Dietary zinc intake and incident chronic kidney disease

BACKGROUND & AIMS

Previous studies have shown that dietary zinc intake is closely related to cardiovascular complications and metabolic derangements. However, the effect of dietary zinc intake on renal function is not fully elucidated.

METHODS

Data from the Korean Genome and Epidemiology Study were used. Dietary zinc intake was assessed by a Food Frequency Questionnaire and dietary zinc density was calculated as absolute zinc intake amount per daily energy intake (mg/1000 kcal day). The participants were categorized into quartiles according to dietary zinc density. The primary end point was incident chronic kidney disease (CKD), defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m².

RESULTS

A total of 7735 participants with normal renal function was included in the final analysis. The mean age was 52.0 ± 8.8 years, 47.5% were male, and mean eGFR was 92.1 ± 16.1 ml/min/1.73 m². The mean daily zinc intake and zinc intake density were 8.6 ± 3.4 mg and 4.4 ± 0.9 mg/1000 kcal, respectively. During a median follow up of 11.5 (1.7-12.5) years and 70,617 person-years of observation, CKD developed in 1409 (18.2%) participants. Multivariable cox hazard analysis revealed that risk for CKD development was significantly higher in the quartile with a mean zinc intake density of 3.6 ± 0.2 mg/1000 kcal compared with the quartile with a mean zinc intake density of 5.6 ± 1.0 mg/1000 kcal (Hazard ratio; 1.36; 95% Confidence Interval 1.18-1.58; P < 0.001). This relationship remained significant even after adjustments for confounding factors.

CONCLUSION

Low dietary zinc intake may increase the risk of CKD development in individuals with normal renal function.

Prognostic value of soluble ST2 and soluble LR11 on mortality and cardiovascular events in peritoneal dialysis patients

Background

Although the soluble form of suppression of tumorigenicity 2 (sST2) and soluble low-density lipoprotein receptor relative with 11 ligand-binding repeats (sLR11) have emerged as novel cardiovascular biomarkers in patients with cardiovascular disease, their prognostic value has not been fully investigated in peritoneal dialysis (PD) patients.

Methods

We included 74 prevalent PD patients from a prospective cohort and measured serum sST2 and sLR11 concentrations by an enzyme-linked immunosorbent assay. The association of these biomarkers and all-cause mortality and major adverse cardiac and cerebrovascular events (MACCEs) was evaluated.

Results

During a follow-up of 38.5 months, all-cause deaths and MACCEs were observed in 13 (17.6%) patients and 23 (31.3%) patients. Multivariable Cox analyses demonstrated that greater sST2 was independently associated with higher risk of all-cause mortality (≥75.8 ng/mL; hazard ratio [HR] = 5.551; 95% confidence interval [CI] = 1.360–22.660) and MACCEs (≥72.5 ng/mL; HR = 4.609; 95% CI = 1.608–13.208). Furthermore, sST2 showed additive predictive value for mortality to the base model including traditional risk factors (net reclassification index = 0.598, P = 0.04). sLR11 was not significantly associated with all-cause mortality or MACCE.

Conclusions

sST2, but not sLR11, indicated a significant prognostic value for all-cause mortality and cardiovascular events in PD patients. Further research is needed to validate emerging biomarkers in these populations.

P0618PREOPERATIVE LOW URINE SPECIFIC GRAVITY PREDICTS ACUTE KIDNEY INJURY AFTER CARDIAC SURGERY

Background and Aims

Acute kidney injury (AKI) is a common and serious complication following cardiac surgery. However, strategies that effectively predict AKI risk before cardiac surgery are scarce. Recent investigations identified urinary osmolality to be associated with non-glomerular kidney damage in normal kidney function individuals, suggesting urine concentration ability to be a surrogate of early kidney damage. Therefore, hypothesizing that urine specific gravity (SG) could reflect asymptomatic kidney damage, the clinical implication of preoperative urine specific gravity on AKI occurrence after cardiac surgery was investigated in subjects with normal kidney function.

Method

A total of 4135 patients who underwent coronary artery bypass or valve surgery at Yonsei University Health System from were enrolled. Patients whose eGFR was lower than 60mL/min/1.73m2 were excluded. Fasting urinary SG was measured from the morning first void a day before the surgery. The patients were divided into tertiles based on urine SG. The primary outcome was occurrence of AKI within 48hours of cardiac surgery. AKI was defined according to Acute Kidney Injury Network criteria.

Results

The mean age of the patients was 60 years and 60% were male. Diabetes consisted of 25.6% of the patients and 54.5% were hypertensive. The mean eGFR and urine SG was 98.8mL/min/1.73m2 and 1.020, respectively. AKI developed in 1,089 (26.3%) patients. The incidence of AKI was highest in the lowest urine SG tertile group (410, 29.0%) and lowest in the highest tertile group (304, 23.5%) (P &lt; 0.001). Multivariable logistic regression analysis revealed that being included in the lowest preoperative urine SG tertile group was significantly related with higher post cardiac surgery AKI incidence risk (odd ratio (OR), 1.33; CI, 1.12-1.57; P =0.001). This association was significant even after adjustments were made for confounding factors.

Conclusion

Low urine SG was associated with increased risk of cardiac surgery associated AKI in patient with normal renal function. Evaluating preoperative urine SG may be useful in stratifying post cardiac surgery AKI risk.

P0628CREATININE-CYSTATIN C RATIO IS ASSOCIATED WITH MORTALITY IN ICU PATIENTS UNDERGOING CONTINUOUS RENAL REPLACEMENT THERAPY

Background and Aims

Development of acute kidney injury (AKI) in intensive care patients considerably increases the risk of mortality. Although several factors that are related to outcome have been recognized in this patient group, stratifying mortality risk still remains a challenge. While serum creatinine levels are confounded by muscle wasting in critical illness, cystatin C is expected to be less modulated by muscle mass. Speculating that the ratio between serum creatinine and cystatin C may reflect muscle mass in critically ill AKI patients, we evaluated the association between creatinine-cystatin C ratio and mortality in patients requiring continuous renal replacement therapy (CRRT) in the intensive care unit (ICU).

Method

Retrospective analyses were conducted on 443 ICU patients who underwent CRRT between August 2009 and October 2016 at Severance Hospital of Yonsei University Health System, Seoul, South Korea. The patients were divided into four groups based on creatinine-cystatin C ratio at the time of CRRT commencement. The primary outcome was 90-day mortality after CRRT initiation.

Results

The mean age was 64 ± 15 years, and 57.3% of patients were male. The most common cause of AKI was sepsis. The median and range of the creatinine-cystatin C ratio was 0.83 (0.13-6.20). The 90-day mortality rate for each creatinine-cystatin C ratio quartiles 1, 2, 3, and 4 were 76.6%, 73.9%, 61.3%, and 51.8%, respectively. Multiple Cox proportional hazard models revealed that the creatinine-cystatin C ratio was an independent predictor of 90-day mortality even after adjusting for confounding factors (Hazard ratio, 0.97; 95% confidence interval, 0.95-0.99, P&lt;0.01). The prediction of mortality was significantly improved when creatinine-cystatin C ratio was considered compared to APACHE-II or SOFA scores alone.

Conclusion

Creatinine-cystatin C ratio is associated with mortality in ICU patients undergoing CRRT, and may be a practical marker in predicting survival among ICU patients with AKI.

P0682PSYCHOLOGICAL STRESS AS A RISK FACTOR FOR RENAL FUNCTION DECLINE

Background and Aims

Accumulating evidences propose that psychological stress leads to changes in biological processes or behavioral patterns that effects disease risks. Supporting this possibility, recent animal experiments and population studies show a probable link between psychological stress and cardiovascular and metabolic diseases. However, the association between psychological stress and kidney function is not well elucidated yet.

Method

Data were retrieved from a prospective community-based cohort study (Korean Genome and Epidemiology Study). Psychological distress was assessed as the primary exposure using PWI-SF (psychosocial well-being index short form) scores. The decline rate of estimated glomerular filtration rate (eGFR) over time was calculated using linear regression analysis of serial eGFR measurements for each subject. Rapid eGFR decline was defined as an average decline in eGFR ≥3 ml/min/1.73 m2 per year.

Results

In total, 6,968 participants were analyzed. During a median follow-up of 10.49 years, rapid eGFR decline was observed in 886 (12.7%) participants. When the participants were categorized into tertiles according to PWI-SF score, rapid eGFR decline was more prevalent in the highest PWI-SF score group (14.0%) compared to the lowest PWI-SF score group (11.1%). Multivariate logistic regression analyses revealed that the risk of rapid eGFR decline was significantly increased in the highest PWI-SF score group compared to the lowest group (odds ratio, 2.04; 95% confidence interval 1.27-3.27). When PWI-SF score was treated as a continuous variable, each 1 standard deviation increase in PWI-SF was associated with a 12% increased risk of rapid eGFR decline.

Conclusion

The amount of psychological stress was significantly associated with an increased risk of rapid renal function decline in participants with normal renal function.

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.

High muscle-to-fat ratio is associated with lower risk of chronic kidney disease development

BACKGROUND

Obesity, a known risk factor for chronic kidney disease (CKD), is generally assessed using body mass index (BMI). However, BMI may not effectively reflect body composition, and the impact of muscle-to-fat (MF) mass balance on kidney function has not been elucidated. This study evaluated the association between body muscle and fat mass balance, represented as the MF ratio, and incident CKD development.

METHODS

Data were retrieved from a prospective community-based cohort study (Korean Genome and Epidemiology Study). Muscle and fat mass were measured using multifrequency bioelectrical impedance analysis. The study endpoint was incident CKD (estimated glomerular filtration rate <60 mL/min/1.73 m² in at least two or more consecutive measurements during the follow-up period).

RESULTS

Totally, 7682 participants were evaluated. Their mean age was 51.7 ± 8.7 years, and 48% of the subjects were men. During a median follow-up of 140.0 (70.0-143.0) months, 633 (8.2%) subjects developed incident CKD. When the association between body composition and incident CKD was investigated, multivariable Cox proportional hazard analysis revealed that increase in MF ratio was related with a decreased risk of CKD development [per 1 increase in MF ratio: hazard ratio (HR), 0.86; 95% confidence interval (CI), 0.77-0.96; P = 0.008]. This association was also maintained when MF ratio was dichotomized according to sex-specific median values (high vs. low: HR, 0.83; 95% CI, 0.70-0.98; P = 0.031). Analyses preformed in a propensity score matched group also revealed a similar decreased risk of incident CKD in high MF ratio participants (high vs. low: HR, 0.84; 95% CI, 0.71-0.98; P = 0.037). This relationship between MF ratio and incident CKD risk was consistently significant across subgroups stratified by age, sex, hypertension, estimated glomerular filtration rate categories, and proteinuria. Among different BMI groups (normal, overweight, and obese), the relationship between high MF ratio and lower incident CKD risk was significant only in overweight and obese subjects.

CONCLUSIONS

Lower fat mass relative to muscle mass may lower the risk of CKD development in individuals with normal renal function. This relationship seems more prominent in overweight and obese subjects than in normal weight subjects.

P0926ASSOCIATION OF HIGH-SENSITIVE C-REACTIVE PROTEIN WITH CARDIOVASCULAR EVENTS, MORTALITY, AND ADVERSE KIDNEY OUTCOMES IN KOREAN PATIENTS WITH CHRONIC KIDNEY DISEASE: RESULTS FROM KNOW-CKD

Background and Aims

High-sensitivity C-reactive protein (hs-CRP) level is lower in East Asians than in the Western people and its clinical significance needs to be further explored. We aimed to investigate whether hs-CRP could function as a biomarker in Korean CKD patients.

Method

We studied the association of hs-CRP with adverse clinical outcomes in 2,018 patients from the KoreaN cohort study for Outcome in patients With Chronic Kidney Disease (KNOW-CKD). The primary outcome was a composite of extended major cardiovascular events (MACE) or all-cause mortality. Extended MACE (eMACE) included non-fatal cardiovascular events, symptomatic arrhythmia, and cardiac death. The secondary endpoints were separate outcome of eMACE, all-cause death, and adverse kidney outcome. We also evaluated predictive ability of hs-CRP for the primary outcome.

Results

The median hs-CRP level was 0.60 mg/L (IQR 0.2-1.7), and the mean eGFR was 53.6 ml/min/1.73 m2. During the mean follow-up of 3.9 years, there were 125 (6.2%) eMACEs and 80 (4.0%) deaths. The primary composite outcome occurred more frequently in patients with higher hs-CRP level than in those with lower hs-CRP level. In multivariable Cox analysis after adjustment of confounders, there was a graded association of hs-CRP with the primary outcome. The HRs (95% CI) for hs-CRP of 1.0 to 2.99, and ≥ 3.0 mg/L were 1.37 (0.89-2.12) and 2.20 (1.36-3.56), compared with

hs-CRP of &lt;1.0 mg/L. In analyses of secondary outcomes, this association was consistent for eMACE and all-cause death; however, hs-CRP was not associated with adverse kidney outcomes. Finally, prediction models failed to show improvement of predictive performance of hs-CRP compared to conventional factors.

Conclusion

In Korean CKD patients, serum hs-CRP level was low and significantly associated with higher risk of eMACEs and mortality. However, a low serum hs-CRP level was not predictive of adverse kidney outcome, and the predictive performance of hs-CRP was not strong.

Septicemia, necrotizing fasciitis, and peritonitis due to Vibrio vulnificus treated with early use of polymyxin B hemoperfusion in a patient undergoing CAPD: a case report

Background

Vibrio vulnificus infection is a rare but fatal foodborne illness. Here, we report a case of Vibrio vulnificus peritonitis followed by severe septicemia in a patient undergoing continuous ambulatory peritoneal dialysis (CAPD) who was treated with hemoperfusion using polymyxin B immobilized fiber.

Case presentation

A 63-year-old man undergoing CAPD was admitted to the emergency room due to general weakness, fever, and abdominal pain with hazy dialysate. Two days before admission, he had eaten raw fish. Initial laboratory tests including peritoneal fluid analysis suggested peritonitis. Despite empirical intraperitoneal antibiotic treatment, his fever did not subside, and multiple vesicles on the extremities newly appeared. The result of initial peritoneal fluid culture and blood cultures reported Vibrio vulnificus as the most likely causative pathogen. Hemoperfusion with polymyxin B immobilized fiber was performed to control gram-negative bacterial septicemia with antibiotics targeting the pathogenic organism. The patient recovered completely and was discharged without complications.

Discussion and conclusion

Suspicion of Vibrio vulnificus infection in susceptible immunocompromised patients is important for early diagnosis and prompt management. Peritonitis should be noted as a clinical manifestation of Vibrio vulnificus infection in CAPD patients, and polymyxin B hemoperfusion along with proper antibiotics could be considered as a treatment option.

Intensity of statin therapy and renal outcome in chronic kidney disease: Results from the Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease

Background

Higher statin intensity is associated with a lower risk of mortality in patients with cardiovascular disease. However, little is known about the relationship between statin intensity and chronic kidney disease (CKD) progression.

Methods

We studied whether statin intensity affects kidney function decline in 1,073 patients from the Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease. The participants were classified based on statin intensity as low, moderate, and high. The study endpoint was CKD progression (composite of doubling of serum creatinine, ≥ 50% decrease in estimated glomerular filtration rate [eGFR] from baseline, or end-stage renal disease).

Results

The mean age was 56.0 ± 11.4 years, and 665 (62.0%) participants were male. The mean eGFR was 51.7 ± 26.7 mL/min/1.73 m²; there were no differences in baseline eGFR among statin intensity groups. During the median follow-up of 39.9 (25.4-61.6) months, 255 (23.8%) patients reached the study endpoint. In multivariable Cox model after adjustment of confounders, the hazard ratios (95% confidence interval) for adverse kidney outcome were 0.97 (0.72-1.30) and 1.15 (0.60-2.20) in moderate and high statin intensity groups, respectively, compared with the low intensity group. In addition, no significant association was observed in subgroups stratified by age, sex, eGFR, and atherosclerotic cardiovascular disease risk scores.

Conclusion

We did not observe any significant association between intensity of statin therapy and progression of CKD. Long-term kidney outcomes may not be affected by statin intensity.

Efficacy and Safety of a Balanced Salt Solution Versus a 0.9% Saline Infusion for the Prevention of Contrast-Induced Acute Kidney Injury After Contrast-Enhanced Computed Tomography

Rationale & Objective

We aimed to elucidate whether a balanced salt solution decreases the occurrence of contrast-induced acute kidney injury (CI-AKI) after contrast-enhanced computed tomography (CE-CT) as compared to 0.9% saline solution.

Study Design

A randomized clinical trial.

Setting & Participants

The study was performed in 14 tertiary hospitals in South Korea. Patients with estimated glomerular filtration rates (eGFRs) < 45 or <60 mL/min/1.73 m² and additional risk factors (age ≥ 60 years or diabetes) who were undergoing scheduled CE-CT were included from December 2016 to December 2018.

Intervention

An open-label intervention was performed. The study group received a balanced salt solution and the control group received 0.9% saline solution as prophylactic fluids for CE-CT.

Outcomes

The primary outcome was CI-AKI, defined by creatinine level elevation ≥ 0.5 mg/dL or 25% from baseline within 48 to 72 hours after CE-CT. Secondary outcomes included AKI defined based on the KDIGO (Kidney Disease: Improving Global Outcomes) guideline, eGFR changes, death, or requiring dialysis within 6 months after CE-CT.

Results

493 patients received the study fluids. The control and study groups included 251 and 242 patients, respectively. The occurrence of CI-AKI in the study (10 [4.2%]) and control (17 [6.8%]) groups was not significantly different (P = 0.27). No significant difference was present for the secondary outcomes; AKI by the KDIGO definition (study: 19 [7.9%], control: 27 [10.8%]; P = 0.33), death/dialysis (study: 11 [4.7%], control: 9 [3.7%]; P = 0.74), and eGFR changes (study: 0.1 ± 0.2 mg/dL, control: 0.3 ± 2.8 mg/dL; P = 0.69).

Limitations

This study failed to meet target enrollment.

Conclusions

The risk for CI-AKI was similar after administration of a balanced salt solution and after use of 0.9% saline solution during CE-CT in higher-risk patients.

Funding

This study was funded by CJ Healthcare (CS2015_0046).

Trial Registration

Registered at ClinicalTrials.gov with study number NCT02799368.

Alcohol Consumption and Progression of Chronic Kidney Disease: Results From the Korean Cohort Study for Outcome in Patients with Chronic Kidney Disease

OBJECTIVE

To assess the association of alcohol consumption with chronic kidney disease (CKD) progression in patients with CKD.

PATIENTS AND METHODS

The KoreaN cohort study for Outcome in patients with CKD (KNOW-CKD) is a prospective observational study that included detailed questionnaires regarding alcohol consumption. The 1883 individuals with CKD were enrolled from April 1, 2011, through February 28, 2016, and followed until May 31, 2017. Using a questionnaire, alcohol consumption pattern was classified according to the amount of alcohol per occasion (none, moderate, or binge) or drinking frequency (none, occasional, or regular). The primary endpoint was a composite of 50% or greater decline in estimated glomerular filtration rate (eGFR) from the baseline level or end-stage renal disease.

RESULTS

During a follow-up of 5555 person-years (median, 2.95 years), the primary outcome occurred in 419 patients. Unadjusted cause-specific hazards model showed that the risk of the primary outcome was lower in drinkers than in non-drinkers. However, a fully adjusted model including eGFR and proteinuria yielded a reverse association. Compared with non-drinking, regular and occasional binge drinking were associated with a 2.2-fold (95% CI, 1.38-3.46) and a 2.0-fold (95% CI, 1.33-2.98) higher risk of CKD progression, respectively. This association was particularly evident in patients who had decreased kidney function and proteinuria. There was a significant interaction between alcohol consumption and eGFR for CKD progression. The slopes of eGFR decline were steeper in binge drinkers among patients with eGFR less than 60 mL/min/1.73 m².

CONCLUSIONS

Heavy alcohol consumption was associated with faster progression of CKD.

Incidence of Acute Kidney Injury after Adrenalectomy in Patients with Primary Aldosteronism

Background

Aldosterone-induced glomerular hyperfiltration can lead to masked preoperative renal dysfunction in primary aldosteronism(PA) patients. We evaluated whether PA patients had a higher prevalence of acute kidney injury (AKI) after unilateral adrenalectomy. In addition, we identified risk factors for AKI in these subjects.

Methods

This retrospective study included 107 PA patients, and 186 pheochromocytoma patients as a control group, all of whom underwent adrenalectomy between January 2006 and November 2017 at Yonsei University Severance Hospital. The primary outcome was AKI within 48 hours after adrenalectomy. Univariate and multivariate logistic regression analyses were performed to identify predictors of AKI after adrenalectomy.

Results

Overall incidence of AKI was 49/293 (16.7%). In PA patients, the incidence of AKI was 29/107 (27.1%). In contrast, incidence of AKI was 20/186 (10.7%) in pheochromocytoma patients. Univariate and multivariate logistic regression analysis both showed a higher risk of postoperative AKI in PA patients compared to pheochromocytoma patients. In addition, old age, diabetes, longer duration of hypertension, lower preoperative estimated glomerular filtration rate, high aldosterone-cortisol ratio (ACR) and lateralization index (LI) were identified as independent risk factors for postoperative AKI in PA patients after unilateral adrenalectomy.

Conclusion

Incidence and risk of postoperative AKI were significantly higher in PA patients after surgical treatment. High ACR on the tumor side and high LI were associated with higher risk of AKI in PA patients compared to pheochromocytoma patients.

Continuous Renal Replacement Therapy (CRRT) in Children and the Specialized CRRT Team: A 14-Year Single-Center Study

Continuous renal replacement therapy (CRRT) has been used as an important intervention in critically ill children. Our center has the only specialized CRRT team (SCT) for children in Korea, which consists of pediatric intensivists, a pediatric nephrologist and CRRT-specialized-nurses. This study was a retrospective single-center analysis, including all pediatric patients admitted to the intensive care unit (ICU) of Severance hospital in Korea and received CRRT between 2003 and 2016, grouped as before SCT (group A, n = 51) and after SCT (group B, n = 212). We obtained the data for sex, age, weight, diagnosis, blood flow rate or type of CRRT machine used, administration of inotropic agents or anticoagulants, and ICU duration before CRRT (hours). A total of 263 patients were included. The age was significantly younger (p < 0.001) and blood flow rate was lower (p = 0.001) in group B than group A. Vasopressors (p < 0.001), continuous veno-venous hemodiafiltration (CVVHDF) (p < 0.001), nafamostat mesilate (p < 0.001), and extracorporeal membrane oxygenation (ECMO)-CRRT (p = 0.004) were more frequently used in group B. Based on our 14-year experience, we conclude that SCT operation could have played an important role in increasing the amount of CRRT utilization.

Lower serum beta-2 microglobulin levels are associated with worse survival in incident peritoneal dialysis patients

Background

There is a general consensus that elevated serum beta-2 microglobulin (B2M) levels measured at a single time-point are significantly associated with mortality in patients on maintenance dialysis. To date, the majority of prior studies that have examined B2M-associated mortality have been conducted in prevalent hemodialysis patients with little residual renal function (RRF). However, studies in incident peritoneal dialysis (PD) patients are lacking. Moreover, changes in serum B2M levels over time have not been considered in this population.

Methods

We examined the association of time-updated and baseline serum B2M levels with mortality in a 10-year cohort of 725 incident PD patients who were maintained on dialysis between January 2006 and December 2011 using Cox proportional hazards regression analyses. Patients were categorized into tertiles according to B2M levels.

Results

During a median follow-up of 38 (interquartile range 23-64) months, 258 (35.4%) deaths occurred, including 106 (14.6%) and 86 (11.9%) deaths from cardiovascular and infectious causes, respectively. The lowest B2M tertile was associated with a higher risk of all-cause and infectious mortality compared with the middle tertile: the hazard ratios (95% confidence interval) for all-cause deaths were 2.12 (1.38-3.26) and 2.20 (0.96-5.05) in time-varying analyses and 1.52 (1.07-2.17) and 2.41 (1.19-4.88) in baseline analyses. Subgroup analyses showed that this association was particularly observed in females, older patients, those with comorbidities such as diabetes, a lower body mass index, lower albumin levels or those with higher RRF (all P for interactions <0.05).

Conclusions

In incident PD patients, lower B2M levels were independently associated with overall and infectious mortality. These associations can be potentially modified by malnutrition, inflammation and RRF.

Safety and efficacy of PG102P for the control of pruritus in patients undergoing hemodialysis (SNUG trial): study protocol for a randomized controlled trial

BACKGROUND

Pruritus in patients undergoing hemodialysis is a highly prevalent complication that affects quality of life. Several medications are currently used for the treatment of uremic pruritus, but these are not satisfactory. PG102P, which is prepared from Actinidia arguta, has an immune-modulating effect on pruritus. This trial is designed to assess the antipruritic effect of PG102P compared with placebo.

METHODS

This multicenter, randomized, double-blind, placebo-controlled clinical trial will include 80 patients undergoing hemodialysis. The patients will be randomized in a 1:1 ratio to a treatment group (PG102P 1.5 g/day) or a control group (placebo). The treatment will last for 8 weeks, followed by a 2-week observational period. During the observational period, all of the patients will maintain the antipruritic treatment previously used. The primary endpoint will be measured as the difference in visual analog scale between the groups before and after treatment. Secondary outcomes include serum levels of total immunoglobulin E, eosinophil cationic protein, potassium, calcium, phosphorus, intact parathyroid hormone, and blood eosinophil count between weeks 0 and 8. Kidney Disease and Quality of Life and Beck's Depression Inventory questionnaires will be conducted. Safety assessments and any adverse events that occur will also be evaluated.

DISCUSSION

The SNUG is a clinical study that aims to investigate the antipruritic effect of PG102P to ameliorate itching in patients undergoing hemodialysis.

TRIAL REGISTRATION

Clinical Trials.gov, NCT03576235. Registered on 4 July 2018.

Budget Impact Analysis of the Change in Peritoneal Dialysis Use Rate in Korea

Background:While the number of peritoneal dialysis (PD) patients has decreased by 14.4% from 2006 to 2016, the number of hemodialysis (HD) patients has sharply increased, by 237.2%, in the same period, leading to an increase in the total medical cost. We analyzed the effects of the changes in PD use rates for dialysis patients in Korea on the healthcare budget using budget impact analysis (BIA).Methods:The analysis modeled the influence of the increase in dialysis for the target population, changes in modality use rate, and/or changes in costs per patient-year on total medical cost for patients on dialysis, using the National Health Insurance Service (NHI) claims data. We developed 8 scenarios according to the changing PD use rate.Results:In scenarios 1 - 4 (increase in PD patients by 6%, 13%, 20%, and 50% of non-diabetic prevalent HD patients under 65), 5-year budget savings ranged from $47 million to $394 million (0.9% - 7.3% of the end-stage renal disease [ESRD] budget). In scenarios 5 - 8 (increase in incident PD patients by 20%, 50%, 70%, and 100% of non-diabetic patients under 65), 5-year savings ranged from $25 million to $74 million (0.5% - 1.4% of the ESRD budget). In all scenarios, budget savings were higher as PD patients increased, showing a gradually growing trend.Conclusion:In all scenarios from the payer's perspective, savings could be achieved through an increase in PD use. Selecting PD for ESRD patients without different expected clinical outcomes between HD and PD would be beneficial to the NHI budget.

Urine Osmolality and Renal Outcome in Patients with Chronic Kidney Disease: Results from the KNOW-CKD

BACKGROUND

Urine osmolality indicates the ability of the kidney to concentrate the urine and reflects the antidiuretic action of vasopressin. However, results about the association between urine osmolality and adverse renal outcomes in chronic kidney disease (CKD) are conflicting. We investigated the association between urine osmolality and adverse renal outcomes in a nationwide prospective CKD cohort.

METHODS

A total of 1,999 CKD patients were categorized into 3 groups according to their urine osmolality tertiles. Primary outcome was a composite of 50% decline in the estimated glomerular filtration rate (eGFR), initiation of dialysis, or kidney transplantation.

RESULTS

During a mean follow-up of 35.2 ± 19.0 months, primary outcome occurred in 432 (21.6%) patients; 240 (36.4%), 162 (24.3%), and 30 (4.5%) in the lowest, middle, and highest tertiles, respectively. Low urine osmolality was independently associated with a greater risk of CKD progression (hazard ratio [HR], 1.71; 95% confidence interval [CI], 1.12-2.59). This association was particularly evident in patients with CKD stages 3-4 (per 10 mosm/kg decrease; HR, 1.02; 95% CI, 1.00-1.03). Adding urine osmolality to a base model with conventional factors significantly increased the ability to predict CKD progression (C-statistics, 0.86; integrated discrimination improvement [IDI], 0.021; both p < 0.001). However, adding both urine osmolality and eGFR did not further improve the predictive ability compared with the addition of eGFR only (C-statistics, p = 0.29; IDI, p = 0.09).

CONCLUSIONS

Low urine osmolality was an independent risk factor for adverse renal outcomes in CKD patients, but its predictive ability did not surpass eGFR. Thus, kidney function should be considered while interpreting the clinical significance of urine osmolality.

Prediction model development of late-onset preeclampsia using machine learning-based methods

Preeclampsia is one of the leading causes of maternal and fetal morbidity and mortality. Due to the lack of effective preventive measures, its prediction is essential to its prompt management. This study aimed to develop models using machine learning to predict late-onset preeclampsia using hospital electronic medical record data. The performance of the machine learning based models and models using conventional statistical methods were also compared. A total of 11,006 pregnant women who received antenatal care at Yonsei University Hospital were included. Maternal data were retrieved from electronic medical records during the early second trimester to 34 weeks. The prediction outcome was late-onset preeclampsia occurrence after 34 weeks’ gestation. Pattern recognition and cluster analysis were used to select the parameters included in the prediction models. Logistic regression, decision tree model, naïve Bayes classification, support vector machine, random forest algorithm, and stochastic gradient boosting method were used to construct the prediction models. C-statistics was used to assess the performance of each model. The overall preeclampsia development rate was 4.7% (474 patients). Systolic blood pressure, serum blood urea nitrogen and creatinine levels, platelet counts, serum potassium level, white blood cell count, serum calcium level, and urinary protein were the most influential variables included in the prediction models. C-statistics for the decision tree model, naïve Bayes classification, support vector machine, random forest algorithm, stochastic gradient boosting method, and logistic regression models were 0.857, 0.776, 0.573, 0.894, 0.924, and 0.806, respectively. The stochastic gradient boosting model had the best prediction performance with an accuracy and false positive rate of 0.973 and 0.009, respectively. The combined use of maternal factors and common antenatal laboratory data of the early second trimester through early third trimester could effectively predict late-onset preeclampsia using machine learning algorithms. Future prospective studies are needed to verify the clinical applicability algorithms.

The Association of Glomerular Glucocorticoid Receptor Expression with Responsiveness to Corticosteroid Treatment in IgA Nephropathy

BACKGROUND

Corticosteroids can be used to treat IgA nephropathy (IgAN). However, responsiveness to these drugs is highly variable and unpredictable. Corticosteroids act by binding glucocorticoid receptors (GCRs). Therefore, we evaluated the association between GCR expression and responsiveness to corticosteroid treatment in IgAN.

METHODS

We screened 78 IgAN patients receiving steroid treatment between 2010 and 2016. Of these, 33 patients met study inclusion criteria. Glomerular GCR expression was assessed by real-time polymerase chain reaction. Complete remission (CR) and partial remission (PR) were defined as a spot urine protein-to-creatinine ratio (UPCR) of <0.3 g/g and a ≥50% reduction of proteinuria from baseline along with UPCR of ≥0.3 g/g, respectively. Disease progression was defined as a ≥30% decrease in estimated glomerular filtration rate (eGFR) from baseline.

RESULTS

The mean age of study patients was 43.9 ± 11.6 years (25 males and 8 females). All 33 patients responded to steroid treatment; CR and PR occurred in 14 (42.4%) and 18 (54.5%) patients, respectively. One patient did not achieve PR, but proteinuria was decreased after treatment. There were no significant differences in baseline eGFR and proteinuria between CR and non-CR groups. GCR mRNA expression was significantly higher in the CR group compared to that in the non-CR group. Immunohistochemistry confirmed higher GCR expression in the CR group. During a median follow-up of 20.6 months, 1 (7.1%) patient in the CR group had disease progression, as compared to 8 (42.1%) patients in non-CR group (p = 0.03).

CONCLUSION

This study suggests that responsiveness to corticosteroid may differ depending on the degree of glomerular GCR expression in IgAN.

Snoring and incident chronic kidney disease: a community-based prospective cohort study

OBJECTIVES

Previous studies have shown that symptoms of sleep-disordered breathing are associated with metabolic derangements and vascular disease development. However, the relationship between snoring and renal function is not well investigated. The association between snoring and the development of incident chronic kidney disease (CKD) in subjects with normal renal function was evaluated.

DESIGN

Prospective cohort study.

SETTING

Ansung (rural community) and Ansan (urban community) cities.

PARTICIPANTS

Community-based cohort participants aged 40-69 years.

METHODS

A total of 9062 participants in the Ansung-Ansan cohort study were prospectively followed up from 2001 to 2014. The participants were classified into three groups: non-snorer, <1 day/week and ≥1 day/week. The main outcome was incident CKD, which was defined as an estimated glomerular filtration rate of <60 mL/min/1.73 m² during the follow-up period.

PRIMARY OUTCOME

Incident CKD.

RESULTS

The mean subject age was 52.0±8.9 years, and 4372 (48.2%) subjects were male. The non-snorer,<1 day/week and ≥1 day/week groups included 3493 (38.5%), 3749 (41.4%), and 1820 (20.1%) subjects, respectively. Metabolic syndrome was more prevalent in the snoring groups than in the non-snoring group. Snoring frequency showed a significant positive relationship with age, waist:hip ratio, fasting glucose, total cholesterol (Tchol) and low-density lipoprotein cholesterol. During a mean follow-up of 8.9 years, 764 (8.4%) subjects developed CKD. Cox proportional hazards model analysis revealed that the risk of CKD development was significantly higher in subjects who snored ≥1 day/week than in non-snorers, even after adjustments for confounding factors (HR 1.23, 95% CI 1.09 to 1.38, p<0.01).

CONCLUSION

Snoring may increase the risk of CKD development in subjects with normal renal function.

Anisotropic spin fluctuations in detwinned FeSe

Superconductivity in FeSe emerges from a nematic phase that breaks four-fold rotational symmetry in the iron plane. This phase may arise from orbital ordering, spin fluctuations or hidden magnetic quadrupolar order. Here we use inelastic neutron scattering on a mosaic of single crystals of FeSe, detwinned by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are most intense at the antiferromagnetic wave vectors QAF = (±1, 0) at low energies E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies, 3-5 meV, indicating a gapped four-fold (C4) mode. In the superconducting state, however, the strong nematic anisotropy is again reflected in the spin resonance (E = 3.6 meV) at QAF with incommensurate scattering around 5-6 meV. Our results highlight the extreme electronic anisotropy of the nematic phase of FeSe and are consistent with a highly anisotropic superconducting gap driven by spin fluctuations.

High-protein diet with renal hyperfiltration is associated with rapid decline rate of renal function: a community-based prospective cohort study

Background

The effect of a high-protein diet with renal hyperfiltration (RHF) on decline of kidney function has rarely been explored. We investigated the association between a high-protein diet, RHF and declining kidney function.

Methods

A total of 9226 subjects from the Korean Genome and Epidemiology Study, a community-based prospective study (2001–14), were enrolled and classified into quartiles according to daily amount of protein intake based on food frequency questionnaires. RHF was defined as estimated glomerular filtration rate (eGFR) with residuals of >95th percentile after adjustment for age, sex, history of hypertension or diabetes, height and weight. Rapid decline of renal function was defined as decline rate of eGFR >3 mL/min/1.73 m2/year.

Results

The relative risk of RHF was 3.48-fold higher in the highest than in the lowest protein intake quartile after adjustment for confounding factors [95% confidence interval (CI) 1.39–8.71]. The mean eGFR decline rate was faster as quartiles of protein intake increased. Furthermore, the highest quartile was associated with 1.32-fold increased risk of rapid eGFR decline (95% CI 1.02–1.73). When subjects were divided into two groups with or without RHF, the highest quartile was associated with a rapid decline in renal function only in RHF subjects (odds ratio 3.35; 95% CI 1.07–10.51). The sensitivity analysis using the Korean National Health and Nutrition Examination Survey (2008–15) data with 40 113 subjects showed that higher quartile was associated with increased risk for RHF.

Conclusions

A high-protein diet increases the risk of RHF and a rapid renal function decline in the general population. These findings suggest that a high-protein diet has a deleterious effect on renal function in the general population.