Longitudinal association between dietary protein intake and survival in peritoneal dialysis patients

BACKGROUND

Decreased dietary protein intake (DPI) may lead to protein-energy malnutrition and may be associated with increased mortality risk. We hypothesized that longitudinal changes in dietary protein intake have independent associations with survival in peritoneal dialysis (PD) patients.

METHODS

668 stable PD patients were selected in the study from January 2006 to January 2018 and were followed up until December 2019. Their three-day dietary records were collected at the baseline (the sixth month after PD) and thereafter every 3 months for two and a half years. The latent class mixed models (LCMM) were used to identify subgroups of PD patients with similar longitudinal trajectories of DPI. The relation between DPI (baseline and longitudinal data) and survival was examined using Cox model to estimate death hazard ratios. Meanwhile, different formulae were used to assess nitrogen balance.

RESULTS

The results showed that baseline DPI ≤ 0.60g/kg/day was associated with the worst outcome in PD patients. Patients with DPI 0.80-0.99g/kg/day and DPI ≥ 1.0g/kg/day both presented positive nitrogen balance; patients with DPI 0.61-0.79g/kg/day presented obviously negative nitrogen balance. Longitudinal association between time-dependent DPI and survival was found in PD patients. The consistently low DPI' (0.61-0.79g/kg/d) group was correlated with increased death risk as compared with the 'consistently median DPI' group (0.80-0.99g/kg/d, HR = 1.59, p = 0.008), whereas there was no difference in survival between 'consistently median DPI' group and 'high-level DPI' group (≥1.0 g/kg/d, p > 0.05).

CONCLUSION

Our study revealed that DPI ≥ 0.8 g/kg/day was beneficial to the long-term outcome for the PD population.

A modified renal risk score for Chinese patients with antineutrophil cytoplasmic antibody-associated vasculitis

BACKGROUND

The renal risk score (RRS) is a useful tool to predict end-stage renal disease (ESRD) in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The current study aimed to validate the predictive performance of RRS and to further modify this model in Chinese AAV patients.

METHODS

Two hundred and seventy-two patients diagnosed with AAV confirmed by renal biopsies were retrospectively enrolled from a single center. The RRS was calculated based on 3 categorical variables, i.e., the proportion of normal glomeruli, the proportion of interstitial fibrosis and tubular atrophy (IF/TA), and eGFR at biopsy, classifying these patients into low-, medium-, and high-risk groups. In addition, a modified model was developed based on the RRS and was further validated in another independent cohort of 117 AAV patients. The predictive performance of each model was evaluated according to discrimination and calibration.

RESULTS

Patients were classified by the RRS into low- (26.5%), medium- (46.7%), and high-risk (26.8%) groups, with 120-month renal survival rates of 93.3%, 57.2%, and 18.4%, respectively (P < 0.001). The RRS showed good discrimination but less satisfactory calibration. Therefore, a modified model with improved discrimination and calibration was developed in Chinese AAV patients, with eGFR, proportion of normal glomeruli (both as continuous variables), and IF/TA (< 25%, 25-50%, > 50%) included. Internal and external validation of the modified model were performed. Finally, an online risk prediction tool was developed based on the modified model.

CONCLUSIONS

The RRS was an independent predictor of ESRD of AAV patients. The modified model could predict the probability of ESRD for AAV patients with improved performance in Chinese AAV patients.

5-Hydroxymethylcytosine profiles in plasma cell-free DNA reflect molecular characteristics of diabetic kidney disease

BACKGROUND

Diabetic kidney disease (DKD), one of the main complications of diabetes mellitus (DM), has become a frequent cause of end-stage renal disease. A clinically convenient, non-invasive approach for monitoring the development of DKD would benefit the overall life quality of patients with DM and contribute to lower medical burdens through promoting preventive interventions.

METHODS

We utilized 5hmC-Seal to profile genome-wide 5-hydroxymethylcytosines in plasma cell-free DNA (cfDNA). Candidate genes were identified by intersecting the differentially hydroxymethylated genes and differentially expressed genes from the GSE30528 and GSE30529. Then, a protein interaction network was constructed for the candidate genes, and the hub genes were identified by the MCODE and cytoHubba algorithm. The correlation analysis between the hydroxymethylation level of the hub genes and estimated glomerular filtration rate (eGFR) was carried out. Finally, we demonstrated differences in expression levels of the protein was verified by constructing a mouse model of DKD. In addition, we constructed a network of interactions between drugs and hub genes using the Comparative Toxicogenomics Database.

RESULTS

This study found that there were significant differences in the overall distribution of 5hmC in plasma of patients with DKD, and an alteration of hydroxymethylation levels in genomic regions involved in inflammatory pathways which participate in the immune response. The final 5 hub genes, including (CTNNB1, MYD88, CD28, VCAM1, CD44) were confirmed. Further analysis indicated that this 5-gene signature showed a good capacity to distinguish between DKD and DM, and was found that protein levels were increased in renal tissue of DKD mice. Correlation analysis indicated that the hydroxymethylation level of 5 hub genes were nagatively correlated with eGFR. Toxicogenomics analysis showed that a variety of drugs for the treatment of DKD can reduce the expression levels of 4 hub genes (CD44, MYD88, VCAM1, CTNNB1).

CONCLUSIONS

The 5hmC-Seal assay was successfully applied to the plasma cfDNA samples from a cohort of DM patients with or without DKD. Altered 5hmC signatures indicate that 5hmC-Seal has the potential to be a non-invasive epigenetic tool for monitoring the development of DKD and it provides new insight for the future molecularly targeted anti-inflammation therapeutic strategies of DKD.

The history of peritoneal dialysis in China: past, present and future trends

Peritoneal dialysis (PD) was introduced in China more than 60 years ago and has grown continuously since then. Now China leads the first of the world in number of patients on PD. In this manuscript a brief review of the history of peritoneal dialysis in China is presented; this includes a description of pioneers and their important contributions, discussion of peritoneal dialysate, the technique of the use of Tenckhoff catheter, the use of continuous ambulatory peritoneal dialysis (CAPD) and dialysis registration. Current ongoing PD research activities among Chinese PD academicians are also discussed. Finally, we present four areas of future focus: 1) the promotion of PD in rural areas where PD use is still very limited due to the lack of PD awareness and education; 2) PD quality management and continuous quality improvement (CQI) program particularly focusing on PD adequacy and patient rehabilitation; 3) development and enforcement of national standards on PD management; 4) multi-center studies to compare the benefits of PD and hemodialysis (HD) that should include survival, rehabilitation and cost-effectiveness.

The history of hemodialysis in China

The technique of hemodialysis was introduced into China more than 50 years ago; and both research and use of clinical hemodialysis began in mid-1960s to late-1960s. A brief review of the history of hemodialysis in China is presented here, including a brief description of pioneers and their contributions, local development and use of dialyzers, hemodialysis machines, and vascular access, and dialysis management and logistics.

Infection-Related Hospitalizations in Home Hemodialysis Patients

INTRODUCTION AND AIMS

Infection is an important cause of hospitalization and death in patients receiving hemodialysis (HD). Few studies have examined infection-related hospitalizations in home HD (HHD) population. The purpose of this study was to examine the scope of infections and the effect of HHD modality (daily home HD (DHD) and conventional home HD (CHD)) on infection-related hospitalizations in HHD patients.

METHODS

The study was performed in a large cohort of HHD patients. Infection-related hospitalizations during July 1, 2005, and August 30, 2010, were abstracted from the centralized computer system. Data on demographics, dialysis vintage and dialysis modality were analyzed.

RESULTS

One hundred sixty-five patients were included. During a median follow-up of 5 years, infection-related hospitalizations were observed in approximately 35.8% of all hospitalizations, which was the first cause for hospitalization. Rates of non-access-related infections were observed to be higher than that of access-related infections (1.7:1). Rates (per 100 person-years) of soft-tissue infection, pneumonia and sepsis ranged from 0.85 to 1.82 in patients on HHD. Meanwhile, access-related infection was the main cause for access-related hospitalizations (34.8%). Cox regression analysis showed that the usage of different dialysis modalities was not associated with a high risk for infection-related hospitalizations in HHD patients.

CONCLUSIONS

Infection-related hospitalization occurred frequently in HHD patients. A broad range of infections, many unrelated to dialysis access, resulted in hospitalization in this population. HHD modalities were not associated with infection-related hospitalizations in HHD patients.

Effects of beta-blocker use on volume status in hemodialysis patients

BACKGROUND

Removal and control of excess fluid with dialysis is considered critical for protection against cardiovascular sequelae. Antihypertensive agents including beta-blockers may influence hemodynamics, which may limit fluid removal during hemodialysis (HD).

METHODS

Fifty chronic HD patients underwent bioimpedance measurement before and after a midweek dialysis session. Data on volume status, blood pressure, antihypertensive medications, and bioimpedance were analyzed.

RESULTS

Patients in the high-volume status group used a significantly higher percentage of beta-blockers than patients in the low-volume status group (54.2 vs. 19.2%, respectively, p = 0.01). Multivariable regression revealed that the use of beta-blockers was independently positively associated with fluid overload (p < 0.05). Intradialytic muscle cramping occurred more often in the beta-blocker group than the control group (44.4 vs. 12.5%, respectively, p = 0.02).

CONCLUSIONS

Our results suggest that the use of beta-blockers was associated with fluid overload in HD patients, and patients being treated with them experienced more intradialytic muscle cramping during dialysis.

Sex difference in the prevalence of left ventricular hypertrophy in dialysis patients

BACKGROUND

Left ventricular hypertrophy (LVH) is an important, independent negative predictor of cardiovascular morbidity and mortality in the general population and in dialysis patients. Previous studies suggest a sex dimorphism in the prevalence of LVH; however, this issue has never been approached in dialysis patients.

METHODS

This study enrolled 237 prevalent dialysis patients: 49 on hemodialysis (HD) and 188 on peritoneal dialysis (PD) from a single center. LVH was defined by echocardiography measurements, which were normalized to body surface area (BSA) and height(2.7), respectively.

RESULTS

The mean ages in HD and PD patients were 60 +/- 14 and 60 +/- 13 years, with a median dialysis vintage of 43 and 20 months, respectively. Although there was no significant difference in age, diabetes, proportion of uncontrolled hypertension, antihypertensive medication and blood pressure between male and female patients within each dialysis modality, the prevalence of LVH (whether indexed to BSA or height(2.7)) was consistently higher in females than in males. When these patients were divided into LVH or non-LVH groups, a significant difference in sex distribution was observed between the two groups (62.0% vs. 41.0% when the BSA-indexed standard was used, p < 0.01; 62.8% vs. 37.1% when the height(2.7)-indexed standard was used, p < 0.001). In logistic regression analysis, female sex was identified as a risk factor of LVH (odds ratio, OR = 2.48, 95% confidence interval, CI = 1.33-4.59; when BSA-indexed LVH was treated as dependent variable, and OR = 4.05, 95% CI = 1.96-8.38, when height(2.7)-indexed LVH was treated as dependent variable) even after adjustment for age, diabetes, blood pressure and antihypertensive medication.

CONCLUSION

This study showed that the prevalence of LVH determined by echocardiography was significantly higher in female dialysis patients than in male dialysis patients. Compared with males, female patients had a 2.5- to 4-fold higher risk to develop LVH even after adjustment for other potential confounding factors, which may indicate that elderly females in the uremic scenario are more prone to develop LVH than elderly males.

Stepwise increase in the prevalence of isolated systolic hypertension with the stages of chronic kidney disease

BACKGROUND

Hypertension is common in patients with chronic kidney disease (CKD), and isolated systolic hypertension (ISH) accounts for most patients with inadequate blood pressure (BP) control. However, it remains unclear whether the prevalence of ISH would increase with the advancement of CKD.

METHODS

CKD patients of stages 3, 4 and 5 were recruited (n = 324). Based on office systolic BP (SBP) and diastolic BP (DBP), they were classified into any of the four hypertensive subtypes: normotension (SBP/DBP <140/90 mmHg), isolated diastolic hypertension (IDH, SBP <140 mmHg and DBP >or=90 mmHg), ISH (SBP >or=140 mmHg and DBP <90 mmHg) and systolic-diastolic hypertension (SDH, SBP/DBP >or=140/90 mmHg).

RESULTS

The control rate was 45.7% at stage 3, which decreased with the advancement of CKD (control rate was 51.9%, 40.4% and 38.6% in stage 3, 4 and 5, respectively; P < 0.05). The prevalence of IDH changed from 5.0% to 5.3% and 0% from stage 3 to 4 and 5, while there was no significant change in the prevalence of SDH (15.0%, 14.9% and 15.7% at stage 3, 4 and 5, respectively). There was a stepwise increase in the prevalence of ISH with the stages of CKD (it was 28.1%, 39.4% and 45.7% in stage 3, 4 and 5, respectively). Logistic regression showed that age and CKD stages [compared with stage 3, stage 4 and 5 had 2.57 (95% CI 1.04-6.33) and 3.68 (95% CI 1.09-12.47) folds higher risk to develop ISH, respectively] were independent predictors of ISH.

CONCLUSION

The prevalence of ISH increased correspondingly with advanced stages of CKD, which may partially contribute to the increased cardiovascular mortality during the progress of CKD.

Volume overhydration is related to endothelial dysfunction in continuous ambulatory peritoneal dialysis patients

OBJECTIVE

In dialysis patients, volume overhydration is common and is related to increased risk of cardiovascular morbidity and mortality. However, it remains unclear whether volume overload imposes those detrimental effects through endothelial dysfunction.

METHODS

In this cross-sectional study, 81 stable patients on continuous ambulatory peritoneal dialysis in a single center were recruited. Volume status was evaluated by extracellular water, assessed by bioimpedance analysis, and normalized to individual height (nECW). Endothelial function was estimated by endothelial-dependent flow-mediated dilatation (FMD) of the brachial artery and expressed as percentage change relative to baseline diameter.

RESULTS

There were 37 male and 44 female patients (mean age 61 +/- 12 years, dialysis vintage 20 +/- 23 months). FMD in female patients was significantly higher than that in male patients (9.17% +/- 6.23% vs 6.31% +/- 5.01%, p < 0.05). FMD was negatively correlated with weight (r = -0.308, p < 0.01), body mass index (r = -0.242, p < 0.05), systolic blood pressure (r = -0.228, p < 0.05), ECW (r = -0.404, p < 0.001), and nECW (r = -0.418, p < 0.001). No correlation was found between FMD and other variables. In multiple stepwise regression analysis, calcium x phosphate product (beta = 0.422, p < 0.001), nECW (beta = -0.343, p < 0.01), and dialysis vintage (beta = -0.237, p < 0.05) were independent determinants of FMD (adjusted R(2) = 0.327 for this model).

CONCLUSION

There was independent correlation between index of volume status and FMD, and higher nECW was related to worse endothelial function. The results of this study may help us understand the underlying mechanism of volume overhydration leading to increased cardiovascular morbidity and mortality in dialysis patients.

Volume Overhydration is Related to Endothelial Dysfunction in Continuous Ambulatory Peritoneal Dialysis Patients

Objective

In dialysis patients, volume overhydration is common and is related to increased risk of cardiovascular morbidity and mortality. However, it remains unclear whether volume overload imposes those detrimental effects through endothelial dysfunction.

Methods

In this cross-sectional study, 81 stable patients on continuous ambulatory peritoneal dialysis in a single center were recruited. Volume status was evaluated by extracellular water, assessed by bioimpedance analysis, and normalized to individual height (nECW). Endothelial function was estimated by endothelial-dependent flow-mediated dilatation (FMD) of the brachial artery and expressed as percentage change relative to baseline diameter.

Results

There were 37 male and 44 female patients (mean age 61 ± 12 years, dialysis vintage 20 ± 23 months). FMD in female patients was significantly higher than that in male patients (9.17% ± 6.23% vs 6.31% ± 5.01%, p < 0.05). FMD was negatively correlated with weight ( r = -0.308, p < 0.01), body mass index ( r = -0.242, p < 0.05), systolic blood pressure ( r = -0.228, p < 0.05), ECW ( r = -0.404, p < 0.001), and nECW ( r = -0.418, p < 0.001). No correlation was found between FMD and other variables. In multiple stepwise regression analysis, calcium x phosphate product (² = 0.422, p < 0.001), nECW (² = -0.343, p < 0.01), and dialysis vintage (² = -0.237, p < 0.05) were independent determinants of FMD (adjusted R2 = 0.327 for this model).

Conclusion

There was independent correlation between index of volume status and FMD, and higher nECW was related to worse endothelial function. The results of this study may help us understand the underlying mechanism of volume overhydration leading to increased cardiovascular morbidity and mortality in dialysis patients.

The role of erythrocytes phosphatidylserine exposure in anemia in peritoneal dialysis patients

BACKGROUND

An increased red blood cell (RBC) phosphatidylserine (PS) exposure in uremic patients was found that could promote macrophage recognition and decrease RBC survival time. Furthermore, a reduced red cell life span was found to contribute anemia in patients with renal failure. It is therefore possible to hypothesize that increased PS externalization of RBC may influence renal anemia. The present study preliminarily explored the role of erythrocytes' PS exposure in anemia in uremic patients.

METHOD

Erythrocyte PS exposure was measured in 67 stable patients on continuous ambulatory peritoneal dialysis (CAPD). An investigation was conducted in the relationship between the level of erythrocyte PS exposure and hemoglobin concentration. A flow-cytometric assay based on FITC-Annexin V was used to measure the PS exposure of erythrocytes.

RESULTS

An inverse correlation was found between the percentage of PS-positive RBCs and hemoglobin concentration (r = -0.2601, p < 0.05). Logistic regression analysis revealed that the percentage of PS-positive RBCs was identified as a risk factor for anemia (Hazards ratio = -0.421, p < 0.05).

CONCLUSION

This study found that elevated PS exposure in erythrocytes might be a risk factor for anemia and contribute to the development of anemia in peritoneal dialysis patients.