Serum Hepcidin-25 and Risk of Mortality in Patients on Peritoneal Dialysis

Effects of Sodium-Glucose Cotransporter 2 Inhibitors in Diabetic and Non-Diabetic Patients with Advanced Chronic Kidney Disease in Peritoneal Dialysis on Residual Kidney Function: In Real-World Data

Background and Objectives: Peritoneal dialysis (PD) is a renal replacement therapy modality in which the dialysis dose can be individually adapted according to the patients' residual kidney function (RKF). RKF is a crucial factor for technique and patient survival. Pharmacological strategies aimed at slowing the loss of RKF in patients on PD are limited. Therefore, we aimed to assess the potential effects and safety of sodium-glucose cotransporter 2 (SGLT-2) inhibitors on the preservation of RKF in patients with and without type 2 diabetes mellitus (T2DM) on PD during an average follow-up of 6 months. Materials and Methods: In this retrospective observational, single-center study on real-world data, we included patients from the Peritoneal Dialysis Unit of the Hospital General Universitario de Ciudad Real, who started treatment with SGLT-2 inhibitors during the period from December 2022 to December 2023. Data on analytical and clinical parameters, RKF, and peritoneal membrane transport function were retrospectively collected at months 0, 3, and 6. Results: Out of 31 patients in our unit, 16 prevalent patients initiated treatment with SGLT-2 inhibitors (13 empagliflozin and 3 dapagliflozin). A total of 62.5% were male and the mean age was 67.3 years. The baseline peritoneal ultrafiltration was higher in the non-diabetic patient (NDMP) group than in the diabetic patient (DMP) group. However, the residual diuresis volume, 24 h residual renal clearance rate of urea in urine, and 24 h proteinuria were higher in the DMP group than in the NDMP group. At the sixth month, patients in both groups preserved RKF and diuresis, with a trend towards a non-significant reduction in proteinuria and blood pressure. Only two patients of the DMP group presented adverse effects. Conclusions: The use of SGLT-2 inhibitors in our sample of patients with and without T2DM on PD appears to be safe and effective to preserve RKF.

Serum fibroblast growth factor 23 concentration and the risk of mortality in patients undergoing peritoneal dialysis

BACKGROUND

Fibroblast growth factor 23 (FGF23) is a phosphate-regulating hormone that is secreted in large amounts early in chronic kidney disease. In this cohort, we aimed to investigate the association between serum FGF23 concentration and mortality in patients undergoing peritoneal dialysis (PD).

METHODS

Serum FGF23 level was determined by enzyme-linked immunosorbent assay (ELISA) in a large 15-year prospective cohort study of PD patients with stored serum samples at baseline. Kaplan-Meier survival curves and Cox proportional hazards models were performed to characterise the relationship of FGF23 with mortality.

RESULTS

A total of 737 incident PD patients were analysed. The baseline median FGF23 concentration was 683.2 (518.5-896.2) pg/mL. Age, serum phosphorus, high-density lipoprotein cholesterol and high-sensitivity C-reactive protein were independently correlated with serum FGF23 concentration. During a median follow-up of 66.7 (41.1-95.4) months, 171 of the 737 participants (23.2%) died, including 84 (49.1%) cardiovascular disease-related and 50 (29.2%) infection-related deaths. Multivariable Cox regression analysis showed that the adjusted hazard ratios of the highest tertile of serum FGF23 compared with those in the lowest tertile were 1.36 (95% confidence interval (CI): 0.89-2.07; p = 0.154), 0.75 (95% CI: 0.40-1.38; p = 0.353) and 2.66 (95% CI: 1.15-6.15; p = 0.022) for all-cause, cardiovascular disease-related and infection-related mortality, respectively.

CONCLUSION

High serum FGF23 concentration is associated with a higher risk of infection-related death for incident PD patients.

Neutrophil Percentage-to-Albumin Ratio and Risk of Mortality in Patients on Peritoneal Dialysis

Background

Neutrophil percentage-to-albumin ratio (NPAR), a new inflammatory marker, has been shown to be associated with poor prognosis in patients with cardiovascular disease. However, limited evidence is available for its role in peritoneal dialysis (PD) patients. Our study aimed at investigating the prognostic value of NPAR for mortality in PD patients.

Patients and Methods

This was a single center retrospective cohort study. A total of 1966 PD patients were enrolled in our study from January 2006 to December 2016 and were followed up until December 2021. Patients were stratified into tertiles according to baseline NPAR levels. The associations between NPAR levels with all-cause and cardiovascular mortality were estimated using Cox proportional hazards models. Receiver operating characteristic (ROC) analysis was performed to compare the mortality predictive values of NPAR and other known biomarkers, such as NLR (neutrophil-to-lymphocyte ratio), PLR (platelet-to-lymphocyte ratio), LHR (low-density lipoprotein cholesterol-to-high-density lipoprotein cholesterol ratio) and MLR (monocyte-to-lymphocyte ratio).

Results

During a median follow-up of 48.1 months, 503 (25.6%) patients died, in which cardiovascular disease (CVD) death dominated 50.3%. Multivariate Cox regression analysis revealed that the highest NPAR tertile was significantly associated with a higher risk of all-cause and cardiovascular mortality (HR 1.51, 95% CI 1.14-1.98; HR 1.57, 95% CI 1.07-2.31; respectively) compared with tertile 1. The AUC values of NPAR were 0.62 (95% CI 0.60-0.65, P < 0.001) for all-cause mortality and 0.61 (95% CI 0.57-0.65, P < 0.001) for cardiovascular mortality.

Conclusion

Our study showed that higher NPAR levels were independently associated with increased risk of all-cause and cardiovascular mortality in PD patients. Notably, our results demonstrated that NPAR exhibited superior predictive value for mortality compared to NLR, PLR, MLR, and LHR.

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.

Association between Iron Status and Survival in Patients on Chronic Hemodialysis

The aim of this study was to evaluate survival rates according to iron status in patients undergoing maintenance hemodialysis (HD). Thus, the National HD Quality Assessment Program dataset and claims data were used for analysis (n = 42,390). The patients were divided into four groups according to their transferrin saturation rate and serum ferritin levels: Group 1 (n = 34,539, normal iron status); Group 2 (n = 4476, absolute iron deficiency); Group 3 (n = 1719, functional iron deficiency); Group 4 (n = 1656, high iron status). Using univariate and multivariable analyses, Group 1 outperformed the three other groups in terms of patient survival. Using univariate analysis, although Group 2 showed a favorable trend in patient survival rates compared with Groups 3 and 4, the statistical significance was weak. Group 3 exhibited similar patient survival rates to Group 4. Using multivariable Cox regression analysis, Group 2 had similar patient survival rates to Group 3. Subgroup analyses according to sex, diabetic status, hemoglobin level ≥ 10 g/dL, and serum albumin levels ≥ 3.5 g/dL indicated similar trends to those of the total cohort. However, subgroup analysis based on patients with a hemoglobin level < 10 g/dL or serum albumin levels < 3.5 g/dL showed a weak statistical significant difference compared with those with hemoglobin level ≥ 10 g/dL, or serum albumin levels ≥ 3.5 g/dL. In addition, the survival difference between Group 4 and other groups was greater in old patients than in young ones. Patients with a normal iron status had the highest survival rates. Patient survival rates were similar or differed only modestly among the groups with abnormal iron status. In addition, most subgroup analyses revealed similar trends to those according to the total cohort. However, subgroup analyses based on age, hemoglobin, or serum albumin levels showed different trends.

The rationale for the need to study sodium-glucose co-transport 2 inhibitor usage in peritoneal dialysis patients

The wave of kidney and heart outcome trials, showing multiple potential benefits for sodium-glucose co-transport 2 (SGLT2) inhibitors, have excluded patients with an estimated glomerular filtration rate below 25 ml/min/1.73 m2. However, dialysis patients are at the highest risk of cardiovascular disease and would benefit most from effective cardioprotective therapies. There is emerging evidence from experimental studies and post hoc analyses of randomised clinical trials that SGLT2 inhibitors are well tolerated and may also be effective in preventing cardiovascular and mortality outcomes in patients with severe chronic kidney disease, including patients receiving dialysis. As such, extending the usage of SGLT2 inhibitors to dialysis patients could provide a major advancement in their care. Peritoneal dialysis (PD) patients have an additional unmet need for effective pharmacotherapy to preserve their residual kidney function (RKF), with its associated mortality benefits, and for treatment options that help reduce the risk of transfer to haemodialysis. Experimental data suggest that SGLT2 inhibitors, via various mechanisms, may preserve RKF and protect the peritoneal membrane. There is sound physiological rationale and an urgent clinical need to execute robust randomised control trials to study the use of SGLT2 inhibitors in PD patients to answer important questions of relevance to patients and healthcare systems.