On the importance of the interplay of residual renal function with clinical outcomes in end-stage kidney disease

Intra-abdominal pressure and residual renal function decline in peritoneal dialysis: a threshold-based investigation

BACKGROUND

The potential impact of elevated intra-abdominal pressure (IAP) on residual renal function (RRF) has not been determined. The objective of this study was to investigate the relationship between IAP and the rate of RRF decline in newly initiated peritoneal dialysis (PD) patients, and to identify the optimal IAP threshold value for delaying the deterioration of RRF.

METHODS

A cohort of 62 newly initiated PD patients who completed both 6- and 12-month follow-up evaluations was obtained using the Durand method. A logistic regression model was used to identify variables associated with a rapid decline in RRF. Receiver operating characteristic (ROC) curves were generated to determine the optimal threshold value. Another retrospective cohort analysis was performed to validate the identified critical value.

RESULTS

For each 1 cmH2O increase in IAP, the risk of a rapid decline in the RRF increased by a factor of 1.679. Subsequent analysis revealed that patients in the high IAP group had more significant decreases in residual renal estimated glomerular filtration rate (eGFR) (Z = -3.694, p < 0.001) and urine volume (Z = -3.121, p < 0.001) than did those in the non-high IAP group. Furthermore, an IAP ≥15.65 cmH2O was a robust discriminator for the prediction of the rate of RRF decline.

CONCLUSION

Patients in the high IAP group experienced a more rapid decline in RRF. Additionally, an optimal critical pressure of 15.65 cmH2O was identified for predicting the rate of RRF decline. IAP, as one of the factors contributing to the rapid decline in RRF in the first year of PD, should be given due attention.

Selection of dialysis methods for end-stage kidney disease patients with diabetes

The increasing prevalence of diabetes has led to a growing population of end-stage kidney disease (ESKD) patients with diabetes. Currently, kidney transplantation is the best treatment option for ESKD patients; however, it is limited by the lack of donors. Therefore, dialysis has become the standard treatment for ESKD patients. However, the optimal dialysis method for diabetic ESKD patients remains controversial. ESKD patients with diabetes often present with complex conditions and numerous complications. Furthermore, these patients face a high risk of infection and technical failure, are more susceptible to malnutrition, have difficulty establishing vascular access, and experience more frequent blood sugar fluctuations than the general population. Therefore, this article reviews nine critical aspects: Survival rate, glucose metabolism disorder, infectious complications, cardiovascular events, residual renal function, quality of life, economic benefits, malnutrition, and volume load. This study aims to assist clinicians in selecting individualized treatment methods by comparing the advantages and disadvantages of hemodialysis and peritoneal dialysis, thereby improving patients' quality of life and survival rates.

Shared decision making in elderly patients with kidney failure

'Elderly' is most commonly defined as an individual aged 65 years or older. However, this definition fails to account for the differences in genetics, lifestyle and overall health that contribute to significant heterogeneity among the elderly beyond chronological age. As the world population continues to age, the prevalence of chronic diseases, including chronic kidney disease (CKD), is increasing and CKD frequently progresses to kidney failure. Moreover, frailty represents a multidimensional clinical entity highly prevalent in this population, which needs to be adequately assessed to inform and support medical decisions. Selecting the optimal treatment pathway for the elderly and frail kidney failure population, be it haemodialysis, peritoneal dialysis or conservative kidney management, is complex because of the presence of comorbidities associated with low survival rates and impaired quality of life. Management of these patients should involve a multidisciplinary approach including doctors from various specialties, nurses, psychologists, dieticians and physiotherapists. Studies are mostly retrospective and observational, lacking adjustment for confounders or addressing selection and indication biases, making it difficult to use these data to guide treatment decisions. Throughout this review we discuss the difficulty of making a one-size-fits-all recommendation for the clinical needs of older patients with kidney failure. We advocate that a research agenda for optimization of the critical issues we present in this review be implemented. We recommend prospective studies that address these issues, and systematic reviews incorporating the complementary evidence of both observational and interventional studies. Furthermore, we strongly support a shared decision-making process matching evidence with patient preferences to ensure that individualized choices are made regarding dialysis vs conservative kidney management, dialysis modality and optimal vascular access.

Early aging and premature vascular aging in chronic kidney disease

Aging is the progressive decline of body functions and a number of chronic conditions can lead to premature aging characterized by frailty, a diseased vasculature, osteoporosis, and muscle wasting. One of the major conditions associated with premature and accelerated aging is chronic kidney disease (CKD), which can also result in early vascular aging and the stiffening of the arteries. Premature vascular aging in CKD patients has been considered as a marker of prognosis of mortality and cardiovascular morbidity and therefore requires further attention. Oxidative stress, inflammation, advanced glycation end products, fructose, and an aberrant gut microbiota can contribute to the development of early aging in CKD patients. There are several key molecular pathways and molecules which play a role in aging and vascular aging including nuclear factor erythroid 2-related factor 2 (Nrf-2), AMP-activated protein kinase (AMPK), sirtuin 1 (SIRT1), and klotho. Potential therapeutic strategies can target these pathways. Future studies are needed to better understand the importance of premature aging and early vascular aging and to develop therapeutic alternatives for these conditions.

A new immune disease: systemic hypertension

Systemic hypertension is the most common medical comorbidity affecting the adult population globally, with multiple associated outcomes including cerebrovascular diseases, cardiovascular diseases, vascular calcification, chronic kidney disease, metabolic syndrome and mortality. Despite advancements in the therapeutic field approximately one in every five adult patients with hypertension is classified as having treatment-resistant hypertension, indicating the need for studies to provide better understanding of the underlying pathophysiology and the need for more therapeutic targets. Recent pre-clinical studies have demonstrated the role of the innate and adaptive immune system including various cell types and cytokines in the pathophysiology of hypertension. Moreover, pre-clinical studies have indicated the potential beneficial effects of immunosuppressant medications in the control of hypertension. Nevertheless, it is unclear whether such pathophysiological mechanisms and therapeutic alternatives are applicable to human subjects, while this area of research is undoubtedly a rapidly growing field.

Dialysis after kidney transplant failure: how to deal with this daunting task?

The best treatment for patients with end-stage kidney disease is kidney transplantation, which, if successful provides both a reduction in mortality and a better quality of life compared to dialysis. Although there has been significant improvement in short-term outcomes after kidney transplantation, long-term graft survival still remains insufficient. As a result, there has been an increase in the number of individuals who need dialysis again after kidney transplant failure, and increasingly contribute to kidney transplant waiting lists. Starting dialysis after graft failure is a difficult task not only for the patients, but also for the nephrologists and the care team. Furthermore, recommendations for management of dialysis after kidney graft loss are lacking. Aim of this narrative review is to provide a perspective on the role of dialysis in the management of patients with failed kidney allograft. Although numerous studies have reported higher mortality in patients undergoing dialysis following kidney allograft failure, reports are contrasting. A patient-centered, individualized approach should drive the choices of initiating dialysis, dialysis modality, maintenance of immunosuppressive drugs and vascular access.

Gut Microbiota Interventions to Retain Residual Kidney Function

Residual kidney function for patients with chronic kidney disease (CKD) is associated with better quality of life and outcome; thus, strategies should be implemented to preserve kidney function. Among the multiple causes that promote kidney damage, gut dysbiosis due to increased uremic toxin production and endotoxemia need attention. Several strategies have been proposed to modulate the gut microbiota in these patients, and diet has gained increasing attention in recent years since it is the primary driver of gut dysbiosis. In addition, medications and faecal transplantation may be valid strategies. Modifying gut microbiota composition may mitigate chronic kidney damage and preserve residual kidney function. Although various studies have shown the influential role of diet in modulating gut microbiota composition, the effects of this modulation on residual kidney function remain limited. This review discusses the role of gut microbiota metabolism on residual kidney function and vice versa and how we could preserve the residual kidney function by modulating the gut microbiota balance.

Phosphate Control in Peritoneal Dialysis Patients: Issues, Solutions, and Open Questions

Hyperphosphatemia is a common complication in advanced chronic kidney disease and contributes to cardiovascular morbidity and mortality. The present narrative review focuses on the management of phosphatemia in uremic patients receiving peritoneal dialysis. These patients frequently develop hyperphosphatemia since phosphate anion behaves as a middle-size molecule despite its low molecular weight. Accordingly, patient transporter characteristics and peritoneal dialysis modalities and prescriptions remarkably influence serum phosphate control. Given that phosphate peritoneal removal is often insufficient, especially in lower transporters, patients are often prescribed phosphate binders whose use in peritoneal dialysis is primarily based on clinical trials conducted in hemodialysis because very few studies have been performed solely in peritoneal dialysis populations. A crucial role in phosphate control among peritoneal dialysis patients is played by diet, which must help in reducing phosphorous intake while preventing malnutrition. Moreover, residual renal function, which is preserved in most peritoneal dialysis patients, significantly contributes to maintaining phosphate balance. The inadequate serum phosphate control observed in many patients on peritoneal dialysis highlights the need for large and well-designed clinical trials including exclusively peritoneal dialysis patients to evaluate the effects of a multiple therapeutic approach on serum phosphate control and on hard clinical outcomes in this high-risk population.

Iron status and anemia control are related to peritoneal membrane properties in peritoneally dialyzed patients

Background

Characteristics of peritoneal membrane is unique and individually different in peritoneal dialysis patients. Relationship between specific nature of peritoneal transport, anemia and inflammation has not yet been extensively studied. We attempted to outline the complex interplay of several biomarkers of iron status and their association with peritoneal transport, degree of inflammation and residual renal function.

Methods

A total of 58 patients treated with peritoneal dialysis either CAPD or APD for at least 3 months were enrolled in this study. Full blood count, traditional markers of iron status (transferrin saturation-TSAT and ferritin), serum erythroferrone-ERFE, soluble transferrin receptor (sTfR), hepcidin, zonulin, growth differentiation factor -15 (GDF15), IL-16, hsCRP and hypoxia-inducible factor-α (HIF-1-α; in serum and dialysate) were measured using commercially available tests. We also performed Peritoneal Equilibrium Test and assessed GFR level.

Results

Hb levels above 10 g/dL was found in 74% of patients. Hb levels positively correlated with residual renal function and nutritional status. Adequate iron status was diagnosed in 69% of subjects, only in 9% of patients, criteria for absolute iron deficiency were met. Serum ERFE correlated inversely with hepcidin levels but was not associated with erythropoietin stimulating agent dose. Peritoneal transport had strong correlation with dialysate sTfR (p < 0.05), dialysate hepcidin (p < 0.05), dialysate GDF15 (p < 0.01) and dialysate zonulin (p < 0.001) levels, as well as serum IL6 (p = 0.03), serum hs-CRP (p = 0.04) and dialysate hs-CRP (p = 0.04).

Conclusion

Residual kidney function contributes considerably to better control of anemia. Various degree of inflammation is inherent to PD patients. Additionally, fast-average peritoneal transport is associated with greater degree of inflammation and higher concentration of markers of iron status, GDF15 and zonulin in dialysate. This finding may indicate more effective clearance of higher-range middle molecules in fast-average transporters. The role of ERFE as a marker of erythropoiesis in PD patients requires further investigation.

Dialysis in Pregnancy: An Update Review

Chronic kidney disease and end-stage kidney disease (ESKD) are important public health problems with increased rates of morbidity, mortality, and social costs. Pregnancy is rare in patients with ESKD, with reduced fertility rates in women undergoing dialysis. Although current advances have led to an increase in live births in pregnant dialysis patients, this modality still has an increased risk of multiple adverse events in pregnant women. Despite these existing risks, large-scale studies investigating the management of pregnant women on dialysis are lacking, resulting in the absence of consensus guidelines for this patient group. In this review, we aimed to present the effects of dialysis during pregnancy. We first discuss pregnancy outcomes in dialysis patients and the development of acute kidney injury during pregnancy. Then, we discuss our recommendations for the management of pregnant dialysis patients, including the maintenance of pre-dialysis blood urea nitrogen levels, the ideal frequency and duration of hemodialysis sessions, as well as the modality of renal replacement therapies, the difficulty of maintaining peritoneal dialysis in the third trimester of pregnancy, and optimization of prepregnancy modifiable risk factors. Finally, we present our recommendations for future studies investigating dialysis among pregnant patients.

Durable Anti-SARS-CoV-2 Antibody Response after mRNA-1273 Booster in Peritoneal Dialysis Patients during the Omicron Wave

Anti-SARS-CoV-2 vaccination of dialysis patients has been proven to be safe and effective to reduce COVID-19-related morbidity and mortality. However, data on the durability of anti-SARS-CoV-2 antibodies post-vaccination in peritoneal dialysis (PD) patients are scarce. In this prospective single-center cohort study we measured anti-SARS-CoV-2 RBD antibodies 3 and 6 months after the 3rd dose of the mRNA-1273 vaccine in 27 adult PD patients and recorded breakthrough infections. Furthermore, in a mixed model analysis, we analyzed potential factors influencing the humoral response following vaccination. Anti-SARS-CoV-2 RBD antibody levels declined from 21,424 BAU/mL at 1 month to 8397 BAU/mL at 3 months and to 5120 BAU/mL at 6 months after the 3rd dose, but remained higher than pre-3rd dose levels (212 BAU/mL). Eight patients (29.6%) were infected with SARS-CoV-2 within six months from the 3rd dose during the Omicron wave. Previous high antibody levels, high glomerular filtration rate (GFR) and low Davies Comorbidity Score were associated with higher anti-SARS-CoV-2 antibody levels after the booster. In conclusion, PD patients exhibited a robust and durable humoral response after a third dose of the mRNA-1273 vaccine. A high GFR and low comorbidity as well as previous high antibody levels predicted a better humoral response to vaccination.