Peritoneal transport status and first episode of peritonitis: a large cohort study

Association between serum total indoxyl sulfate, intraperitoneal inflammation, and peritoneal dialysis technique failure: a 3-year prospective cohort study

BACKGROUND

The impact of protein-bound uremic toxins, specifically indoxyl sulfate (IS) on peritoneal dialysis (PD) complications remains controversial. This study aimed to explore the link between serum total IS (tIS) levels, proinflammatory cytokines in serum and peritoneal dialysis effluent (PDE), and PD technique survival.

METHODS

In this prospective cohort study, 84 patients were followed up for three years and analyzed. Stratification into low-tIS (< 22.6 µmol/L) and high-tIS (≥ 22.6 µmol/L) groups was based on the median serum tIS concentration. Logistic regression, Kaplan-Meier, receiving operation characteristic, and Cox regression analyses assessed associations between tIS levels, cytokine concentrations (IL-6, MCP-1, TNF-α), and PD technique failure.

RESULTS

Patients in the high-tIS group were older and had a higher prevalence of diabetes, a greater incidence of PD-related peritonitis, elevated diastolic blood pressure, and lower HDL cholesterol compared to those in the low-tIS group. They also exhibited higher peritoneal transport characteristics, lower dialysis adequacy, and reduced peritoneal creatinine clearance. Elevated tIS levels significantly correlated with higher PDE cytokine levels, without a corresponding rise in serum cytokine levels. Serum tIS levels ≥ 50 µmol/L predicted PD technique failure with 70.4% sensitivity and 87.9% specificity (p < 0.0001). The association between high tIS levels and PD technique failure remained significant after adjusting for confounders identified in logistic regression, including peritoneal weekly creatinine clearance, the D/P creatinine ratio, high peritoneal transport status, and PDE IL-6 and MCP-1 concentrations (HR 2.9, 95% CI 1.13; 8.21).

CONCLUSION

Our findings are the first to demonstrate a link between elevated tIS levels, peritoneal inflammation, and an increased risk of PD technique failure. Monitoring tIS levels in PD patients could be clinically relevant for risk assessment and personalized management, potentially improving long-term PD outcomes. Future research should explore interventions targeting tIS reduction to alleviate peritoneal inflammation and improve PD prognosis.

Peritoneal dialysis-related infections in elderly patients

This review outlines the epidemiology, characteristics, risk factors, and prognosis of peritoneal dialysis (PD)-related peritonitis, PD catheter-related infections, and the effects of assisted PD in elderly patients from the Japanese perspective. Based on the literature, the incidence of peritonitis is likely to be higher in elderly patients than in younger patients. The most frequent causative bacteria in elderly patients are Gram-positive bacteria, as in adult PD patients, most commonly due to transcatheter infection. However, elderly patients may have difficulty recognizing cloudy drainage fluid due to decreased visual acuity. Hypokalemia, the use of gastric acid suppressants, prophylactic antibiotic use before endoscopy, biocompatible fluids and hypoalbuminemia considered modifiable risk factors for peritonitis. However, the mechanism by which treatment of hypokalemia prevents peritonitis is unknown. Currently, the relationship between gastric acid suppression therapy and peritonitis in elderly patients is debatable, with no evidence to strongly recommend uniform discontinuation of gastric acid suppression therapy. Exit-site infection (ESI) is a major risk factor for the development of peritonitis, and appropriate prevention and management of ESI may reduce infection-related hospitalizations in PD patients. Currently, no randomized, controlled trials have verified the effectiveness of antibiotic application for ESI in Japan, but results from other countries are awaited. In assisted PD, it is extremely important that family members, caregivers, and nurses who support the procedure receive sufficient education and training from medical professionals familiar with PD. Early detection and treatment of PD-related infections are required because the risk of death increases in elderly patients.

Analysis of risk factors for refractory peritonitis in patients undergoing peritoneal dialysis

OBJECTIVE

To explore the risk factors for refractory peritonitis in patients undergoing peritoneal dialysis.

METHODS

We retrospectively collected data from 130 patients who underwent peritoneal dialysis (PD) and received peritonitis treatment at the Renal Disease Center of Beijing Luhe Hospital affiliated with Capital Medical University from January 1, 2016 to January 30, 2023. According to clinical treatment results, patients with refractory peritonitis were classified as the refractory group (n=52 cases), and those with non-refractory peritonitis were classified as the non-refractory group (n=78 cases). Baseline information and laboratory indicators of patients in each group were collected, and Logistic regression model was used to identify the risk factors for the poor prognosis of peritonitis patients.

RESULTS

There were statistically significant differences in dialysis time, dialysate sugar concentration and inducement type between the refractory group and the non-refractory group (P<0.05). The values of peripheral white blood cells (pWBC), T helper 2 cell (Th2), T regulatory cell (Treg), Treg/Th17 and C-reactive protein (CRP) in the refractory group were significantly higher than those in the non-refractory group, while the values of T helper 17 cell (Th17) and albumin (ALB) were significantly lower (all P<0.05). There were no significant differences in serum creatinine, blood urea, Th1, hemoglobin (Hb) and blood calcium levels between the two groups (all P>0.05). Gram-positive bacteria were the main pathogenic bacteria of peritonitis in all groups. The proportion of enterococcus/streptococcal peritonitis in the refractory group was higher than that in the non-refractory group (P<0.05). Logistic regression identified elevated pWBC, higher dialysate sugar concentration, exit-site infection and gram-negative bacteria infection as independent risk factors for refractory peritonitis in patients undergoing PD (all P<0.05).

CONCLUSION

Elevated pWBC, high glucose dialysate concentration, exit-site infection, and gram-negative bacteria infection are risk factors for refractory peritonitis in patients undergoing PD.

Albumin-to-alkaline phosphatase ratio as a novel prognostic indicator in patients undergoing peritoneal dialysis: a propensity score matching analysis

Background

Though the albumin-to-alkaline phosphatase ratio (AAPR) is used as a biomarker in various diseases, little is known about its effect on outcomes after peritoneal dialysis (PD).

Methods

This multicenter retrospective study comprised 357 incident PD patients stratified according to the AAPR. Propensity score matching (PSM) was performed to identify 85 patients for a well-matched comparison of all-cause and cardiovascular mortality. Using Cox regression, we performed univariate and multivariate analyses to investigate the prognostic value of the AAPR and established a Kaplan-Meier curve-predicted nomogram to estimate expected overall survival (OS). We assessed the predictive accuracy using the concordance index (c-index).

Results

We found that the optimal cut-off of the AAPR to predict mortality was 0.36. In the present cohort of patients undergoing PD, a low AAPR strongly correlated with worse OS. In the multivariate analysis, the AAPR was shown to be an independent marker predicting reduced OS both before [hazard ratio (HR) 1.68, 95% confidence interval (CI) 1.08-2.60, P = 0.020] and after PSM (HR 1.96, 95% CI 1.06-3.62, P = 0.020). We also observed significant differences in OS in several subgroups, but not the group of patients with comorbidities. A nomogram was established to predict overall survival, with a c-index for prediction accuracy was 0.71 after PSM.

Conclusion

AAPR has potential as an independent prognostic biomarker in patients undergoing PD.

The centre-calculated cutoff value is better for identifying fast peritoneal solute transfer of patients on peritoneal dialysis than the traditional value: a retrospective cohort study

Background

The mean 4-h dialysate to plasma ratio of creatinine (4-h D/Pcr) is a vital cutoff value for recognizing the fast peritoneal solute transfer rate (PSTR) in patients on peritoneal dialysis (PD); however, it shows a noticeable centre effect. We aimed to investigate our centre-calculated cutoff value (CCV) of 4-h D/Pcr and compare it with the traditional cutoff value (TCV) (0.65).

Methods

In this study, we enrolled incident PD patients at our centre from 2008 to 2019, and divided them into fast or non-fast PSTR groups according to baseline 4-h D/Pcr-based CCV or TCV. We compared the efficiency of the fast PSTR recognized by two cutoff values in predicting mortality, ultrafiltration (UF) insufficiency and technical survival.

Results

In total, 1905 patients were enrolled, with a mean 4-h D/Pcr of 0.71 ± 0.11. Compared with TCV (0.65), CCV (0.71) showed superiority in predicting mortality of PD patients [hazard ratio (HR) 1.27, 95% confidence interval (CI) 1.02-1.59 vs HR 1.24, 95% CI 0.97-1.59]. The odds ratio (OR) of the fast PSTR in centre classification was slightly higher than traditional classification in predicting UF insufficiency (OR 1.67, 95% CI 1.25-2.24 vs OR 1.60, 95% CI 1.15-2.22). Additionally, the restricted cubic splines 4-h D/Pcr has an S-shaped association with mortality and UF insufficiency, and the inflection points of 4-h D/Pcr were 0.71 (equal to CCV).

Conclusions

The CCV of 4-h D/Pcr for identifying fast PSTR was 0.71. It was superior to TCV in predicting mortality and UF insufficiency.

Multidrug-resistant organism-peritoneal dialysis associated peritonitis: clinical and microbiological features and risk factors of treatment failure

Background

Multidrug-resistant (MDR) bacterial infection causes difficulty in the therapy of peritoneal dialysis-associated peritonitis (PDAP); however, there are few studies on multidrug-resistant organism (MDRO)-PDAP. In view of growing concerns about MDRO-PDAP, the aim of this study was to investigate the clinical features, risk factors of treatment failure, and causative pathogens of MDRO-PDAP.

Methods

In total, 318 patients who underwent PD between 2013 and 2019 were included in this multicenter retrospective study. Clinical features, patient outcomes, factors related to treatment failure, and microbiological profiles associated with MDRO-PDAP were analyzed and risk factors for treatment failure associated with MDR-Escherichia coli (E. coli) were further discussed.

Results

Of 1,155 peritonitis episodes, 146 eligible episodes of MDRO-PDAP, which occurred in 87 patients, were screened. There was no significant difference in the composition ratio of MDRO-PDAP between 2013-2016 and 2017-2019 (p > 0.05). E. coli was the most prevalent MDRO-PDAP isolate, with high sensitivity to meropenem (96.0%) and piperacillin/tazobactam (89.1%). Staphylococcus aureus was the second most common isolate and was susceptible to vancomycin (100%) and linezolid (100%). Compared to non-multidrug-resistant organism-PDAP, MDRO-PDAP was associated with a lower cure rate (66.4% vs. 85.5%), higher relapse rate (16.4% vs. 8.0%), and higher treatment failure rate (17.1% vs.6.5%). Dialysis age [odds ratio (OR): 1.034, 95% confidence interval (CI): 1.016-1.052, p < 0.001] and >2 previous peritonitis episodes (OR: 3.400, 95% CI: 1.014-11.400, p = 0.047) were independently associated with treatment failure. Furthermore, longer dialysis age (OR: 1.033, 95% CI: 1.003-1.064, p = 0.031) and lower blood albumin level (OR: 0.834, 95% CI: 0.700-0.993, p = 0.041) increased the risk of therapeutic failure for MDR-E. coli infection.

Conclusion

The proportion of MDRO-PDAP has remained high in recent years. MDRO infection is more likely to result in worse outcomes. Dialysis age and previous multiple peritonitis infections were significantly associated with treatment failure. Treatment should be promptly individualized based on local empirical antibiotic and drug sensitivity analyses.

A retrospective study of baseline peritoneal transport character and left ventricular hypertrophy in incident peritoneal dialysis patients: interrelationship and prognostic impacts

BACKGROUND

Left ventricular hypertrophy is associated with adverse outcomes among peritoneal dialysis patients. The aim of this study was to evaluate the prognostic impact of baseline left ventricular hypertrophy and its relationship with baseline peritoneal transfer characteristics in peritoneal dialysis patients.

METHODS

We enrolled 151 incident peritoneal dialysis patients to perform a multicentric retrospective cohort study since January 1, 2017 to January 31, 2021. Patients were grouped based on baseline dialysate-to-plasma creatinine ratio at 4 h as follows: low (<0.50), low average (0.5-0.64), high average (0.65-0.80) and high (≥0.81). Echocardiography and clinic data were recorded yearly. The Cox proportional hazards models and competing risk model were used to evaluate patients' survival. Generalized linear mixed models were performed to explore risk factors associated with left ventricular hypertrophy.

RESULTS

During a median follow-up period of 33 months (range, 16-48 months), 21 (13.9%) patients died, including 16 (10.60%) cardiovascular deaths. Controlling the competing risks of switching to hemodialysis, kidney transplantation and loss to follow-up, baseline left ventricular hypertrophy was an independent risk factor for all-cause mortality (subdistribution hazard ratio, 2.645; 95% confidence interval, 1.156-6.056; p = 0.021). Baseline high and high average transport status were positively related to left ventricular mass index and left atrium diameter 2 years after PD initiation.

CONCLUSION

Baseline fast peritoneal solute transport rate may be an effect factor for aggravating left ventricular hypertrophy which predicted poor outcomes for peritoneal dialysis patients. The findings offered important ideas for further prospective intervention study.

Glycoprotein 96 in Peritoneal Dialysis Effluent-Derived Extracellular Vesicles: A Tool for Evaluating Peritoneal Transport Properties and Inflammatory Status

Background

Extracellular vesicles (EVs) from peritoneal dialysis effluent (PDE), containing molecules such as proteins and microRNAs (miRNAs), may be potential biological markers to monitor peritoneal function or injury. Peritoneal inflammation is an important determinant of peritoneal solute transport rate (PSTR). Thus, the aim of this study is to determine whether the specific proteins capable of evaluating the PSTR could be found in PDE-EVs, and explore the underlying mechanism for the association between PSTR and peritoneal inflammation.

Methods

Sixty patients undergoing peritoneal dialysis (PD) were divided into two groups: high/high average transport (H/A) group (PET >0.65) and low/low average transport (L/A) group (PET <0.65). EVs derived from PDE (PDE-EVs) were isolated by ultracentrifugation. Proteomic analysis was performed to explore the differentially expressed proteins and identify the potential biomarkers in PDE-EVs from the two groups, and we focused on glycoprotein 96 (GP96) as it could be involved in the inflammatory process. The expression of GP96 in PDE-EVs and inflammatory cytokines was quantified by real-time PCR and enzyme-linked immunosorbent assay. The infiltration of macrophages and neutrophils into the peritoneum was detected using immunohistochemistry in a PD rat model.

Results

The expression of PDE-EVs-GP96 was significantly higher in the H/A group, and was positively correlated with the PSTR and the level of the inflammatory factor interleukin (IL)-6. GP96-enriched EVs enhanced the secretion of proinflammatory cytokines IL-1β, IL-6, tumor necrosis factor (TNF)-α, and IL-8 in macrophages, which was reversed by a pharmacological GP96-specific inhibitor (PU-WS13). The GP96 inhibitor also reduced local peritoneal inflammation by decreasing the infiltration of inflammatory cells and levels of proinflammatory cytokines (IL-6 and TNF-α) and chemokines (CCL2, CXCL1, and CXCL2) in a PD rat model.

Conclusions

PDE-EVs-GP96 is a new promising tool to evaluate the status of peritoneal inflammation and PSTR, and the mechanism may be related to affecting the inflammatory properties of macrophages.