Urine myo-inositol as a novel prognostic biomarker for diabetic kidney disease: a targeted metabolomics study using nuclear magnetic resonance

BACKGROUND

As a leading cause of chronic kidney disease, clinical demand for noninvasive biomarkers of diabetic kidney disease (DKD) beyond proteinuria is increasing. Metabolomics is a popular method to identify mechanisms and biomarkers. We investigated urinary targeted metabolomics in DKD patients.

METHODS

We conducted a targeted metabolomics study of 26 urinary metabolites in consecutive patients with DKD stage 1 to 5 (n = 208) and healthy controls (n = 26). The relationships between estimated glomerular filtration rate (eGFR) or urine protein-creatinine ratio (UPCR) and metabolites were evaluated. Multivariate Cox analysis was used to estimate relationships between urinary metabolites and the target outcome, end-stage renal disease (ESRD). C statistics and time-dependent receiver operating characteristics (ROC) were used to assess diagnostic validity.

RESULTS

During a median 4.5 years of follow-up, 103 patients (44.0%) progressed to ESRD and 65 (27.8%) died. The median fold changes of nine metabolites belonged to monosaccharide and tricarboxylic acid (TCA) cycle metabolites tended to increase with DKD stage. Myo-inositol, choline, and citrates were correlated with eGFR and choline, while mannose and myo-inositol were correlated with UPCR. Elevated urinary monosaccharide and TCA cycle metabolites showed associations with increased morality and ESRD progression. The predictive power of ESRD progression was high, in the order of choline, myo-inositol, and citrate. Although urinary metabolites alone were less predictive than serum creatinine or UPCR, myo-inositol had additive effect with serum creatinine and UPCR. In time-dependent ROC, myo-inositol was more predictive than UPCR of 1-year ESRD progression prediction.

CONCLUSION

Myo-inositol can be used as an additive biomarker of ESRD progression in DKD.

Elevated Ferritin Levels Associated with High Body Fat Mass Affect Mortality in Peritoneal Dialysis Patients

Obesity is a common health problem in peritoneal dialysis (PD) patients and causes high serum ferritin levels. However, mixed results have been reported on whether serum ferritin levels affect the prognosis of PD patients. We investigated the effect of increased adiposity on ferritin levels and its association with mortality in 350 well-nourished PD patients. Body composition was measured using a portable whole-body bioimpedance spectroscope, and clinical determinants of high ferritin levels were evaluated. High ferritin levels (≥600 ng/mL) were observed in 63 (18.0%) patients. Patients with high ferritin levels had a significantly higher body fat percentage and a lower lean tissue index than patients with low or normal ferritin levels. During a median follow-up of 30 months, there were 65 deaths. Ferritin ≥ 600 ng/mL was associated with significantly higher all-cause mortality compared with 200-600 ng/mL of ferritin. Multivariate analysis showed that high ferritin levels were significantly associated with a higher percentage of body fat after adjustment for lean tissue index and volume status. High ferritin increased all-cause mortality in PD patients, and increased fat mass was an important determinant of the high ferritin. Our results support that adiposity may lead to an adverse clinical outcome in PD patients.

Predicting outcomes of continuous renal replacement therapy using body composition monitoring: a deep-learning approach

Fluid balance is a critical prognostic factor for patients with severe acute kidney injury (AKI) requiring continuous renal replacement therapy (CRRT). This study evaluated whether repeated fluid balance monitoring could improve prognosis in this clinical population. This was a multicenter retrospective study that included 784 patients (mean age, 67.8 years; males, 66.4%) with severe AKI requiring CRRT during 2017-2019 who were treated in eight tertiary hospitals in Korea. Sequential changes in total body water were compared between patients who died (event group) and those who survived (control group) using mixed-effects linear regression analyses. The performance of various machine learning methods, including recurrent neural networks, was compared to that of existing prognostic clinical scores. After adjusting for confounding factors, a marginal benefit of fluid balance was identified for the control group compared to that for the event group (p = 0.074). The deep-learning model using a recurrent neural network with an autoencoder and including fluid balance monitoring provided the best differentiation between the groups (area under the curve, 0.793) compared to 0.604 and 0.606 for SOFA and APACHE II scores, respectively. Our prognostic, deep-learning model underlines the importance of fluid balance monitoring for prognosis assessment among patients receiving CRRT.

Development of New Equations Predicting the Mortality Risk of Patients on Continuous RRT

Background

Predicting the risk of death in patients admitted to the critical care unit facilitates appropriate management. In particular, among patients who are critically ill, patients with continuous RRT (CRRT) have high mortality, and predicting the mortality risk of these patients is difficult. The purpose of this study was to develop models for predicting the mortality risk of patients on CRRT and to validate the models externally.

Methods

A total of 699 adult patients with CRRT who participated in the VolumE maNagement Under body composition monitoring in critically ill patientS on CRRT (VENUS) trial and 1515 adult patients with CRRT in Seoul National University Hospital were selected as the development and validation cohorts, respectively. Using 11 predictor variables selected by the Cox proportional hazards model and clinical importance, equations predicting mortality within 7, 14, and 28 days were developed with development cohort data.

Results

The equation using 11 variables had area under the time-dependent receiver operating characteristic curve (AUROC) values of 0.75, 0.74, and 0.73 for predicting 7-, 14-, and 28-day mortality, respectively. All equations had significantly higher AUROCs than the Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores. The 11-variable equation was superior to the SOFA and APACHE II scores in the integrated discrimination index and net reclassification improvement analyses.

Conclusions

The newly developed equations for predicting CRRT patient mortality showed superior performance to the previous scoring systems, and they can help physicians manage patients.

Recent Increases in Influenza-Related Hospitalizations, Critical Care Resource Use, and In-Hospital Mortality: A 10-Year Population-Based Study in South Korea

Background: Long-term trends in influenza-related hospitalizations, critical care resource use, and hospital outcomes since the 2009 H1N1 influenza pandemic season have been rarely studied for adult populations. Materials and Methods: Adult patients from the Korean Health Insurance Review and Assessment Service who were hospitalized with influenza over a 10-year period (2009−2019) were analyzed. The incidence rates of hospitalization, critical care resource use, and in-hospital death were calculated using mid-year population census data. Results: In total, 300,152 hospitalized patients with influenza were identified (men, 35.7%; admission to tertiary hospitals, 9.4%). Although the age-adjusted hospitalization rate initially decreased since the 2009 H1N1 pandemic (52.61/100,000 population in 2009/2010), it began to increase again in 2013/2014 and reached a peak of 169.86/100,000 population in 2017/2018 (p < 0.001). The in-hospital mortality rate showed a similar increasing trend as the hospitalization, with a peak of 1.44/100,000 population in 2017/2018 (vs. 0.35/100,000 population in 2009/2010; p < 0.001). The high incidence rates of both hospitalization and in-hospital mortality were mainly attributable to patients aged ≥60 years. The rate of intensive care unit admission and the use of mechanical ventilation, continuous renal replacement therapy and vasopressors have also increased from the 2013/2014 season. The incidence of heart failure was the most frequent complication investigated, with a three-fold increase in the last two seasons since 2009/2010. In multivariate analysis adjusted for covariates, among hospitalized patients, type of hospitals and 2009 H1N1 pandemic season were associated with in-hospital mortality. Conclusions: We confirmed that the rates of hospitalization, critical care resource use, and in-hospital mortality by influenza have increased again in recent years. Therefore, strategies are needed to reduce infections and optimize resource use with a greater focus on older people.

Effect of once-weekly dulaglutide on renal function in patients with chronic kidney disease

Background

Dulaglutide is associated with improved cardiovascular and kidney outcomes and can be a good therapeutic option for patients with type 2 diabetes with chronic kidney disease (CKD). In this study, the effects of dulaglutide on glucose-lowering efficacy and changes in renal function were analyzed.

Methods

This retrospective study involved 197 patients with type 2 diabetes with mild-to-severe CKD treated with dulaglutide for at least 3 months between January 2017 and December 2020 at two tertiary hospitals in Korea. Changes in the creatinine-based estimated glomerular filtration rate (eGFR) and HbA1c were compared before and after the use of dulaglutide in each patient.

Results

The number of patients and mean eGFR (mL/min/1.73 m²) in CKD 2, 3a, 3b, and 4 were 94 (75.0 ± 8.5), 46 (54.8 ± 6.3), 31 (38.8 ± 4.4), and 26 (22.5 ± 5.4), respectively. Mean HbA1c level and body mass index (BMI) at the initiation of dulaglutide were 8.9% ± 1.4% and 29.1 ± 3.6 kg/m², the median duration of the use of dulaglutide was 16 months. The use of dulaglutide was associated with a mean decrease in HbA1c by 0.9% ± 1.5% and the glucose-lowering efficacy was similar across all stages of CKD. Also, it was associated with a reduced decline in the eGFR; the mean eGFR change after the use of dulaglutide was –0.76 mL/min/1.73 m² per year, whereas it was –2.41 mL/min/1.73 m² before use (paired t-test, P = 0.003). The difference was more pronounced in patients with an eGFR < 60 mL/min/1.73 m². Subgroup analysis showed that the renal protective effect was better in patients with proteinuria, age ≤ 65 years, and HbA1c < 9.0%, but showed no association with BMI.

Conclusions

The use of dulaglutide provided adequate glycemic control irrespective of CKD stage and was associated with a reduced decline in the eGFR in the CKD population.

High-flow arteriovenous fistula and myocardial fibrosis in hemodialysis patients with non-contrast cardiac magnetic resonance imaging

Background

The role of high-flow arteriovenous fistula (AVF) in cardiovascular morbidity in hemodialysis (HD) patients is very likely under-recognized. We assessed the relationship between high access flow (Qa) and myocardial fibrosis in HD patients.

Methods

Myocardial fibrosis was assessed by native T1 relaxation times on non-contrast cardiac magnetic resonance imaging and a potential marker of fibrosis. Serum levels of galectin-3, N-terminal pro-B-type natriuretic peptide (NT-proBNP), and monocyte chemoattractant protein 1 (MCP-1) were measured in 101 HD patients who underwent regular monitoring of AVF Qa. A high-flow AVF was defined as a Qa >2 L/min.

Results

Hemodialysis patients showed significantly higher galectin-3 value and increased T1 relaxation time compared to healthy volunteers, suggesting increased myocardial fibrosis in uremic cardiomyopathy. In HD patients, 20 (19.8%) had a Qa > 2L/min, and they had significantly higher cardiac output, cardiac index, left ventricular mass, and increased T1 times than those with a Qa ≤ 2 L/min. Also, serum galectin-3 and NT-proBNP levels were much higher in the high Qa group, indicating a close relationship between the high Qa, increased myocardial fibrosis, and the risk of heart failure (HF) in HD patients. It is interesting that a higher AVF Qa for myocardial fibrosis was independent of several traditional cardiovascular risk factors as well as serum levels of NT-proBNP and MCP-1.

Conclusions

A supra-physiologically high Qa can be related to myocardial fibrosis and increased risk of HF in HD patients. Regular Qa monitoring could allow early detection of a high-flow AVF that could arise cardiac complications.

Serum cystatin C to creatinine ratio is associated with sarcopenia in non-dialysis-dependent chronic kidney disease

Background

Methods

Results

Conclusion

First snapshot on behavioral characteristics and related factors of patients with chronic kidney disease in South Korea during the COVID-19 pandemic (June to October 2020)

Background

The recent novel coronavirus disease 2019 (COVID-19) pandemic has led to unprecedented changes in behavior. We evaluated the current status of precautionary behavior and physical activity in chronic kidney disease (CKD) patients during the COVID-19 pandemic.

Methods

A population of CKD patients (n = 306) registered in the Study on Kidney Disease and Environmental Chemicals (SKETCH, Clinical Trial No. NCT04679168) cohort recruited from June 2020 to October 2020 was included in the study. We conducted a questionnaire survey related to risk perception of COVID-19, precautionary behavior, and physical activity.

Results

There were 187 patients (61.1%) with estimated glomerular filtration rate of <45 mL/min/1.73 m². This population showed a higher degree of risk perception for COVID-19 than the general population. Age was the most significant determinant of risk perception among CKD patients. During the pandemic, social distancing and hygiene-related behavior were significantly increased (p < 0.001). The frequency of exercise was decreased only in those who took regular exercise, without diabetes, or with a lower Charlson comorbidity index (CCI) (p < 0.001), with no change among the other groups. Socioeconomic status and comorbidities significantly affected behavioral characteristics regardless of the category. Education and income were significantly associated with precautionary behaviors such as staying at home and hand sanitizer use. Patients with higher CCI status significantly increased frequency of exercise (adjusted odds ratio, 2.10; 95% confidence interval, 1.01–4.38).

Conclusion

CKD patients showed higher risk perception with active precautionary behavioral changes than the general population. Healthcare providers should be aware of the characteristics to comprise precautionary behavior without reducing physical activity.

When and why to start continuous renal replacement therapy in critically ill patients with acute kidney injury

Acute kidney injury (AKI) is a common condition in critically ill patients, and may contribute to significant medical, social, and economic consequences, including death. Although there have been advances in medical technology, including continuous renal replacement therapy (CRRT), the mortality rate of AKI is high, and there is no fundamental treatment that can reverse disease progression. The decision to implement CRRT is often subjective and based primarily on the clinician’s judgment without consistent and concrete guidelines or protocols regarding when to initiate and discontinue CRRT and how to manage complications. Recently, several randomized controlled trials addressing the initiation of renal replacement therapy in critically ill patients with AKI have been completed, but clinical application of the findings is limited by the heterogeneity of the objectives and research designs. In this review, the advantages and disadvantages of CRRT initiation, clinical guideline recommendations, and the results of currently published clinical trials and meta-analyses are summarized to guide patient care and identify future research priorities.

Effects of periostin deficiency on kidney aging and lipid metabolism

Periostin plays a crucial role in fibrosis, which is involved in kidney aging. A few studies have shown that lipid metabolism is involved in kidney aging. We investigated the role of periostin in lipid metabolism during kidney aging. Renal function, fibrosis, and inflammatory markers were studied using urine, blood, and tissue samples from wild-type (WT) C57BL/6 mice and Postn-null mice of 2 and 24 months of age. Lipids were quantitatively profiled using liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring mode. Renal function was worse and tubular atrophy/interstitial fibrosis, periostin expression, and inflammatory and fibrotic markers were more severe in aged WT mice than in young WT mice. In aged Postn-null mice, these changes were mitigated. Thirty-five differentially regulated lipids were identified. Phosphatidylcholines, cholesteryl ester, cholesterol, ceramide-1-phosphate, and CCL5 expression were significantly higher in aged WT mice than in aged Postn-null mice. Particularly, linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid differed strongly between the two groups. Lysophosphatidylcholine acyltransferase 2, which converts lysophosphatidylcholine to phosphatidylcholine, was significantly higher in aged WT mice than in aged Postn-null mice. Periostin expression in the kidneys increased with age, and periostin ablation delayed aging. Changes in lipids and their metabolism were found in Postn-null mice. Further research on the precise mechanisms of and relationships between lipid expression and metabolism, kidney aging, and periostin expression is warranted.

Hepatocyte growth factor and soluble cMet levels in plasma are prognostic biomarkers of mortality in patients with severe acute kidney injury

Background

Hepatocyte growth factor (HGF)/cMet pathway is necessary for repair and regeneration following acute kidney injury (AKI). We evaluated the clinical potential of plasma HGF and soluble cMet as prognostic biomarkers for severe AKI requiring continuous renal replacement therapy (CRRT).

Methods

One hundred thirty-six patients with severe AKI who participated in the VENUS (volume management under body composition monitoring in critically ill patients on CRRT) trial between 2017 and 2019 were enrolled in this study. We investigated associations between plasma HGF and cMet concentrations and all-cause mortality.

Results

Plasma HGF and soluble cMet levels were positively correlated. Patients were divided into three groups based on their HGF and soluble cMet concentrations. The day D 0, D2, and D7 highest concentration HGF groups had significantly higher in-hospital mortality after adjusting for sex, body mass index, Acute Physiology and Chronic Health Evaluation II, and age-adjusted Charlson comorbidity index score, especially on D7 (hazard ratio, 4.26; 95% confidence interval, 1.71–10.62; p = 0.002). D7 soluble cMet level was also associated with mortality. Receiver operating characteristic curve analysis indicated that D7 HGF and soluble cMet levels were best at predicting mortality. Addition of plasma HGF and soluble cMet to conventional prognostic indices significantly improved the predictive value for mortality on D7. However, plasma HGF and soluble cMet were not associated with fluid status.

Conclusion

Plasma HGF and soluble cMet levels were significant predictors of the outcomes of severe AKI patients undergoing CRRT. There was no correlation between plasma HGF and soluble cMet levels and fluid balance.

Neutrophil extracellular traps and heparin-induced antibodies contribute to vascular access thrombosis in hemodialysis patients

Background

Anti-heparin/platelet factor 4 (PF4) antibodies may trigger severe thrombotic complications in hemodialysis (HD) patients. Tetrameric PF4 has a high affinity for extracellular DNA, which is a key component of neutrophil extracellular traps (NETs); therefore, the interactions between anti-heparin/PF4 antibodies and NETs can contribute to prothrombotic events.

Methods

Anti-heparin/PF4 antibody levels were measured by enzyme-linked immunosorbent assay and an optical density > 1.8 was regarded as clinically significant. We additionally measured serum nucleosome levels as representative markers of NETs, and the contributions of anti-heparin/PF4 and increased serum nucleosome levels to the primary functional patency loss of vascular access was assessed.

Results

The frequency of anti-heparin/PF4 antibodies was significantly higher in incident HD patients compared to prevalent HD patients (23.6% vs. 7.7%). Serum nucleosome levels, as well as the white blood cell counts, neutrophil counts, and high- sensitivity C-reactive protein levels, were significantly higher in anti-heparin/PF4 antibody-positive patients compared to the control. Platelet counts tended to be lower in the patients with anti-heparin/PF4 of >1.8 than in the controls. Relative risk calculations showed that the presence of anti-heparin/PF4 antibodies increased the risk of primary functional patency failure by 4.28-fold, and this risk increased further with higher nucleosome levels. Furthermore, in the anti-heparin/PF4 antibody-positive group, the time to first vascular intervention was much shorter, and the risk of repeated intervention was higher, compared to the controls.

Conclusion

In incident HD patients, the presence of anti-heparin/PF4 antibodies was associated with increased NET formation; this could be a strong predictor of vascular access complications

Mortality predictors in critically ill patients with acute kidney injury requiring continuous renal replacement therapy

Background

Because of high cost of continuous renal replacement therapy (CRRT) and the high mortality rate among severe acute kidney injury patients, careful identification of patients who will benefit from CRRT is warranted. This study determined factors associated with mortality among critically ill patients requiring CRRT.

Methods

This was a retrospective observational study of 414 patients admitted to the intensive care unit of four hospitals in South Korea who received CRRT from June 2017 to September 2018. Patients were divided according to degree of fluid overload (FO) and disease severity. The Cox proportional hazards model was used to explore the effect of relevant variables on mortality.

Results

In-hospital mortality rate was 57.2%. Ninety-day mortality rate was 58.5%. Lower creatinine and blood pH were significant predictors of mortality. A one-unit increase in the Sequential Organ Failure Assessment (SOFA) score was associated with increased risk of and 90-day mortality (hazard ratio [HR], 1.07; p < 0.001). The risk of 90-day mortality in FO patients was 57.2% (p < 0.001) higher than in those without FO. High SOFA score was associated with increased risk for 90-day mortality (HR, 1.79; p = 0.03 and HR, 3.05; p = 0.001) in patients without FO and with FO ≤ 10%, respectively. The highest mortality rates were in patients with FO > 10%, independent of disease severity.

Conclusion

FO increases the risk of mortality independent of other factors, including severity of acute illness. Prevention of FO should be a priority, especially when managing the critically ill.

cMet agonistic antibody prevents acute kidney injury to chronic kidney disease transition by suppressing Smurf1 and activating Smad7

We aimed to investigate the role of cMet agonistic antibody (cMet Ab) in preventing kidney fibrosis during acute kidney injury (AKI) to chronic kidney disease (CKD) transition. Additionally, we explored the effect of cMet Ab on TGF-β1/Smad pathway during the pathogenesis of kidney fibrosis. A unilateral ischemia-reperfusion injury (UIRI) mouse model was established to induce AKI-to-CKD transition. Furthermore, we incubated human proximal tubular epithelial cells (hPTECs) under hypoxic conditions as in vitro model of kidney fibrosis. We analyzed the soluble plasma cMet level in patients with AKI requiring dialysis. Patients who did not recover kidney function and progressed to CKD presented a higher increase in the cMet level. The kidneys of mice treated with cMet Ab showed fewer contractions and weighed more than the controls. The mice in the cMet Ab-treated group showed reduced fibrosis and significantly decreased expression of fibronectin and α-smooth muscle actin. cMet Ab treatment decreased inflammatory markers (MCP-1, TNF-α, and IL-1β) expression, reduced Smurf1 and Smad2/3 level, and increased Smad7 expressions. cMet Ab treatment increased cMet expression and reduced the hypoxia-induced increase in collagen-1 and ICAM-1 expression, thereby reducing apoptosis in the in vitro cell model. After cMet Ab treatment, hypoxia-induced expression of Smurf1, Smad2/3, and TGF-β1 was reduced, and suppressed Smad7 was activated. Down-regulation of Smurf1 resulted in suppression of hypoxia-induced fibronectin expression, whereas treatment with cMet Ab showed synergistic effects. cMet Ab can successfully prevent fibrosis response in UIRI models of kidney fibrosis by decreasing inflammatory response and inhibiting the TGF-β1/Smad pathway.

NK1.1- natural killer T cells upregulate interleukin-17 expression in experimental lupus nephritis

Interleukin (IL)-17-secreting invariant natural killer T (NKT) cells are involved in several inflammatory diseases. However, their role in lupus nephritis (LN) has not been fully characterized. Samples from patients with LN or glomerulonephritis and healthy controls were obtained, and elevated IL-17+ NKT cell numbers and IL-17 expression were observed in blood cells and kidneys, respectively, in patients with LN. Comparison of a mouse model of experimental autoimmune LN with the parental strain (NKT-deficient B6.CD1d-/- mice) revealed improved proteinuria, disease severity, and histopathology and decreased levels of chemokine (C-X-C motif) ligand 16 and T cell receptor-α variable 14 expression. Spleens and kidneys of B6.CD1d-/- mice also showed downregulation of inflammatory markers and IL-17. In coculture with renal mesangial and NKT cells, inflammatory markers and IL-17 were upregulated following α-galactosylceramide treatment and downregulated after treatment with IL-17-blocking antibodies. This was most prominent with killer cell lectin-like receptor subfamily B member 1 C (NK1.1)- NKT cells. Thus, IL-17 is upregulated in LN. Activation of NKT cells regulates IL-17-related immune responses systemically and in the kidneys, primarily via NK1.1- NKT cells. IL-17-secreting NK1.1- NKT cells could serve as diagnostic and therapeutic targets for LN.NEW & NOTEWORTHY This study makes a significant contribution to the literature because our results indicate that IL-17 is upregulated in lupus nephritis and that natural killer T (NKT) cells are involved in its pathogenesis. Activation of NKT cells regulates IL-17-related immune responses, both systemically and in the kidney, and this mainly involves NK1.1- NKT cells. Furthermore, IL-17-secreting NK1.1- NKT cells could serve as a diagnostic and therapeutic target for lupus nephritis.

Low serum total CO2 and its association with mortality in patients being followed up in the nephrology outpatients clinic

Large-scale studies have not been conducted to assess whether serum hypobicarbonatemia increases the risk for kidney function deterioration and mortality among East-Asians. We aimed to determine the association between serum total CO₂ (TCO₂) concentrations measured at the first outpatient visit and clinical outcomes. In this multicenter cohort study, a total of 42,231 adult nephrology outpatients from 2001 to 2016 were included. End-stage renal disease (ESRD) patients on dialysis within 3 months of the first visit were excluded. Instrumental variable (IV) was used to define regions based on the proportion of patients with serum TCO₂ < 22 mEq/L. The crude mortality rate was 12.2% during a median 77.0-month follow-up period. The Cox-proportional hazard regression model adjusted for initial kidney function, alkali supplementation, and the use of diuretics demonstrated that low TCO₂ concentration was not associated with progression to ESRD, but significantly increased the risk of death. The IV analysis also confirmed a significant association between initial TCO₂ concentration and mortality (HR 0.56; 95% CI 0.49–0.64). This result was consistently significant regardless of the underlying renal function. In conclusion, low TCO₂ levels are significantly associated with mortality but not with progression to ESRD in patients with ambulatory care.

Cumulative fluid balance and mortality in elderly patients with acute kidney injury requiring continuous renal-replacement therapy: a multicenter prospective cohort study

Background

The effect of fluid balance on outcomes in elderly patients with acute kidney injury (AKI) requiring continuous renal-replacement therapy (CRRT) is not explained well. We investigated outcomes according to cumulative fluid balance (CFB) in elderly patients with AKI undergoing CRRT.

Methods

A total of 607 patients aged 65 years or older who started CRRT due to AKI were enrolled and stratified into two groups (fluid overload [FO] vs. no fluid overload [NFO]) based on the median CFB value for 72 hours before CRRT initiation. Propensity score-matching analysis was performed.

Results

The median age of included patients was 73.0 years and 60.0% of the population was male. The median 72-hour CFB value was 2,839.0 mL. The overall cumulative survival and 28-day survival rates were lower in the FO group than in the NFO group (P < 0.001 for both) and remained so after propensity score-matching. Furthermore, patients in the FO group demonstrated a higher overall mortality risk after adjustment for age, sex, systolic blood pressure, Charlson comorbidity index, Acute Physiology and Chronic Health Evaluation II score, serum albumin, creatinine, diuretic use, and mechanical ventilation status (hazard ratio, 1.38; 95% confidence interval, 1.13 to 1.89; P < 0.001). Among survivors, both the duration of CRRT and the total duration of hospitalization from CRRT initiation showed no difference between the FO and NFO groups.

Conclusion

A higher CFB value is associated with an increased risk of mortality in elderly patients with AKI requiring CRRT.

Impact of health-related quality of life on survival after dialysis initiation: a prospective cohort study in Korea

Background

The effect of each health-related quality of life (HRQOL) component on hemodialysis prognosis has not been well studied. We aimed to investigate the clinical factors associated with HRQOL and the effect of HRQOL after dialysis initiation on long-term survival in an Asian population.

Methods

A total of 568 hemodialysis patients were included from a nationwide prospective cohort study. HRQOL was evaluated using the Kidney Disease Quality of Life (KDQOL) Short FormTM 1.3 at 3 months after dialysis initiation. The effect of each KDQOL item score on mortality was analyzed. Multivariable Cox analysis was performed after adjusting for age, sex, modified Charlson comorbidity index, and causes of primary kidney disease.

Results

Old age, diabetes mellitus, high comorbidities, and low serum albumin levels were associated with poor physical health status. Decreased urine output was associated with both poor physical and mental health status. The scores of 3 indices in the kidney disease domain (effect of kidney disease, social support, and dialysis staff encouragement) showed significant associations with mortality, as did the 3 indices (physical function, physical role limitation, and body pain) in the physical health domain. Neither the 4 indices in the mental health domain nor the mental composite score showed a significant association with mortality. However, a high physical composite score was associated with decreased overall patient mortality (P = 0.003). The effect of physical composite score on survival was prominent among young or middle-aged groups.

Conclusion

Poor physical health status 3 months after hemodialysis start correlates significantly with overall mortality.

Association Between a Polymorphism in MBOAT7 and Chronic Kidney Disease in Patients With Biopsy-Confirmed Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) and chronic kidney disease (CKD) share risk factors, and recent meta-analysis confirmed that NAFLD is an independent risk factor for incident CKD.¹ Genetic variants associated with NAFLD, such as patatin-like phospholipase domain-containing-3 (PNPLA3) rs738409² and transmembrane 6 superfamily member 2 (TM6SF2) rs5854292,² have been reported to be associated with renal function in NAFLD subjects.

Association of exposure to phthalates and environmental phenolics with markers of kidney function: Korean National Environmental Health Survey (KoNEHS) 2015-2017

Increasing number of consumer chemicals have been associated with chronic kidney disease (CKD) in human populations. However, many studies that investigated estimated glomerular filtration rate (eGRF) as an outcome reported inconsistent associations. In the present study, we employed a subset (n = 1292) of a nationally representative adult population participating in Korean National Environmental Health Survey (KoNEHS) 2015-2017, and assessed associations of major phthalates, bisphenol A (BPA), and parabens with both eGRF and albuminuria. In order to address a potential collider issue, a covariate-adjusted standardization method was applied, in addition to the conventional creatinine-correction, for adjusting urine dilution. Regardless of adjustment method, urinary DEHP metabolites showed significant positive associations with albumin to creatinine ratio (ACR). In addition, urinary metabolites of other heavy molecular weight phthalates such as MCOP and MCNP showed significant positive associations with ACR in the female population, but only following the covariate-adjusted standardization. For eGFR, conventional creatinine-correction resulted in positive associations with most of measured phthalate metabolites. However, with the covariate-adjusted standardization, most of positive associations with eGFR disappeared, and instead, significant negative associations were observed for MnBP, BPA, and EtP. Secondary analysis following stratification by CKD status, as well as principal component analysis (PCA), generally supported the observed associations. The present observations highlight the importance of urine dilution adjustment method for association studies on eGFR, and suggest potential effects of several consumer chemicals on adverse kidney function among humans.

Biobanking for glomerular diseases: a study design and protocol for KOrea Renal biobank NEtwoRk System TOward NExt-generation analysis (KORNERSTONE)

Backgrounds

Glomerular diseases, a set of debilitating and complex disease entities, are related to mortality and morbidity. To gain insight into pathophysiology and novel treatment targets of glomerular disease, various types of biospecimens linked to deep clinical phenotyping including clinical information, digital pathology, and well-defined outcomes are required. We provide the rationale and design of the KOrea Renal biobank NEtwoRk System TOward Next-generation analysis (KORNERSTONE).

Methods

The KORNERSTONE, which has been initiated by Korea Centres for Disease Control and Prevention, is designed as a multi-centre, prospective cohort study and biobank for glomerular diseases. Clinical data, questionnaires will be collected at the time of kidney biopsy and subsequently every 1 year after kidney biopsy. All of the clinical data will be extracted from the electrical health record and automatically uploaded to the web-based database. High-quality digital pathologies are obtained and connected in the database. Various types of biospecimens are collected at baseline and during follow-up: serum, urine, buffy coat, stool, glomerular complementary DNA (cDNA), tubulointerstitial cDNA. All data and biospecimens are processed and stored in a standardised manner. The primary outcomes are mortality and end-stage renal disease. The secondary outcomes will be deterioration renal function, remission of proteinuria, cardiovascular events and quality of life.

Discussion

Ethical approval has been obtained from the institutional review board of each participating centre and ethics oversight committee. The KORNERSTONE is designed to deliver pioneer insights into glomerular diseases. The study design allows comprehensive, integrated and high-quality data collection on baseline laboratory findings, clinical outcomes including administrative data and digital pathologic images. This may provide various biospecimens and information to many researchers, establish the rationale for future more individualised treatment strategies for glomerular diseases.

Trial registration

NCT03929887.

Urinary cMet as a prognostic marker in immunoglobulin A nephropathy

The prediction of prognosis in patients with immunoglobulin A nephropathy (IgAN) is challenging. We investigated the correlation between urinary cMet (ucMet) levels and clinical parameters and examined the effects of cMet agonistic antibody (cMet Ab) in an in vitro IgAN model. Patients diagnosed with IgAN (n = 194) were divided into three groups representing undetectable (Group 1), below‐median (Group 2) and above‐median (Group 3) levels of ucMet/creatinine (ucMet/Cr). Stained kidney biopsy samples were graded according to cMet intensity. Primary‐cultured human mesangial cells were stimulated with recombinant tumour necrosis factor (TNF)‐α and treated with cMet Ab. Our results showed that ucMet/Cr levels positively correlated with proteinuria (P < .001). During the follow‐up, patients in Group 3 showed a significantly lower probability of complete remission (CR; uPCr < 300 mg/g) than those in groups 1 and 2, after adjusting for blood pressure, estimated glomerular filtration rate, and proteinuria, which influence clinical prognosis (HR 0.60, P = .038); moreover, ucMet/Cr levels were also associated with glomerular cMet expression. After TNF‐α treatment, the proliferation of mesangial cells and increased interleukin‐8 and intercellular adhesion molecule‐1 expression were markedly reduced by cMet Ab in vitro. In conclusion, ucMet/Cr levels significantly correlated with proteinuria, glomerular cMet expression, and the probability of CR. Further, cMet Ab treatment alleviated the inflammation and proliferation of mesangial cells. Hence, ucMet could serve as a clinically significant marker for treating IgAN.

An independent validation of the kidney failure risk equation in an Asian population

Predicting the risk of end-stage renal disease (ESRD) progression facilitates appropriate nephrology care of patients with chronic kidney disease (CKD). Previously, the kidney failure risk equations (KFREs) were developed and validated in several cohorts. The purpose of this study is to validate the KFREs in a Korean population and to recalibrate the equations. A total of 38,905 adult patients, including 13,244 patients with CKD stages G3–G5, who were referred to nephrology were recruited. Using the original KFREs (4-, 6- and 8-variable equations) and recalibration equations, we predicted the risk of 2- and 5-year ESRD progression. All analyses were conducted in CKD stages G3-G5 patients as well as the total population. In CKD stages G3–G5 patients, All the original 4-, 6- and 8-variable equations showed excellent areas under the receiver operating characteristic curve of 0.87 and 0.83 for the 2- and 5-year risk of ESRD, respectively. The results of net reclassification improvement, integrated discrimination index and Brier score showed that recalibration improved the prediction models in some cases. The original KFREs showed high discrimination in both CKD stages G3–G5 patients and the total population referred to nephrology in this large Korean cohort. KFREs can be implemented in Korean health systems and can guide nephrology referrals and other CKD-related treatment decisions.

P0502BIOBANKING FOR GLOMERULAR DISEASES: A STUDY DESIGN AND PROTOCOL FOR KOREA RENAL BIOBANK NETWORK SYSTEM TOWARD NEXT-GENERATION ANALYSIS (KORNERSTONE)

Background and Aims

Glomerular diseases, a set of debilitating and complex disease entities, are related to mortality and morbidity. To gain insight into pathophysiology and novel treatment targets of glomerular disease, various types of biospecimens linked to deep clinical phenotyping including clinical information, digital pathology, and well-defined outcomes are required. We provide the rationale and design of the KOrea Renal biobank NEtwoRk System TOward Next-generation analysis (KORNERSTONE).

Method

The KORNERSTONE, which has been initiated by Korea Centres for Disease Control and Prevention, is designed as a multi-centre, prospective cohort study and biobank for glomerular diseases. Clinical data, questionnaires will be collected at the time of kidney biopsy and subsequently every one year after kidney biopsy. All of the clinical data will be extracted from the electrical health record and automatically uploaded to the web-based database. High-quality digital pathologies are obtained and

connected in the database. Various types of biospecimens are collected at baseline and during follow-up: serum, urine, buffy coat, stool, glomerular complementary DNA (cDNA), tubulointerstitial cDNA. All data and biospecimens are processed and stored in a standardised manner. The primary outcomes are mortality and end-stage renal disease. The secondary outcomes will be deterioration renal function, remission of proteinuria, cardiovascular events and quality of life.

Disussion

Ethical approval has been obtained from the institutional review board of each participating centre and ethics oversight committee. The KORNERSTONE is designed to deliver pioneer insights into glomerular diseases. The study design allows comprehensive, integrated and high-quality data collection on baseline laboratory findings, clinical outcomes including administrative data and digital pathologic images. This may provide various biospecimens and information to many researchers, establish the rationale for future more individualised treatment strategies for glomerular diseases.

Conclusion

In conclusion, we describe the objectives and clinical protocol for the KORNERSTONE. As the first large-scale glomerulonephropathy cohort study with the integration of clinical data, biospecimens and digital pathologic images in Korea, the KORNERSTONE will help to clarify the natural course, complication profiles, and novel treatment targets of the Asian population with glomerular disease.

Environment-Wide Association Study of CKD

BACKGROUND AND OBJECTIVES

Exposure to environmental chemicals has been recognized as one of the possible contributors to CKD. We aimed to identify environmental chemicals that are associated with CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We analyzed the data obtained from a total of 46,748 adults who participated in the National Health and Nutrition Examination Survey (1999-2016). Associations of chemicals measured in urine or blood (n=262) with albuminuria (urine albumin-to-creatinine ratio ≥30 mg/g), reduced eGFR (<60 ml/min per 1.73 m²), and a composite of albuminuria or reduced eGFR were tested and validated using the environment-wide association study approach.

RESULTS

Among 262 environmental chemicals, seven (3%) chemicals showed significant associations with increased risk of albuminuria, reduced eGFR, or the composite outcome. These chemicals included metals and other chemicals that have not previously been associated with CKD. Serum and urine cotinines, blood 2,5-dimethylfuran (a volatile organic compound), and blood cadmium were associated with albuminuria. Blood lead and cadmium were associated with reduced eGFR. Blood cadmium and lead and three volatile compounds (blood 2,5-dimethylfuran, blood furan, and urinary phenylglyoxylic acid) were associated with the composite outcome. A total of 23 chemicals, including serum perfluorooctanoic acid, seven urinary metals, three urinary arsenics, urinary nitrate and thiocyanate, three urinary polycyclic aromatic hydrocarbons, and seven volatile organic compounds, were associated with lower risks of one or more manifestations of CKD.

CONCLUSIONS

A number of chemicals were identified as potential risk factors for CKD among the general population.

The Long-term Effects of Metformin on Patients With Type 2 Diabetic Kidney Disease

OBJECTIVE

Metformin is the first pharmacological option for treating type 2 diabetes. However, the use of this drug is not recommended in individuals with impaired kidney function because of the perceived risk of lactic acidosis. We aimed to assess the efficacy and safety of metformin in patients with type 2 diabetic kidney disease (DKD).

RESEARCH DESIGN AND METHODS

We conducted a retrospective observational cohort study of 10,426 patients with type 2 DKD from two tertiary hospitals. The primary outcomes were all-cause mortality and end-stage renal disease (ESRD) progression. The secondary outcome was metformin-associated lactic acidosis. Taking into account the possibility that patients with less severe disease were prescribed metformin, propensity score matching (PSM) was conducted.

RESULTS

All-cause mortality and incident ESRD were lower in the metformin group according to the multivariate Cox analysis. Because the two groups had significantly different baseline characteristics, PSM was performed. After matching, metformin usage was still associated with lower all-cause mortality (adjusted hazard ratio [aHR] 0.65; 95% CI 0.57-0.73; P < 0.001) and ESRD progression (aHR 0.67; 95% CI 0.58-0.77; P < 0.001). Only one event of metformin-associated lactic acidosis was recorded. In both the original and PSM groups, metformin usage did not increase the risk of lactic acidosis events from all causes (aHR 0.92; 95% CI 0.668-1.276; P = 0.629).

CONCLUSIONS

In the present retrospective study, metformin usage in advanced chronic kidney disease (CKD) patients, especially those with CKD 3B, decreased the risk of all-cause mortality and incident ESRD. Additionally, metformin did not increase the risk of lactic acidosis. However, considering the remaining biases even after PSM, further randomized controlled trials are needed to change real-world practice.

cMet agonistic antibody attenuates apoptosis in ischaemia-reperfusion-induced kidney injury

Acute kidney injury (AKI) is a very common complication with high morbidity and mortality rates and no fundamental treatment. In this study, we investigated whether the hepatocyte growth factor (HGF)/cMet pathway is associated with the development of AKI and how the administration of a cMet agonistic antibody (Ab) affects an AKI model. In the analysis using human blood samples, cMet and HGF levels were found to be significantly increased in the AKI group, regardless of underlying renal function. The administration of a cMet agonistic Ab improved the functional and histological changes after bilateral ischaemia‐reperfusion injury. TUNEL‐positive cells and Bax/Bcl‐2 ratio were also reduced by cMet agonistic Ab treatment. In addition, cMet agonistic Ab treatment significantly increased the levels of PI3K, Akt and mTOR. Furthermore, after 24 hours of hypoxia induction in human proximal tubular epithelial cells, treatment with the cMet agonistic Ab also showed dose‐dependent antiapoptotic effects similar to those of the recombinant HGF treatment. Even when the HGF axis was blocked with a HGF‐blocking Ab, the cMet agonistic Ab showed an independent dose‐dependent antiapoptotic effect. In conclusion, cMet expression is associated with the occurrence of AKI. cMet agonistic Ab treatment attenuates the severity of AKI through the PI3K/Akt/mTOR pathway and improves apoptosis. cMet agonistic Ab may have important significance for the treatment of AKI.

Factors affecting mortality during the waiting time for kidney transplantation: A nationwide population-based cohort study using the Korean Network for Organ Sharing (KONOS) database

BACKGROUND

Long waiting time for deceased donor kidney transplant is inevitable due to the scarcity of donor, resulting in highlighting the importance of waiting time care. We analyzed the Korean Network for Organ Sharing (KONOS) database to assess the impact of waiting time on post-transplant survival outcomes and investigate risk factors for mortality by waiting time based on a complete enumeration survey in Korea.

METHODS

We analyzed all persons aged over 18 years in deceased donor kidney transplant cases enrolled in the Korean Network for Organ Sharing (KONOS) database from January 2000 to January 2015. The primary end point was all-cause mortality after enrollment.

RESULTS

Of the 24,296 wait-listed subjects on dialysis, 5,255 patients received kidney transplants from deceased donors, with a median waiting time of 4.5 years. Longer waiting times had distinct deleterious effects on overall survival after transplantation. While waiting for a transplant, patients with diabetes were more likely to die before transplantation (HR 1.515, 95% CI 1.388-1.653, p<0.001). Age was another significant risk factor for mortality. Only 56% of people aged 65 years survived after 10 years of waiting, whereas 86% of people aged 35 years survived after 10 years. Moreover, women on the waiting list were more likely to live longer than men on the list.

CONCLUSIONS

More attention should be focused on patients with a higher risk of mortality while waiting for a deceased donor kidney transplant, such as patients with diabetes, those of advanced age, and those who are male.

p38 MAPK activity is associated with the histological degree of interstitial fibrosis in IgA nephropathy patients

Activation of p38 mitogen-activated protein kinase (MAPK) is associated with tissue fibrosis, and inhibition of p38 MAPK can attenuate the progression of fibrosis. We aimed to investigate whether p38 MAPK activity in kidney tissue confirmed by immunohistochemical staining is associated with renal tubulointerstitial fibrosis in chronic kidney disease patients with IgA nephropathy. We collected kidney biopsy specimens from 341 IgA nephropathy patients and 15 control patients to identify the clinical and histopathological factors associated with kidney tubulointerstitial fibrosis and to find an association between kidney phosphorylated p38 immunoactivity and pathological grading. In addition, we aimed to investigate whether the anti-fibrotic effect of p38 MAPK inhibition can be identified by assessing the immunostaining intensity of phosphorylated p38 in kidney tissue. A renal tubulointerstitial fibrosis model was introduced using 7-week-old C57BL/6 mice subjected to unilateral ureteral obstruction (UUO). The p38 MAPK inhibitor SB-731445 was injected intraperitoneally every day for 7 days, and changes in renal fibrosis-associated markers were investigated. Assessment of kidney biopsy specimens from IgA nephropathy patients revealed that the degree of interstitial fibrosis was significantly associated with the tissue immunoactivity of phosphorylated p38. High-grade interstitial fibrosis was associated with a low glomerular filtration rate, high proteinuria, and high-grade histopathological changes, including tubular atrophy, interstitial inflammation, and glomerular sclerosis. In a mouse UUO model, renal protein expression of COL1 and phosphorylated p38 were significantly increased, and the protein expression of COL1 and phosphorylated p38 decreased in mice administered 10 mg/kg/day p38 MAPK inhibitor. We found that kidney interstitial fibrosis is associated with increased immunoactivity of phosphorylated p38 in a UUO mouse model and in human IgA nephropathy patients and that the anti-fibrotic effect of p38 MAPK inhibition can be confirmed using immunohistochemical staining for phosphorylated p38 in kidney tissue.

The impact of sunlight exposure on mortality of patients with end stage renal disease

Recent data suggest that reduced sunlight exposure is associated with increased mortality in the general population. To date, the association between sunlight exposure and mortality in dialysis patients has not been examined. Among 134,478 dialysis patients in the Korean end-stage renal disease (ESRD) cohort from 2001 to 2014, 31,291 patients were enrolled from seven metropolitan cities, and data were analyzed using bi-directional case-crossover design. We examined the association between short-term sunlight exposure and mortality in ESRD patients. We adjusted for temperature, humidity, and daily concentrations of nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), carbon monoxide (CO), and particle matter (PM₁₀) as confounders. The characteristics of the study population included age (65.6 ± 12.26 (mean ± standard deviation [SD]) years), sex (male, 59.96%; female, 41.04%), comorbidity (diabetes, 53.58%; hypertension, 40.5%), and kidney dialysis type (hemodialysis, 73.02%; peritoneal dialysis, 26.98%). The mean ± SD follow-up time was 4.68 ± 4.37 years. The daily sunlight exposure was significantly decreased in the case group compared with the control group (P = 0.004). Sunlight exposure was associated with all-cause death overall (ORs [95% CI]: 0.99 [0.98-0.99], P = 0.042) in a fully adjusted model. Patients with diabetes (ORs [95% CI]: 0.98 [0.97-0.99], P = 0.016) or aged higher than 75 years (ORs [95% CI]; 0.97 [0.96-0.99], P = 0.020) had higher risks of mortality than patients without diabetes or aged below 75 years, respectively. These findings suggest that sunlight exposure is inversely correlated with all-cause mortality in dialysis patients.

Periostin induces kidney fibrosis after acute kidney injury via the p38 MAPK pathway

Periostin plays a crucial role in fibrosis, and acute kidney injury results in a high risk of progression to chronic kidney disease. Therefore, we hypothesized that periostin was involved in the progression of acute kidney injury to kidney fibrosis. Unilateral ischemia-reperfusion injury (UIRI) was induced in 7- to 8-wk-old male wild-type and periostin-null mice, and the animals were observed for 6 wk. In vitro, human kidney-2 cells and primary-cultured human tubular epithelial cells were incubated under hypoxic conditions (5% O₂, 5% CO₂, and 90% N₂) for 5 days. The cells were also cultured with recombinant periostin (rPeriostin) and a p38 mitogen-activated protein kinase (MAPK) inhibitor in a hypoxic incubator. At 6 wk after UIRI, interstitial fibrosis/tubular atrophy was significantly alleviated in periostin-null mice compared with wild-type controls. In addition, periostin-null mice had attenuated expression of fibrosis/apoptosis markers and phosphorylated-p38 MAPK compared with wild-type controls. In vitro, hypoxic injury increased the expression of fibrosis markers, periostin, and phosphorylated-p38 MAPK, which was comparable to or substantially greater than their expression levels following treatment with recombinant transforming growth factor-β1 under normoxic conditions. Furthermore, rPeriostin treatment under hypoxic conditions enhanced fibrosis/apoptosis markers and phosphorylated-p38 MAPK. In contrast, p38 MAPK inhibition ameliorated hypoxia-induced fibrosis, and the addition of the p38 MAPK inhibitor to rPeriostin significantly ameliorated the changes induced by rPeriostin. In conclusion, periostin promotes kidney fibrosis via the p38 MAPK pathway following acute kidney injury triggered by a hypoxic or ischemic insult. Periostin ablation may protect against chronic kidney disease progression.

VolumE maNagement Under body composition monitoring in critically ill patientS on CRRT: study protocol for a randomized controlled trial (VENUS trial)

Background

Despite recent technical advances in the management of acute kidney injury (AKI), such as continuous renal replacement therapy (CRRT), intensive care unit mortality is still high, at approximately 40 to 50%. Although several factors have been reported to predict mortality in AKI patients, fluid overload (FO) during CRRT is a well-known predictor of patient survival. However, FO has been mostly quantified as an arithmetical calculation and determined on the basis of the physicians’ perception. Even though such quantification and assessment provides an easy evaluation of a patient’s fluid status and is a simple method, it is not applicable unless a detailed record of fluid monitoring is available. Furthermore, the method cannot differentiate excess water in individual water compartments but can only reflect excess total body water. Bioimpedance analysis (BIA) has been used to measure the nutritional component of body composition and is a promising tool for the measurement of volume status. However, there has been no prospective interventional study for fluid balance among CRRT-treated AKI patients using BIA. Therefore, we will investigate the usefulness of fluid management using the InBody S10 (InBody®, Seoul, Korea), a BIA tool, compared with that of generally used quantification methods.

Methods/design

This will be a multicenter, prospective, randomized controlled trial. A total of 244 patients undergoing CRRT treatment will be enrolled and randomly assigned to receive either to InBody S10-guided management or to fluid management based only on clinical information for 7 days. The primary outcome is to compare the rate of euvolemic status 7 days after the initiation of CRRT, with a secondary outcome being to compare the 28-, 60-, and 90-day mortality rates between the two groups.

Discussion

This will be the first clinical trial to investigate the effect of using BIA-guided fluid management to achieve euvolemia in CRRT-treated AKI patients.

Trial registration

ClinicalTrials.gov, ID: NCT03330626. Registered on 6 November 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3056-y) contains supplementary material, which is available to authorized users.

Epidemiology of continuous renal replacement therapy in Korea: Results from the National Health Insurance Service claims database from 2005 to 2016

Background

Continuous renal replacement therapy (CRRT) is an important treatment modality for severe acute kidney injury. As such, the epidemiology of CRRT in Korea needs further investigation.

Methods

We conducted a nationwide, population-based study analyzing the claims data from National Health Insurance Service of Korea. All index intensive care unit admission cases of CRRT in government-designated tertiary referral hospitals in Korea from 2005 to 2016 were included. Patients with a history of renal replacement therapy or who were under 20 years old were not considered. In addition to baseline and treatment characteristics, patient outcomes, including all-cause mortality and renal survival rates, were investigated. We stratified the study patients according to 3-year time periods and major regions of the nation.

Results

We included 37,337 patients who received CRRT in Korea. The overall use of CRRT increased over time, and more than 80% of cases of acute renal replacement therapy were CRRT after 2014. Seoul was the region in which the majority of CRRT (45.0%) was performed. The clinical characteristics of CRRT patients were significantly different among time-intervals and regions. Both all-cause mortality and renal survival rates after CRRT were prominently improved in the recent time periods (P < 0.001).

Conclusion

CRRT is a widely used treatment strategy for severe acute kidney injury in Korea. The prognosis of CRRT patients has improved compared to the past. This epidemiological study of CRRT in Korea revealed notable trends with regard to time period and geographic region.

Effectiveness of group cognitive behavioral therapy with mindfulness in end-stage renal disease hemodialysis patients

Background

Many patients with end-stage renal disease (ESRD) undergoing hemodialysis (HD) experience depression. Depression influences patient quality of life (QOL), dialysis compliance, and medical comorbidity. We developed and applied a group cognitive behavioral therapy (CBT) program including mindfulness meditation for ESRD patients undergoing HD, and measured changes in QOL, mood, anxiety, perceived stress, and biochemical markers.

Methods

We conducted group CBT over a 12-week period with seven ESRD patients undergoing HD and suffering from depression. QOL, mood, anxiety, and perceived stress were measured at baseline and at weeks 8 and 12 using the World Health Organization Quality of Life scale, abbreviated version (WHOQOL-BREF), the Beck Depression Inventory II (BDI-II), the Hamilton Rating Scale for Depression (HAM-D), the Beck Anxiety Inventory (BAI), and the Perceived Stress Scale (PSS). Biochemical markers were measured at baseline and after 12 weeks. The Temperament and Character Inventory was performed to assess patient characteristics before starting group CBT.

Results

The seven patients showed significant improvement in QOL, mood, anxiety, and perceived stress after 12 weeks of group CBT. WHOQOL-BREF and the self-rating scales, BDI-II and BAI, showed continuous improvement across the 12-week period. HAM-D scores showed significant improvement by week 8; PSS showed significant improvement after week 8. Serum creatinine levels also improved significantly following the 12 week period.

Conclusion

In this pilot study, a CBT program which included mindfulness meditation enhanced overall mental health and biochemical marker levels in ESRD patients undergoing HD.

Active maintenance of endothelial cells prevents kidney fibrosis

Background

Soluble epoxide hydrolase (sEH) expressed by endothelial cells catalyzes the metabolism of epoxyeicosatrienoic acids (EETs), which are vasoactive agents.

Methods

We used a unilateral ureteral obstruction mouse model of kidney fibrosis to determine whether inhibition of sEH activity reduces fibrosis, the final common pathway for chronic kidney disease.

Results

sEH activity was inhibited by continuous release of the inhibitor 12-(3-adamantan-1-ylureido)-dodecanoic acid (AUDA) for 1 or 2 weeks. Treatment with AUDA significantly ameliorated tubulointerstitial fibrosis by reducing fibroblast mobilization and enhancing endothelial cell activity. In an in vitro model of endothelial-to-mesenchymal transition (EndMT) using human vascular endothelial cells (HUVECs), AUDA prevented the morphologic changes associated with EndMT and reduced expression of fibroblast-specific protein 1. Furthermore, HUVECs activated by AUDA prevented the epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells in a co-culture system.

Conclusion

Our findings suggest that regulation of sEH is a potential target for therapies aimed at delaying the progression of kidney fibrosis by inhibiting EndMT and EMT.

Experimental Inhibition of Periostin Attenuates Kidney Fibrosis

BACKGROUND

Periostin is responsible for tissue regeneration, fibrosis, and wound healing via its interaction with integrin. Recently, the role of periostin has been shown to contribute to fibrosis in chronic kidney disease. We investigated the role of periostin and the effect of periostin blockade in renal fibrogenesis.

METHODS

We investigated the function of periostin in vivo in wild-type and periostin-null mice (Postn-KO) in a unilateral ureteral obstruction (UUO) model. For the in vitro experiments, primary cultured inner medullary collecting duct cells from the wild-type and Postn-KO mice were used.

RESULTS

Periostin expression was strongly induced by UUO in the wild-type mice. UUO induced renal fibrosis and morphological changes in the obstructed kidney of wild-type mice, whereas global knockout of periostin reduced fibrosis induced by UUO and improved kidney structure. Fibrosis- and inflammation-related mRNA were significantly induced in the wild-type mice and were decreased in the Postn-KO mice. Additionally, α-smooth muscle actin expression was increased following the administration of recombinant periostin in vitro. The effect of periostin blockade was examined using 2 methods. The integrin blockade peptide decreased fibrosis-related gene expression in in vitro experiments. Anti-periostin polyclonal antibody attenuated renal fibrosis induced by UUO through changes in transforming growth factor-β signaling and the inflammatory and apoptotic pathways.

CONCLUSION

Periostin is a marker of renal fibrosis and may augment the progression of fibrogenesis as an extracellular matrix protein. Periostin blockade effectively attenuated renal fibrogenesis. Thus, periostin inhibition may be a therapeutic strategy for the amelioration of renal disease progression.

Association between postoperative hyponatremia and renal prognosis in major urologic surgery

Recent evidence for the clinical significance of postoperative hyponatremia after urologic surgeries remains scarce. We examined the incidence, risk factors, and outcomes of electrolyte imbalance in urologic surgery. Patients with newly developed hyponatremia, defined as a sodium level lower than 135 mEq/L within 7 days after surgery, were included in our study group. The primary outcome was progression to end-stage renal disease (ESRD). Secondary outcome was composition of progression to ESRD and creatinine doubling/eGFR halving from baseline. A survival analysis with a multivariable Cox proportional hazard model was performed. We included 9,206 cases of bladder, prostate, ureter, and kidney surgery. Incidence of new-onset postoperative hyponatremia was 15.4% (1,414/9,206). Postoperative hyponatremia mostly developed in patients with high-risk perioperative characteristics. The development of postoperative hyponatremia was independently associated with progression to ESRD (adjusted HR 1.343, 95% CI 1.082-1.680, P = 0.007). The secondary outcome was also related to the electrolyte imbalance in prostate (adjusted HR 1.729, 95% CI 1.145-2.612, P = 0.009) and kidney (adjusted HR 1.339, 95% CI 1.099-1.632, P = 0.004) surgery. Postoperative hyponatremia in urologic surgery was a common electrolyte imbalance in patients with high-risk perioperative status, and associated with worse renal prognosis.

Discrepancies in Clinic and Ambulatory Blood Pressure in Korean Chronic Kidney Disease Patients

Blood pressure (BP) control is considered the most important treatment for preventing chronic kidney disease (CKD) progression and associated cardiovascular complications. However, clinic BP is insufficient to diagnose hypertension (HT) and to monitor overall BP control because it does not correlate well with ambulatory blood pressure monitoring (ABPM). We enrolled 387 hypertensive CKD patients (stages G1-G4, 58.4% male with median age 61 years) from 3 hospitals in Korea. HT of clinic BP and ABPM was classified as ≥ 140/90 and ≥ 130/80 mmHg, respectively. Clinic BP control rate was 60.2%. The median 24-hour systolic blood pressures (SBPs) of CKD G3b and CKD G4 were significantly higher than those of CKD G1-2 and CKD G3a. However, the median 24-hour SBPs were not different between CKD G1-2 and CKD G3a or between CKD G3b and CKD G4. Of all patients, 5.7%, 38.0%. 42.3%, and 14.0% were extreme-dippers, dippers, non-dippers, and reverse-dippers, respectively. Non-/reverse-dippers independently correlated with higher Ca × P product, higher intact parathyroid hormone (iPTH), and lower albumin. Normal BP was 33.3%, and sustained, masked, and white-coat HT were 29.7%, 26.9%, and 10.1%, respectively. White-coat HT independently correlated with age ≥ 61 years and masked HT independently correlated with CKD G3b/G4. In conclusion, ABPM revealed a high prevalence of non-/reverse-dippers and sustained/masked HT in Korean CKD patients. Clinicians should try to obtain a CKD patient's ABPM, especially among those who are older or who have advanced CKD as well as those with abnormal Ca × P product, iPTH, and albumin.

The prognostic significance of preoperative left ventricular diastolic dysfunction and left atrial enlargement on acute coronary syndrome in kidney transplantation

Echocardiography is commonly performed as a screening test to evaluate perioperative risks before kidney transplantation. However, only limited data are available on echocardiographic parameters of left ventricular diastolic dysfunction (LVDD) and left atrial enlargement (LAE) on acute coronary syndrome and mortality in kidney transplant recipients. We reviewed 2779 adult recipients who underwent pretransplant echocardiography from 1997 to 2012. We divided the patients into two and four groups by two categories: LVDD grades 0-1 vs. 2-3, and left atrial size quartile groups. During a mean follow-up of 4.5 years, acute coronary syndrome occurred in 89 (3.2%) patients. The recipients with LVDD grades 2-3 (P = 0.005 for non-fatal, P = 0.02 for fatal/non-fatal) and LAE (P = 0.001 for non-fatal, P = 0.03 for fatal/non-fatal) had a higher incidence of acute coronary syndrome after kidney transplantation. All-cause mortality did not differ significantly between the groups. In a multivariate analysis, LVDD of grades 2-3 (hazard ratio 2.98, 95% confidence interval 1.535-5.787; P = 0.001), and LAE (hazard ratio 1.052, 95% confidence interval 1.006-1.101; P = 0.03) were independently associated with non-fatal acute coronary syndrome. In patients who are kidney transplant candidates, pretransplant LVDD and LAE were independently associated with a higher incidence of acute coronary syndrome after kidney transplantation.

Soluble Tumor Necrosis Factor Receptors and Arterial Stiffness in Patients With Coronary Atherosclerosis

BACKGROUND

Soluble forms of tumor necrosis factor receptors (sTNFRs) are emerging target molecules of inflammatory disease. However, their role in vascular biology is not well known. This study was performed to investigate the association between serum concentrations of sTNFRs and arterial stiffness.

METHODS

A total of 117 consecutive patients with suspected coronary artery disease (CAD) (63.6 ± 11.0 years; men, 65%) who were referred for invasive coronary angiography (ICA) were prospectively enrolled. Arterial blood sTNFR1 and sTNFR2 were measured using commercially available ELISA kits. Brachial-ankle pulse wave velocity (baPWV) measurements were made within 24 hours of blood sampling for sTNFRs measurement.

RESULTS

Most of the patients (86.3%) had significant CAD (stenosis ≥ 50%) in ICA. In simple linear regression analyses, there were significant positive correlations of baPWV with sTNFR1 (r = 0.483, P < 0.001) and sTNFR2 (r = 0.366, P < 0.001). In multiple linear regression analyses, sTNFR1 (β = 0.316, P < 0.001) and sTNFR2 (β = 0.235, P = 0.005) had independent association with baPWV even after controlling for potential confounders.

CONCLUSION

sTNFR1 and sTNFR2 were independently associated with baPWV in patients undergoing ICA. This result may extend previous knowledge on close interactions between inflammation and arterial stiffening.

Urinary Periostin Excretion Predicts Renal Outcome in IgA Nephropathy

BACKGROUND

Periostin is a matricellular protein and plays a vital role in tissue regeneration, fibrosis and wound healing. However, data about its significance in nephrology are limited. We investigated the correlation between urinary periostin excretion and its clinical significance including renal histologic findings and prognosis in IgA nephropathy (IgAN).

METHODS

Of 399 patients from a glomerulonephritis cohort recruited between January 2009 and December 2014, 314 were enrolled. Serum and urine periostin (uPOSTN) were measured using enzyme-linked immunosorbent assay. We divided the patients into 3 groups by uPOSTN/creatinine (uPOSTN/Cr): group 1 (undetectable), group 2 (lower than the median) and group 3 (higher than the median).

RESULTS

The uPOSTN level was correlated with pathologic classifications and both initial and final IDMS-MDRD estimated glomerular filtration rates (eGFRs; p < 0.001). Histologically, group 3 patients were correlated with severe interstitial fibrosis/tubular atrophy (p = 0.004), interstitial inflammation (p = 0.007), hyaline arteriolosclerosis (p = 0.001) and glomerular sclerosis (p < 0.001). A higher initial uPOSTN/Cr level was associated with a greater decline in eGFR during follow-up (p = 0.043 when initial eGFR ≥60; p = 0.025 when eGFR <60 ml/min/1.73 m2), and the renal outcomes with end-stage renal disease (ESRD; p = 0.003), ESRD and/or eGFR decrease of >30% (p = 0.033) and ESRD and/or eGFR decrease of >50% (p = 0.046) occurred significantly more in group 3. In multivariate analysis, uPOSTN group 3 (hazards ratio 2.839, 95% CI 1.013-7.957; p = 0.047) was independently associated with ESRD in IgAN patients.

CONCLUSION

uPOSTN/Cr value at initial diagnosis correlated with renal fibrosis and predicted the renal outcomes in patients with IgAN. It could be a promising urinary biomarker for renal fibrosis.

Early initiation of continuous renal replacement therapy improves survival of elderly patients with acute kidney injury: a multicenter prospective cohort study

Background

Continuous renal replacement therapy (CRRT) is essential in the management of critically ill patients with acute kidney injury (AKI). However, the optimal timing for initiating CRRT remains controversial, especially in elderly patients. Therefore, we investigated the outcomes of early CRRT initiation in elderly patients with AKI.

Methods

A total of 607 patients ≥65 years of age who started CRRT due to AKI between August 2009 and December 2013 were prospectively enrolled. They were divided into two groups based on the median 6-hour urine output immediately before CRRT initiation. Propensity score matching was used to compare the overall survival rate, CRRT duration, and hospitalization duration.

Results

The median age of both groups was 73.0 years, and 60 % of the patients were male. The most common cause of AKI was sepsis. In the early CRRT group, the mean arterial pressure was higher, but the prothrombin time and total bilirubin, aspartate aminotransferase, and alanine aminotransferase levels were lower. The overall cumulative survival rate was higher in the early CRRT group (log-rank P < 0.01). Late CRRT initiation was associated with a higher mortality rate than early initiation after adjusting for age, sex, the Charlson comorbidity index, systolic arterial pressure, prothrombin time, the total bilirubin, aspartate aminotransferase, and alanine aminotransferase levels, cumulative fluid balance and diuretic use (hazard ratio, 1.35; 95 % confidence interval 1.06, 1.71, P = 0.02). Following propensity score matching, patient survival was significantly better in the early CRRT group than in the late CRRT group (P < 0.01). The total duration of hospitalization from the start of CRRT was shorter among the survivors when CRRT was started earlier (26.7 versus 39.1 days, P = 0.04).

Conclusion

A better prognosis can be expected if CRRT is applied early in the course of AKI in critically ill, elderly patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1437-8) contains supplementary material, which is available to authorized users.

Pre-Transplant Cardiovascular Risk Factors Affect Kidney Allograft Survival: A Multi-Center Study in Korea

Background

Pre-transplant cardiovascular (CV) risk factors affect the development of CV events even after successful kidney transplantation (KT). However, the impact of pre-transplant CV risk factors on allograft failure (GF) has not been reported.

Methods and Findings

We analyzed the graft outcomes of 2,902 KT recipients who were enrolled in a multi-center cohort from 1997 to 2012. We calculated the pre-transplant CV risk scores based on the Framingham risk model using age, gender, total cholesterol level, smoking status, and history of hypertension. Vascular disease (a composite of ischemic heart disease, peripheral vascular disease, and cerebrovascular disease) was noted in 6.5% of the patients. During the median follow-up of 6.4 years, 286 (9.9%) patients had developed GF. In the multivariable-adjusted Cox proportional hazard model, pre-transplant vascular disease was associated with an increased risk of GF (HR 2.51; 95% CI 1.66–3.80). The HR for GF (comparing the highest with the lowest tertile regarding the pre-transplant CV risk scores) was 1.65 (95% CI 1.22–2.23). In the competing risk model, both pre-transplant vascular disease and CV risk score were independent risk factors for GF. Moreover, the addition of the CV risk score, the pre-transplant vascular disease, or both had a better predictability for GF compared to the traditional GF risk factors.

Conclusions

In conclusion, both vascular disease and pre-transplant CV risk score were independently associated with GF in this multi-center study. Pre-transplant CV risk assessments could be useful in predicting GF in KT recipients.

Superior outcomes of kidney transplantation compared with dialysis: An optimal matched analysis of a national population-based cohort study between 2005 and 2008 in Korea

Data regarding kidney transplantation (KT) and dialysis outcomes are rare in Asian populations. In the present study, we evaluated the clinical outcomes associated with KT using claims data from the Korean national public health insurance program. Among the 35,418 adult patients with incident dialysis treated between 2005 and 2008 in Korea, 1539 underwent KT. An optimal balanced risk set matching was attempted to compare the transplant group with the control group in terms of the overall survival and major adverse cardiac event-free survival. Before matching, the dialysis group was older and had more comorbidities. After matching, there were no differences in age, sex, dialysis modalities, or comorbidities. Patient survival was significantly better in the transplant group than in the matched control group (P < 0.001). In addition, the transplant group showed better major adverse cardiac event-free survival than the dialysis group (P < 0.001; hazard ratio, 0.49; 95% confidence interval, 0.32-0.75). Korean patients with incident dialysis who underwent long-term dialysis had significantly more cardiovascular events and higher all-cause mortality rates than those who underwent KT. Thus, KT should be more actively recommended in Korean populations.

Posttransplant Hyponatremia Predicts Graft Failure and Mortality in Kidney Transplantation Recipients: A Multicenter Cohort Study in Korea

Although hyponatremia is related to poorer outcomes in several clinical settings, its significance remains unresolved in kidney transplantation. Data on 1,786 patients who received kidney transplantations between January 2000 and December 2011 were analyzed. The patients were divided into two groups according to the corrected sodium values for serum glucose 3 months after their transplantations (<135 mmol/L vs. ≥135 mmol/L). Subsequently, the hazard ratios (HRs) for biopsy-proven acute rejection, graft failure, and all-cause mortality were calculated after adjustments for several immunological and non-immunological covariates. 4.0% of patients had hyponatremia. Patients with hyponatremia had higher risks for graft failure and all-cause mortality than did the counterpart normonatremia group; the adjusted HRs for graft failure and mortality were 3.21 (1.47-6.99) and 3.03 (1.21-7.54), respectively. These relationships remained consistent irrespective of heart function. However, hyponatremia was not associated with the risk of acute rejection. The present study addressed the association between hyponatremia and graft and patient outcomes in kidney transplant recipients. Based on the study results, our recommendation is to monitor serum sodium levels after kidney transplantations.

Factors Affecting the Referral Time to Nephrologists in Patients With Chronic Kidney Disease: A Prospective Cohort Study in Korea

Timely referral to nephrologists is important for improving clinical outcomes and reducing costs during transition periods. We evaluated the impact of patients' demographic, clinical, and social health characteristics on referral time.A total of 1744 CKD patients who started maintaining dialysis were enrolled in a Korean prospective cohort. The early referral (ER) and late referral group (LR) were defined as patients who were referred to a nephrologist more than or less than 1 year prior to dialysis initiation, respectively.A total of 1088 patients (62.3%) were in the ER, and 656 patients (37.6%) were in the LR. Among the patients in the LR, 398 patients (60.7%) were referred within the 3 months prior to the start of dialysis (ultralate referral group [ULR]). The ER was younger at the time of referral than the LR; however, the ER was older at the start of dialysis. Patients with diabetes or hypertension as the cause of kidney disease were more common in the LR, whereas patients with glomerulonephritis, females, and nonsmokers were more common in the ER. The ER had more well-controlled blood pressure, lower phosphorus levels, and higher hemoglobin levels at the start of dialysis. Congestive heart failure (CHF) was more common in the LR. In the multivariate analysis, male sex (odds ratio [OR] 1.465, 95% confidence interval [CI] 1.034-2.076), underlying kidney disease (diabetes mellitus [OR 1.507, 95% CI 1.057-2.148] and hypertension [OR 1.995, 95% CI 1.305-3.051]), occupation (mechanician [OR 2.975, 95% CI 1.445-6.125], laborer [OR 3.209, 95% CI 1.405-7.327], and farmer [OR 5.147, 95% CI 2.217-11.953]), CHF (OR 2.152, 95% CI 1.543-3.000), and ambulatory status (assisted-walks, OR 2.072, 95% CI 1.381-3.111) were proved as the independent risk factor for late referral.Patients with hypertensive or diabetic kidney disease are referred later than those with glomerulonephritis. Male patients with physically active occupations exhibiting CHF and restricted ambulation were associated with a late referral. Considering the various factors associated with late referral, efforts to increase early referrals should be emphasized, particularly in patients with hypertension, diabetes, or congestive heart failure.