple measures rather than the single value of Kt/V_urea. These measures include shared decision-making between the patient and the care team and assessment of health-related quality of life, burden of uremic symptoms, presence of residual kidney function, volume status, and biochemical measures including serum potassium and bicarbonate levels. In some cases, PD prescriptions can be tailored to the patient priorities and goals of care, such as in frail and pediatric patients. Overall, there has been a paradigm shift in providing high-quality care to PD patients. Instead of focusing on small solute clearance in the form of Kt/V_urea, nephrologists are encouraged to use a more comprehensive assessment of the patient as a whole.

Clinical feasibility of transfer to combined therapy with peritoneal dialysis and hemodialysis for patients on peritoneal dialysis: A prospective multicenter study in Japan

INTRODUCTION

Although combined therapy with peritoneal dialysis (PD) and hemodialysis (HD) is widespread in Japan, its clinical utility has been reported only in retrospective or before-and-after test lacking a control group.

METHODS

We conducted a prospective, multicenter, observational cohort study of 176 incident PD patients and compared patient survival and changes in clinical parameters between patients on different dialysis modalities.

RESULTS

During a median follow-up of 41 months, 47 patients transferred to combined therapy and 35 patients transferred directly to HD. Patients transferred to combined therapy had a significantly better survival than those transferred directly to HD. However, we could not establish this difference in a multivariate analysis because only six patients died among these groups. The decreases in urea nitrogen and serum creatinine were more prominent among patients directly transferred to HD.

CONCLUSION

This is the first report revealing clinical feasibility of transfer to combined therapy for PD patients.

Polypharmacy Predicts Onset and Transition of Frailty, Malnutrition, and Adverse Outcomes in Peritoneal Dialysis Patient

BACKGROUND

Polypharmacy, frailty and malnutrition are known predictors of adverse outcomes in dialysis patients. Little has reported about their interaction and composite prognostic values. We aimed to describe the interaction between polypharmacy, frailty, nutrition, hospitalization, and survival in peritoneal dialysis patients.

METHODS

In this prospective cohort study, we recruited 573 peritoneal dialysis patients. Drug burden was measured by medication number and daily pill load. Frailty and nutrition were assessed by the validated Frailty Score (FQ) and Subjective Global Assessment (SGA) respectively. All patients were followed for two years. Primary outcome was all-cause mortality. Secondary outcomes were fall and fracture episodes, hospitalization, change in FQ and SGA.

RESULTS

At baseline, each patient took 7.5 ± 2.6 medications with 15.5 ± 8.5 tablets per day. Medication number, but not daily pill load predicted baseline FQ (p = 0.004) and SGA (p = 0.03). Over 2 years, there were 69 fall and 1,606 hospitalization episodes. In addition, 148 (25.8%) patients died, while FQ and SGA changed by 0.73 ± 4.23 and -0.07 ± 1.06 respectively in survivors. Medication number (hospitalization: p = 0.02, survival: p = 0.005), FQ (hospitalization: p < 0.001; survival: p = 0.01) predicted hospitalization and survival. Medication number also predicted fall episodes (p = 0.02) and frailty progression (p = 0.002). Daily pill load did not predict any of these outcomes.

CONCLUSIONS

Drug burden is high in peritoneal dialysis patients, and it carries important prognostic implication. Medication number but not pill load significantly predicted onset and progression of frailty, malnutrition, fall, hospitalization, and mortality.

Regression of Left Ventricular Hypertrophy in Patients Combined with Peritoneal Dialysis and Hemodialysis

METHODS

This retrospective study enrolled 58 patients at The Second Affiliated Hospital of Soochow University who switched from PD to PHD. Clinical data and echocardiographic examination results were collected. Data from the two groups with a normal distribution were compared with the paired t-test. A pvalue <0.05 (two-tailed) was considered statistically significant.

RESULTS

A total of 58 subjects were enrolled, including 46 males and 12 females, with a median age of 50.2 ± 11.1 (47-68) years. The mean duration of peritoneal dialysis was 67.2 ± 33.6 months. Before and after PHD, the ultrafiltration volume (p = 0.021) and hemoglobin (p = 0.001) were increased, while SBP (p = 0.002), DBP (p = 0.002), phosphorus (p < 0.001), and ESA dosage (p < 0.001) were decreased. Before and after combined dialysis (PHD), the incidence of LVH was 76.4% and 61.8%, respectively (p = 0.013), and LVMI decreased from 173.8 ± 86.2 g/m² to 160.6 ± 78.5 g/m² (p < 0.001).

CONCLUSION

Compared with PD alone, the combination of PD and HD resulted in regression of LVH and reduced LVMI.

Change in Anemia by Carnitine Supplementation in Patients Undergoing Peritoneal Dialysis: A Retrospective Observational Study

Background: Carnitine supplementation improves various dialysis-related symptoms including erythropoietin-resistant anemia in patients who are undergoing hemodialysis. However, the utility of carnitine supplementation in patients who are undergoing peritoneal dialysis (PD) is not fully understood.

Methods: Thirteen patients undergoing PD [mean age: 54.2 ± 14.8 years, males: 9/13 (69%)] administered oral carnitine supplementation (mean dose: 9.1 ± 3.3 mg/kg/day) for 4–6 months were retrospectively investigated. Changes in serum carnitine levels and other clinical variables including the erythropoietin resistance index (ERI) were analyzed after carnitine supplementation.

Results: Carnitine supplementation increased serum total carnitine (48.5 ± 10.2 vs. 130.1 ± 37.2 μmol/L, P < 0.01), free carnitine (31.1 ± 8.3 vs. 83.1 ± 24.6 μmol/L, P < 0.01), and acyl carnitine (17.4 ± 2.8 vs. 46.9 ± 13.8, P < 0.01) levels. The acyl carnitine/free carnitine ratio was not affected (0.6 ± 0.1 vs. 0.6 ± 0.1, P = 0.75). Although the mean ERI was not affected by carnitine supplementation [13.7 ± 4.7 vs. 11.6 ± 3.4 IU/kg/(g/dL)/week, P = 0.28], the ERI change rate was significantly decreased (1.00 ± 0.00 vs. 0.87 ± 0.11, P < 0.01).

Conclusion: Carnitine supplementation may improve erythropoietin resistance in patients who are undergoing PD.

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.

Traduction des Recommandations de l'ISPD pour l'évaluation du dysfonctionnement de la membrane péritonéale chez l'adulte

Informations concernant cette traductionDans le cadre d’un accord de partenariat entre l’ISPD et le RDPLF, le RDPLF est le traducteur français officiel des recommandations de l’ISPD. La traduction ne donne lieu à aucune compensation financière de la part de chaque société et le RDPLF s’est engagé à traduire fidèlement le texte original sous la responsabilité de deux néphrologues connus pour leur expertise dans le domaine. Avant publication le texte a été soumis à l’accord de l’ISPD. La traduction est disponible sur le site de l’ISPD et dans le Bulletin de la Dialyse à Domicile.Le texte est, comme l’original, libremement téléchargeable sous licence copyright CC By 4.0https://creativecommons.org/licenses/by/4.0/Cette traduction est destinée à aider les professionnels de la communauté francophone à prendre connaissance des recommandations de l’ISPD dans leur langue maternelle. Toute référence dans un article doit se faire au texte original en accès libre :Peritoneal Dialysis International https://doi.org/10.1177/0896860820982218 Dans les articles rédigés pour des revues françaises, conserver la référence à la version originale anglaise ci dessus, mais ajouter «version française  https://doi.org/10.25796/bdd.v4i3.62673"»TraducteursDr Christian Verger, néphrologue, président du RDPLFRDPLF, 30 rue Sere Depoin, 95300 Pontoise – FranceProfesseur Max Dratwa, néphrologueHôpital Universitaire Brugmann – Bruxelles – Belgique

Estimating total small solute clearance in patients treated with continuous ambulatory peritoneal dialysis without urine and dialysate collection

BACKGROUND

International Society for Peritoneal Dialysis guidelines recommend to routinely monitor the total measured clearance (mCl) of small solutes such as creatinine; however, collection of 24-h urine and peritoneal dialysis (PD) fluid is burdensome to patients and prone to errors. We hypothesized that equations could be developed to estimate mCl (estimated clearance (eCl)) using endogenous filtration markers.

METHODS

In the Guangzhou PD Study (n = 980), we developed eCl equations using linear regression in two-third and validated them in the remaining one-third. Reference tests were mCl for urea nitrogen (UN) (mCl_UN, ml/min) and average mCl for UN and creatinine (mCl_UN-cr, ml/min/1.73 m²). Index tests were various eCl equations using UN, creatinine, low-molecular-weight proteins (LMWPs) (beta-trace protein (BTP), beta-2 microglobulin (B2M), and cystatin C), demographic variables, and body size. After reexpression of the equations in the combined data set, we analyzed accuracy (eCl within ± 2.0 units of mCl) and the predictive value of eCl to detect a weekly total standard Kt/V (weekly mCl_UN indexed for total body water) > 1.7 using receiver operating characteristic curve.

RESULTS

Mean age of the cohort was 50 ± 15 years, 53% were male; mCl_UN was 6.9 ± 1.8 and mCl_UN-cr was 7.5 ± 2.8. Creatinine but not UN contributed to eCl for both mCl. LMWP did not improve accuracy for mCl_UN (range 88-89%). BTP and B2M improved the accuracy for mCl_UN-cr (82% vs. 80%); however, differences were small. The area under the curve for predicting a weekly Kt/V > 1.7 was similar for all equations (range 0.79-0.80).

CONCLUSIONS

Total small solute clearance can be estimated moderately well in continuous ambulatory PD patients using serum creatinine and demographic variables without urine and dialysate collection.

ISPD recommendations for the evaluation of peritoneal membrane dysfunction in adults: Classification, measurement, interpretation and rationale for intervention

Lay summary

Peritoneal dialysis (PD) uses the peritoneal membrane for dialysis. The peritoneal membrane is a thin layer of tissue that lines the abdomen. The lining is used as a filter to help remove extra fluid and poisonous waste from the blood. Everybody is unique. What is normal for one person’s membrane may be very different from another person’s. The kidney care team wants to provide each person with the best dialysis prescription for them and to do this they must evaluate the person’s peritoneal lining. Sometimes dialysis treatment itself can cause the membrane to change after some years. This means more assessments (evaluations) will be needed to determine whether the person’s peritoneal membrane has changed. Changes in the membrane may require changes to the dialysis prescription. This is needed to achieve the best dialysis outcomes. A key tool for these assessments is the peritoneal equilibration test (PET). It is a simple, standardized and reproducible tool. This tool is used to measure the peritoneal function soon after the start of dialysis. The goal is to understand how well the peritoneal membrane works at the start of dialysis. Later on in treatment, the PET helps to monitor changes in peritoneal function. If there are changes between assessments causing problems, the PET data may explain the cause of the dysfunction. This may be used to change the dialysis prescription to achieve the best outcomes. The most common problem with the peritoneal membrane occurs when fluid is not removed as well as it should be. This happens when toxins (poisons) in the blood cross the membrane more quickly than they should. This is referred to as a fast peritoneal solute transfer rate (PSTR). Since more efficient fluid removal is associated with better outcomes, developing a personal PD prescription based on the person’s PSTR is critically important. A less common problem happens when the membrane fails to work properly (also called membrane dysfunction) because the peritoneal membrane is less efficient, either at the start of treatment or developing after some years. If membrane dysfunction gets worse over time, then this is associated with progressive damage, scarring and thickening of the membrane. This problem can be identified through another change of the PET. It is called reduced ‘sodium dip’. Membrane dysfunction of this type is more difficult to treat and has many implications for the individual. If the damage is major, the person may need to stop PD. They would need to begin haemodialysis treatment (also spelled hemodialysis). This is a very important and emotional decision for individuals with kidney failure. Any decision that involves stopping PD therapy or transitioning to haemodialysis therapy should be made jointly between the clinical team, the person on dialysis and a caregiver, if requested. Although evidence is lacking about how often tests should be performed to determine peritoneal function, it seems reasonable to repeat them whenever there is difficulty in removing the amount of fluid necessary for maintaining the health and well-being of the individual. Whether routine evaluation of membrane function is associated with better outcomes has not been studied. Further research is needed to answer this important question as national policies in many parts of the world and the COVID-19 has placed a greater emphasis and new incentives encouraging the greater adoption of home dialysis therapies, especially PD. For Chinese and Spanish Translation of the Lay Summary, see Online Supplement Appendix 1.

Key recommendations

Guideline 1:

A pathophysiological taxonomy: A pathophysiological classification of membrane dysfunction, which provides mechanistic links to functional characteristics, should be used when prescribing individualized dialysis or when planning modality transfer (e.g. to automated peritoneal dialysis (PD) or haemodialysis) in the context of shared and informed decision-making with the person on PD, taking individual circumstances and treatment goals into account. (practice point)

Guideline 2a:

Identification of fast peritoneal solute transfer rate (PSTR): It is recommended that the PSTR is determined from a 4-h peritoneal equilibration test (PET), using either 2.5%/2.27% or 4.25%/3.86% dextrose/glucose concentration and creatinine as the index solute. (practice point) This should be done early in the course dialysis treatment (between 6 weeks and 12 weeks) (GRADE 1A) and subsequently when clinically indicated. (practice point)

Guideline 2b:

Clinical implications and mitigation of fast solute transfer: A faster PSTR is associated with lower survival on PD. (GRADE 1A) This risk is in part due to the lower ultrafiltration (UF) and increased net fluid reabsorption that occurs when the PSTR is above the average value. The resulting lower net UF can be avoided by shortening glucose-based exchanges, using a polyglucose solution (icodextrin), and/or prescribing higher glucose concentrations. (GRADE 1A) Compared to glucose, use of icodextrin can translate into improved fluid status and fewer episodes of fluid overload. (GRADE 1A) Use of automated PD and icodextrin may mitigate the mortality risk associated with fast PSTR. (practice point)

Guideline 3:

Recognizing low UF capacity: This is easy to measure and a valuable screening test. Insufficient UF should be suspected when either (a) the net UF from a 4-h PET is <400 ml (3.86% glucose/4.25% dextrose) or <100 ml (2.27% glucose /2.5% dextrose), (GRADE 1B) and/or (b) the daily UF is insufficient to maintain adequate fluid status. (practice point) Besides membrane dysfunction, low UF capacity can also result from mechanical problems, leaks or increased fluid absorption across the peritoneal membrane not explained by fast PSTR.

Guideline 4a:

Diagnosing intrinsic membrane dysfunction (manifesting as low osmotic conductance to glucose) as a cause of UF insufficiency: When insufficient UF is suspected, the 4-h PET should be supplemented by measurement of the sodium dip at 1 h using a 3.86% glucose/4.25% dextrose exchange for diagnostic purposes. A sodium dip ≤5 mmol/L and/or a sodium sieving ratio ≤0.03 at 1 h indicates UF insufficiency. (GRADE 2B)

Guideline 4b:

Clinical implications of intrinsic membrane dysfunction (de novo or acquired): in the absence of residual kidney function, this is likely to necessitate the use of hypertonic glucose exchanges and possible transfer to haemodialysis. Acquired membrane injury, especially in the context of prolonged time on treatment, should prompt discussions about the risk of encapsulating peritoneal sclerosis. (practice point)

Guideline 5:

Additional membrane function tests: measures of peritoneal protein loss, intraperitoneal pressure and more complex tests that estimate osmotic conductance and ‘lymphatic’ reabsorption are not recommended for routine clinical practice but remain valuable research methods. (practice point)

Guideline 6:

Socioeconomic considerations: When resource constraints prevent the use of routine tests, consideration of membrane function should still be part of the clinical management and may be inferred from the daily UF in response to the prescription. (practice point)

Normalized Protein Catabolic Rate Is a Superior Nutritional Marker Associated With Dialysis Adequacy in Continuous Ambulatory Peritoneal Dialysis Patients

Introduction: Current knowledge of the relationship between normalized protein catabolic rate (nPCR) and dialysis adequacy is limited. Our study aimed to explore the potential relationship between nPCR and dialysis adequacy.

Methods: In this cross-sectional study, we analyzed the association of nPCR with peritoneal dialysis adequacy in 266 continuous ambulatory peritoneal dialysis (CAPD) patients (mean age 48.6 ± 13.1 years; 50.8% male). The patients were divided into two groups: a dialysis inadequacy group (total weekly Kt/V urea < 1.70) and a dialysis adequacy group (total weekly Kt/V urea≥1.70). We then analyzed the correlation between dialysis adequacy and the patients' primary cause of end-stage renal disease, nutritional and inflammatory markers, and biochemical parameters. Multivariable logistic regression analysis was also used to identify risk factors for inadequate dialysis.

Results: We observed a significantly higher level of nPCR (0.98 ± 0.22 vs. 0.79 ± 0.18 g/kg/day, p < 0.001) in the dialysis adequacy group, whereas we observed no significant differences among other nutritional markers such as albumin, prealbumin, and transferrin. Correlation analyses revealed that dialysis adequacy was positively associated with residual glomerular filtration rate (rGFR), hemoglobin, serum calcium, and body mass index (BMI), while dialysis adequacy was negatively associated with leak-protein, uric acid, high-sensitivity C-reactive protein, interleukin-6, and serum phosphorus. Furthermore, a logistic regression analysis revealed that gender (male), nPCR <0.815 g/kg/day, higher weight, and rGFR <2.43 mL/min/1.73 m² were independent risk factors for inadequate dialysis.

Conclusion: Nutritional status is closely associated with dialysis adequacy. Among common nutritional markers, nPCR may be superior for predicting CAPD dialysis adequacy. Gender (male), nPCR <0.815 g/kg/day, higher weight, and rGFR <2.43 mL/min/1.73 m² are independent risk factors for dialysis inadequacy in CAPD patients.

KDOQI US Commentary on the 2020 ISPD Practice Recommendations for Prescribing High-Quality Goal-Directed Peritoneal Dialysis

The recently published 2020 International Society for Peritoneal Dialysis (ISPD) practice recommendations regarding prescription of high-quality goal-directed peritoneal dialysis differ fundamentally from previous guidelines that focused on "adequacy" of dialysis. The new ISPD publication emphasizes the need for a person-centered approach with shared decision making between the individual performing peritoneal dialysis and the clinical care team while taking a broader view of the various issues faced by that individual. Cognizant of the lack of strong evidence for the recommendations made, they are labeled as "practice points" rather than being graded numerically. This commentary presents the views of a work group convened by the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) to assess these recommendations and assist clinical providers in the United States in interpreting and implementing them. This will require changes to the current clinical paradigm, including greater resource allocation to allow for enhanced services that provide a more holistic and person-centered assessment of the quality of dialysis delivered.

Targeting Uremic Toxins to Prevent Peripheral Vascular Complications in Chronic Kidney Disease

Chronic kidney disease (CKD) exhibits progressive kidney dysfunction and leads to disturbed homeostasis, including accumulation of uremic toxins, activated renin-angiotensin system, and increased oxidative stress and proinflammatory cytokines. Patients with CKD are prone to developing the peripheral vascular disease (PVD), leading to poorer outcomes than those without CKD. Cumulative evidence has showed that the synergy of uremic milieu and PVD could exaggerate vascular complications such as limb ischemia, amputation, stenosis, or thrombosis of a dialysis vascular access, and increase mortality risk. The role of uremic toxins in the pathogenesis of vascular dysfunction in CKD has been investigated. Moreover, growing evidence has shown the promising role of uremic toxins as a therapeutic target for PVD in CKD. This review focused on uremic toxins in the pathophysiology, in vitro and animal models, and current novel clinical approaches in reducing the uremic toxin to prevent peripheral vascular complications in CKD patients.

Therapeutic Options for Preservation of Residual Renal Function in Patients on Peritoneal Dialysis

Dialysis is not the ideal renal replacement therapy because it does not fully restore all kidney functions. Increasing evidence suggests that preservation of residual renal function is associated with a survival benefit, a decrease in morbidity, better nutrition, a lower level of inflammatory markers, an improved quality of life, and cost savings by obviating the need for more peritoneal dialysis exchanges and possibly by reducing the requirement for antihypertensive agents, phosphate binders, and erythropoietin. In the present article, we review the impact of residual renal function on patient outcomes and the renoprotective strategies available in patients on peritoneal dialysis.

30 Years of Peritoneal Dialysis Development: The past and the Future

A review is given of 30 years of development in peritoneal dialysis (PD). After a short description of the first 20 years, the main emphasis is put on the last 10 years. Subjects discussed are the increasing use of PD in high-risk populations, peritonitis and other catheter-related problems, adequacy of dialysis and nutrition, patient outcomes in comparison with hemodialysis, and peritoneal membrane changes with time on PD. Topics that have emerged during the last decade and the challenges for the next decennium are discussed. The great importance of quality assurance in fast-growing PD populations and of prevention of long-term membrane alterations are emphasized.

Peritoneal Dialysis Utilization and Outcome: What are we Facing?

Penetration of peritoneal dialysis (PD) varies tremendously across the world. It ranges from about 80% in Hong Kong and Mexico to just a few percentage points in the United States, Japan, and Germany. While PD is growing in China, India, and some Eastern European and South American countries, it is declining in many European and North American countries. In terms of outcomes, the survival of PD patients is generally comparable to that of hemodialysis (HD) patients and better than that of HD patients during the first few years on dialysis. According to the U.S. Renal Data System, survival of patients on PD has been improving faster than that of patients on HD. In terms of cost, PD is usually cheaper than HD. Hence, declining PD utilization is unjustified. Work is required to identify and overcome negative factors such as physician bias, unfair medical reimbursement systems, and poor patient education.

The Most Recent Trends of Peritoneal Dialysis in Japan

By 31 December 2006, more than 260 000 patients were on dialysis therapy in Japan, and 9243 of them (3.6%) were on peritoneal dialysis (PD). The mean age of PD patients was 5 years less than that of all patients with chronic kidney disease, and the prevalence of diabetes among them was 9.4% lower. Among the PD patients, 18.0% were being treated with a combination of PD and hemodialysis, and 33.4% were being treated with automated PD. A peritoneal equilibration test (PET) had been performed in 22.0% of the patients, who were then classified into the four PET categories. Of the tested patients, 10.3% were placed in the low (L) category; 38.3% in the low-average (LA) category; 38.4%, in the high-average (HA) category; and 13.0%, in the high (H) category. Icodextrin was used by 27.3% of patients classified L, 30.5% of those classified LA, 47.1% of those classified HA, and 55.1% of those classified H. The annual death rate was 6.1%, which was lower than the rate for HD (9.7%); and the annual withdrawal rate was 19.8%. Infectious complications were the main cause for lowered rates of patient and technique survival. Use of PD for older and diabetic patients and of combination therapy with hemodialysis are key perspectives in the most recent report on PD in Japan.

Serum Zinc Concentration Correlates With Ferritin Concentration in Patients Undergoing Peritoneal Dialysis: A Cross-Sectional Study

Background: Zinc deficiency is common and is associated with erythropoietin resistant anemia, dysgeusia, and hypogonadism in patients undergoing hemodialysis. However, the prevalence and clinical effects of zinc deficiency in patients undergoing peritoneal dialysis (PD) have not been determined. Methods: This was a retrospective, cross-sectional study. The prevalence of serum zinc deficiency and the clinical factors related to serum zinc concentration were determined in 49 patients undergoing PD [mean age 59.5 years (±14.8 years), 38/49 were men (78.6%), median PD period 24.0 months (12.5-45.0 months)]. A serum zinc concentration <60 μg/dL was defined as serum zinc deficiency, and a serum zinc concentration between 60 and 80 μg/dL as possible serum zinc deficiency. Results: Serum zinc deficiency was present in 51% (25/49) of the patients, and possible serum zinc deficiency was present in 45% (22/49) of patients undergoing PD. Multivariate analysis showed that serum zinc concentration significantly correlated with serum ferritin concentration (β = 0.357, P < 0.01). Conclusions: The prevalences of serum zinc deficiency and possible serum deficiency are high and serum zinc concentration correlates with serum ferritin concentration in patients undergoing PD.

High Levels of Physical Activity May Promote a Reduction in Bone Mineral Density in Peritoneal Dialysis

Background and objectives: Peritoneal dialysis (PD) patients are expected to present lower levels of physical activity, unhealthy changes at the body composition level, and low levels of strength. Firstly, this study aimed to report the sex differences in physical activity, body composition and muscle strength and the relations among these variables. Secondly, we analyze the relationship between physical activity and biochemical parameters. Materials and Methods: Thirty-four patients (13 women and 21 men) participated in this study. Body composition was assessed by bioimpedance and dual-energy X-ray absorptiometry (DXA), and maximum isokinetic unilateral strength, analytical parameters and physical activity levels were evaluated. Results: The men showed higher values for weight, height, lean body mass, bone mineral content, bone mineral density (BMD) and total body water, while women showed higher values for the percentage of fat mass and hydration of lean body mass (p < 0.05). No differences between the sexes were found in different levels of physical activity; however, males registered significantly higher values for isokinetic strength variables except for knee extensor strength. BMD was positively related to sedentary activity and negatively related to moderate and vigorous activity (r = 0.383 and r = -0.404, respectively). Light physical activity was negatively correlated with albumin (r = -0.393) and total protein (r = -0.410) levels, while moderate/vigorous activity was positively correlated with urea distribution volume (r = 0.446) and creatinine clearance (r = 0.359) and negatively correlated with the triglyceride level (r = -0.455). Conclusions: PD patients with higher levels of physical activity present better results in terms of body composition and biochemical parameters. Additional studies should be conducted to clarify the relation between physical activity level and BMD.

Utility of serum beta-trace protein as a tool for estimating residual kidney function in peritoneal dialysis patients

BACKGROUND

Beta-trace protein (BTP) is a novel marker for residual kidney function (RKF) without need for urinary collection. We aimed to examine its utility as a tool for estimating RKF in incident peritoneal dialysis (PD) patients.

METHODS

This was a post hoc analysis of incident PD patients from the balANZ trial cohort. The outcomes evaluated were trends of serum BTP concentration with time, factors associated with change in BTP using mixed-effect multilevel linear regression and correlation of BTP with mean urinary urea and creatinine clearances (measured glomerular filtration rate (GFR)). Performances of two BTP-derived equations (Shafi-Eqn and Steubl-Eqn) to estimate GFR were evaluated by reporting bias (median difference between estimated and measured GFR), precision (interquartile range of median bias), accuracy (±2 mL/min of measured GFR) and P30 (percentage estimates within 30% of measured GFR) with confidence intervals (CIs) generated by bootstrapping 2000 replicates. The agreement between BTP-estimated GFR and measured GFR was also plotted graphically on Bland-Altman analysis.

RESULTS

The study included 161 PD patients. BTP concentration increased with dialysis vintage and was inversely correlated with measured GFR (r = -0.64). Larger increases in BTP were associated with longer PD vintage and higher dialysate glucose exposure. Biases of BTP-estimated GFRs (Shafi-Eqn and Steubl-Eqn) were 1.2 mL/min/1.73 m² (95% CI 1.0-1.3 mL/min/1.73 m²) and 0.4 mL/min/1.73 m² (95% CI 0.2-0.6 mL/min/1.73 m²), respectively. Both BTP-estimated GFRs had poor precision (3.2 mL/min/1.73 m² (95% CI 2.9-3.5 mL/min/1.73 m²) and 2.8 mL/min/1.73 m² (95% CI 2.5-3.2 mL/min/1.73 m²), respectively) and accuracy of estimates (55% (95% CI 52-60%) and 59% (95% CI 55-63%), respectively). The mean difference of BTP-estimated GFR (Shafi-Eqn and Steubl-Eqn) and measured GFR were -1.14 mL/min/1.73 m² and -0.42 mL/min/1.73 m², respectively, with large limit of agreement on Bland-Altman plot.

CONCLUSIONS

Serum BTP level was inversely related to RKF but neither BTP-estimated GFR equations were sufficiently accurate for routine use in PD patients.

Automated Remote Monitoring for Peritoneal Dialysis and Its Impact on Blood Pressure

Introduction: Peritoneal dialysis (PD) provides a safe, home-based continuous renal replacement therapy for patients. The adherence of the patients to the prescribed dialysis fluids cannot always be monitored by physicians. Remote monitoring automated peritoneal dialysis (RM-APD) can affect patients’ compliance with treatment and, thus, clinical outcomes. Objective: We aimed to evaluate the clinical outcomes of patients with a remote access program. Methods: This was an observational study. We analyzed the effect of RM-APD on treatment adherence, dialysis adequacy, and change in blood pressure control, sleep quality, and health-related quality of life during the 6 months of follow-up. Results: A total of 15 patients were enrolled in this study. It was found that there was a significant decrease (99 ± 19 vs. 89 ± 11 mm Hg) in mean arterial blood pressure of patients, and a considerable increase in Kt/V was observed in the sixth month after the RM-APD switch (2.11 ± 0.4 vs. 2.25 ± 0.5). A significant increase was found when comparing the 3-month and 6-month ultrafiltration amounts before RM-APD and the ultrafiltration amount within 6 months after RM-APD (800 mL [500–1,000] and 752 mL [490–986] vs. 824 mL [537–1,183]). The daily antihypertensive pill need (4 [0–7] vs. 2 [0–6]) and alarms received from the device decreased (from 4 [3–8] to 2 [0–3]) at the sixth month of the switch. There was no significant change in sleep quality and health-related quality of life within 6 months. Conclusion: This study showed that treatment adherence and ultrafiltration amounts of patients increased with the use of RM-APD, as well as better blood pressure control with fewer antihypertensive drugs.

Flexibility in peritoneal dialysis prescription: Impact on technique survival

Background:

Patient burnout is a major cause of technique failure on peritoneal dialysis (PD). Reducing the PD prescription on an individual basis, dependent upon residual kidney function (RKF), may have a role in prolonging time on PD by reducing dialysis burden. This retrospective study aimed to determine the safety and impact of flexible PD prescribing on technique and patient survival.

Methods:

All patients (186) from our centre starting PD from 1st January 2012 to 31st December 2016 were included. Data on dialysis prescription were collected for each patient from the time they had started PD, and dialysis adequacy measured regularly (3–6 monthly) using PD Adequest.

Results:

Median age at start of dialysis was 61 years. Only 49% started on PD 7 days a week and this dropped to 27% at 3 months following the first clearance test. Over 90% achieved creatinine clearance > 50 L/week/1.73 m2 up to 2 years of follow-up, with 87% achieving this standard at 3 years. Patient and technique survival at 1, 2 and 3 years were 91%, 81%, and 72%, and 89%, 87% and 78% respectively. Factors on univariate analysis affecting technique survival included increasing age (HR 0.98, p = 0.04, 95% CI (0.96–0.999)), two or more episodes of PD-associated peritonitis (HR 4.52, p = 0.00, 95% CI (1.87–10.91)) and increasing PD intensity (HR 3.30, p = 0.02, 95% CI (1.22–8.93)). After multivariate adjustment which included baseline kidney function, low PD intensity continued to be associated with better technique survival (HR 0.17, p = 0.03, 95% CI (0.03–0.85)).

Conclusion:

Tailoring the PD prescription to RKF enables days off dialysis while still maintaining recommended levels of small solute clearance. This approach reduces dialysis burden and is associated with higher technique survival.

Development of a framework for minimum and optimal safety and quality standards for hemodialysis and peritoneal dialysis

Substantial heterogeneity in practice patterns around the world has resulted in wide variations in the quality and type of dialysis care delivered. This is particularly so in countries without universal standards of care and governmental (or other organizational) oversight. Most high-income countries have developed such oversight based on documentation of adherence to standardized, evidence-based guidelines. Many low- and lower-middle-income countries have no or only limited organized oversight systems to ensure that care is safe and effective. The implementation and oversight of basic standards of care requires sufficient infrastructure and appropriate workforce and financial resources to support the basic levels of care and safety practices. It is important to understand how these standards then can be reasonably adapted and applied in low- and lower-middle-income countries.

Peritoneal Dialysis in the Sudan

Background

End-stage renal disease is a significant social and economic burden on the Sudan. Continuous ambulatory peritoneal dialysis (CAPD) was recently introduced as a national service and is provided free of charge by the Federal State. We present here an overview of our experience and outcomes after the first 20 months of operation of the National Program, displaying its organization and patient and technique survival, peritonitis rates, and adequacy parameters of the first patients to undergo CAPD.

Methods

As a national experiment, the program was sequentially launched in 5 adult and 2 pediatric centers in Khartoum, the capital city of the country. The data include the entire 111 patients who underwent CAPD from June 2005 to January 2007. All data were reported to, and analyzed at, the head office of the Sudan National Peritoneal Dialysis Program.

Results

CAPD is the modality exclusively utilized thus far. Automated PD will be added to the program this year. By 30 January 2007, the total number of patients enrolled was 111. Their age range was 1 – 75 (median 56) years. 20 patients (18%) were shifted to hemodialysis and 5 patients received living related kidney transplants. Two died of severe septicemia due to peritonitis; 16 (14%) others died of non-PD-related causes. There were 60 cases of peritonitis in 839 patient-months, which equates to an overall peritonitis rate of 1 episode every 14 months (0.87 episodes per year at risk). The individual center rates varied. A critical review of cases at the end of the first year showed a statistically significant age difference, with peritonitis being more common in the younger patients. Mean age of patients that developed peritonitis was 30.53 years, whereas that for peritonitis-free patients was 44.09 years ( p = 0.025). All patients that had peritonitis presented with abdominal pain and had a cloudy effluent; none had exit-site or tunnel infection. The culture-negative peritonitis rate was 53%. Pseudomonas species were responsible for 13.3% and Staphylococcus aureus for 6.7%. Touch contamination was the likely mechanism behind 46.7% of the episodes. There were 3 cases of refractory peritonitis and a single case of relapsing peritonitis. Concerning PD adequacy, average Kt/V urea was 1.74; weekly creatinine clearance was 62.5 L/1.73 m2. Average normalized protein catabolic rate, as a measure of dietary protein intake in patients in a steady state, was 1.17 g/kg. These measures indicate that the overall program adequacy was satisfactory and the values fall within the recommended ranges.

Conclusion

The first 20 months of operation of the Sudan's National Peritoneal Dialysis Program have proven that it is a promising project with multifaceted success. The adequacy indicators are acceptable but the cumulative peritonitis incidence is above that recommended, indicating several areas for potential improvement. Although CAPD is highly cost-effective, ongoing difficulties, including the cost of medications and laboratory tests, are being sorted out with official support and public involvement.

Peritonitis in Peritoneal Dialysis Patients in Uruguay

Uruguay is a South American country (3241003 inhabitants) where renal replacement treatment is universally available. The aim of this study was to analyze the incidence and outcome of peritonitis, and the causative organisms and their sensitivity, in order to recommend an empiric initial antibiotic treatment. A retrospective descriptive study of all peritonitis during the period 2004 – 2005 was performed (144 peritonitis, 44% due to gram-positive bacteria). We conclude that the high prevalence of methicillin-resistant coagulase-negative staphylococci justifies the use of vancomycin in the national empiric initial antibiotic protocols.

Prescribing high-quality peritoneal dialysis: Moving beyond urea clearance

Urea removal in peritoneal dialysis (PD) has been a primary measure of dialysis adequacy, but its utility remains limited due to its poor correlation with the clearance of other important uraemic retention solutes and the low certainty of evidence relating peritoneal urea clearance and survival of individuals doing PD. Indeed, clearances of other uraemic solutes, electrolyte imbalances, hypoalbuminaemia and nutritional status, may provide a more holistic measure of dialysis adequacy when evaluating individuals on PD in addition to focusing on person-centred outcomes. Here, we review the history of the urea and creatinine-centric approach to dialysis adequacy and explore the potential importance of other uraemic retention solutes, electrolyte disturbances, phosphorus control, peritoneal protein losses and hypoalbuminaemia, as well as nutritional management to promote a broader multidimensional concept of clearance for PD.

2005 Guidelines on targets for solute and fluid removal in adults being treated with chronic peritoneal dialysis: 2019 Update of the literature and revision of recommendations

BACKGROUND

The International Society for Peritoneal Dialysis guidelines for small solute clearance and fluid removal in peritoneal dialysis (PD) were published in 2005. The aim of this article is to update those guidelines by reviewing the literature that supported those guidelines and examining publications since then.

METHODS

An extensive search of publications was performed through electronic databases and a hand search through reference lists from the existing guideline and selected articles.

RESULTS

There have been no prospective intervention trials to inform the area of small solute clearance in PD since the publication of the original guideline in 2005. The trials to date are largely limited to a few prospective cohort studies and retrospective studies. These have, however, consistently demonstrated that residual renal function (RRF) is more often associated with patient outcome than peritoneal clearance. One of the few randomised controlled trials performed in this area does suggest that a weekly Kt/V of 2.27 ± 0.02 provides no statistically significant survival advantage over a weekly Kt/V of 1.80 ± 0.02. The lower limit of Kt/V is unknown but there is weak evidence to suggest that anuric people doing PD should have a weekly Kt/V of at least 1.7.

CONCLUSIONS

There continues to be very poor evidence in the area of small solute clearance and fluid removal in PD. The evidence that exists suggests that RRF is more important than peritoneal clearance and that there appears to be no survival advantage in aiming for a weekly Kt/V >1.70.

Volume management as a key dimension of a high-quality PD prescription

BACKGROUND

Appropriate volume control is one of the key goals in a peritoneal dialysis (PD) prescription. As such it is an important component of the International Society of Peritoneal Dialysis (ISPD) guideline for "High-quality PD prescription" necessitating a review of the literature on volume management. The workgroup recognized the importance of including within its scope measures of volume status and blood pressure in prescribing high-quality PD therapy.

METHODS

A Medline and PubMed search for publications addressing volume status and its management in PD since the publication of the 2015 ISPD Adult Cardiovascular and Metabolic Guidelines, from October 2014 through to July 2019, was conducted.

RESULTS

There were no randomized controlled trials on blood pressure intervention and six randomized trials of bioimpedance-guided volume management. Generally, all studies were of small sample size, short duration, and used surrogate markers as primary outcomes. As a consequence, only "practice points" were drawn. High-quality goal-directed PD prescription should aim to achieve and maintain clinical euvolemia taking residual kidney function and its preservation into account, so that both fluid removal from peritoneal ultrafiltration and urine output are considered and residual kidney function is not compromised. Blood pressure should be included as a key objective parameter in assessing the quality of PD prescription but there is currently no evidence for a specific target in PD. Clinical examination remains the keystone of routine clinical care.

CONCLUSIONS

High-quality goal-directed PD prescription should include volume management as one of the key dimensions.

International comparison of peritoneal dialysis prescriptions from the Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS)

Background:

We describe peritoneal dialysis (PD) prescription variations among Peritoneal Dialysis Outcomes and Practice Patterns Study (PDOPPS) participants on continuous ambulatory PD (CAPD) and automated PD (APD; n = 4657) from Australia/New Zealand (A/NZ), Canada, Japan, Thailand, United Kingdom (UK), and United States (US).

Results:

CAPD was more commonly used in Thailand and Japan, while APD predominated over CAPD in A/NZ, Canada, the US, and the UK. Total prescribed PD volume normalized to the surface area was the highest in Thailand and the lowest in Japan (for both APD and CAPD) and the UK (for CAPD). PD patients from Thailand had the lowest residual urine volume and residual renal urea clearance, yet achieved the highest dialysis urea clearance. Japanese patients had the lowest dialysis urea clearances for both APD and CAPD. Despite having similar urine volumes to patients in A/NZ, Canada, Japan, and the UK, US CAPD and APD patients used 2.5% and 3.86% glucose PD solutions more frequently, whereas fewer than 25% of these patients used icodextrin. Over half of the patients in A/NZ, Canada, the UK, and Japan used icodextrin, whereas it was hardly used in Thailand. Japan and Thailand were more likely to use 1.5% glucose solutions for their PD prescription.

Conclusions:

There are considerable international variations in PD modality use and prescription patterns that translate into important differences in achieved dialysis clearances. Ongoing recruitment of additional PDOPPS participants and accrual of follow-up time will allow us to test the associations between specific PD prescription regimens and clinical and patient-reported outcomes.

Accuracy of the estimation of V and the implications this has when applying Kt/Vurea for measuring dialysis dose in peritoneal dialysis

Background:

Current guidelines for the prescription of peritoneal dialysis dose rely on a single cut-off ‘minimal’ value of K t/ V. To apply this in the clinic, this requires an accurate estimation of V, the volume of urea distribution that equates to the total body water (TBW). This analysis sought to determine the accuracy to which V can be estimated.

Methods:

A literature search was undertaken of studies comparing TBW estimation using two or three of the following methods: isotopic dilution (gold standard), anthropometric equations (e.g. Watson formula) and bioimpedance analysis. Studies of healthy and dialysis populations of all ages were included. Mean differences and 95% limits of agreement (LOA) were extracted and pooled.

Results:

In 44 studies (31 including dialysis subjects), the between-method population means were typically within 1–1.5 L of each other, although larger bias was seen when applying anthropometric equations to different racial groups. However, the 95% LOA for all comparisons were consistently wide, typically ranging ±12–18% of the TBW. For a typical individual whose TBW is 35 L with a measured K t/ V of 1.7, this translates into a range of K t/ V 1.4–2.05.

Conclusions:

There are limitations to the accuracy of estimation of V which call into question the validity of applying a single threshold K t/ V value as indicative of adequate dialysis. This should be taken into account in guideline development such that if a target K t/ V was deemed appropriate that this should be expressed as a range; alternatively single targets should be avoided and dialysis dose should be determined according to patient need.

Incremental peritoneal dialysis

Incremental peritoneal dialysis (PD) has been variably defined. It involves taking advantage of the residual renal function that is usually present at initiation of dialysis to initially prescribe less onerous lower doses of PD while still achieving individualized clearance goals. We propose that incremental PD be defined as a strategy, rather than a particular regime, in which: (1) less than standard “full-dose” PD is initially prescribed in recognition of the value of residual renal function; (2) peritoneal clearance is initially less than the individualized clearance goal but the combination of peritoneal plus renal clearance achieves or exceeds that goal clearance; and (3) there is a clear intention to increase dose of PD as renal clearance declines and/or symptoms appear.

Incremental PD by its nature lessens the workload of dialysis for those doing PD, reduces cost and exposure of the peritoneal membrane to glucose, and may lessen mechanical symptoms. Evidence that incremental PD improves clinical outcomes compared to the use of full-dose PD is lacking but one randomized controlled trial, multiple observational studies, and a systematic review all suggest that outcomes are at least as good. Given that incremental PD costs less and is inherently less onerous, it is reasonable, pending larger randomized trials, to adopt this strategy.

Urea removal strategies for dialysate regeneration in a wearable artificial kidney

The availability of a wearable artificial kidney (WAK) that provides dialysis outside the hospital would be an important advancement for dialysis patients. The concept of a WAK is based on regeneration of a small volume of dialysate in a closed-loop. Removal of urea, the primary waste product of nitrogen metabolism, is the major challenge for the realization of a WAK since it is a molecule with low reactivity that is difficult to adsorb while it is the waste solute with the highest daily molar production. Currently, no efficient urea removal technology is available that allows for miniaturization of the WAK to a size and weight that is acceptable for patients to carry. Several urea removal strategies have been explored, including enzymatic hydrolysis by urease, electro-oxidation and sorbent systems. However, thus far, these methods have toxic side effects, limited removal capacity or slow removal kinetics. This review discusses different urea removal strategies for application in a wearable dialysis device, from both a chemical and a medical perspective.

Peritoneal Dialysis

SUMMARY Peritoneal dialysis (PD) is a renal replacement therapy based on infusing a sterile solution into the peritoneal cavity through a catheter and provides for the removal of solutes and water using the peritoneal membrane as the exchange surface. This solution, which is in close contact with the capillaries in the peritoneum, allows diffusion solute transport and osmotic ultrafiltration water loss since it is hyperosmolar to plasma due to the addition of osmotic agents (most commonly glucose). Infusion and drainage of the solution into the peritoneal cavity can be performed in two ways: manually (continuous ambulatory PD), in which the patient usually goes through four solution changes throughout the day, or machine-assisted PD (automated PD), in which dialysis is performed with the aid of a cycling machine that allows changes to be made overnight while the patient is sleeping. Prescription and follow-up of PD involve characterizing the type of peritoneal transport and assessing the offered dialysis dose (solute clearance) as well as diagnosing and treating possible method-related complications (infectious and non-infectious).

Association between carnitine deficiency and the erythropoietin resistance index in patients undergoing peritoneal dialysis: a cross-sectional observational study

Carnitine deficiency contributes to developing various pathological conditions, such as cardiac dysfunction, muscle weakness, and erythropoietin-resistant anemia in patients undergoing hemodialysis. However, a conclusion has not been reached concerning the prevalence and the effect of carnitine deficiency in patients undergoing peritoneal dialysis (PD). In this study, the prevalence of carnitine deficiency and the clinical factors associated with carnitine deficiency were investigated in 60 patients undergoing PD. The median age of the patients was 62.5 years (52.5–72.5 years), the proportion of male sex was 44/60 (73.3%), and the median PD period was 24 months (12–45 months). Carnitine deficiency (acyl carnitine/free carnitine ratio >0.4) was detected in 56/60 (93%) patients. Multiple regression analysis showed that the erythropoietin resistance index was independently associated with carnitine deficiency (β = 0.283, p = 0.04). These results suggest that carnitine plays pivotal roles in hematogenesis in patients undergoing PD.