Importance of glomerular filtration rate change as surrogate endpoint for the future incidence of end-stage renal disease in general Japanese population: community-based cohort study

Changes in estimated glomerular filtration rate in patients administered proton pump inhibitors: a single-center cohort study

Proton pump inhibitor (PPI) use may be associated with renal dysfunction. Renal dysfunction in PPI users requires evaluation of development and progression risks simultaneously, using estimated glomerular filtration rate (eGFR) slope, which indicates changes in eGFR per year. To the best of our knowledge, no studies have evaluated eGFR slope in PPI users. This study investigated the association between PPI use and renal dysfunction using eGFR slope. A single-center cohort study was conducted using the health records data at Hamamatsu University Hospital in Japan. Participants were defined as first users of acid-suppressing drugs (PPIs or Histamine H2 receptor antagonists (H2RAs)) from 2010 to 2021 and continuously prescribed for  ≥ 90 days. The H2RA group was used for the propensity-score matching (PSM) to the PPI group to minimize the effects of confounders. The eGFR slope was estimated using a linear mixed effects model. Participants were stratified by baseline eGFR and age, respectively, as subgroup analyses. A total of 4,649 acid-suppressing drug users met the inclusion criteria, including 950 taking H2RAs and 3,699 PPIs. After PSM, 911 patients were assigned to each group. The eGFR slopes of the PPI and H2RA users were -4.75 (95% CI: -6.29, -3.20) and -3.40 (-4.38, -2.42), respectively. The difference between the groups was not significant. Significant declines in eGFR were observed with PPIs with baseline eGFR ≥ 90 and age  < 65. PPI use for  ≥ 90 days may hasten eGFR decline compared to H2RA use, especially in patients with eGFR  ≥ 90 or age  < 65.

Characterization of baseline clinical factors associated with incident worsening kidney function in patients with non-valvular atrial fibrillation: the Hokuriku-Plus AF Registry

Evidence suggests that atrial fibrillation (AF) could increase the risk of worsening kidney function (WKF) which is linked to an increased risk of stroke, bleeding, and death in AF patients. However, limited data exist regarding the factors that could lead to WKF in these patients. Therefore, we sought to identify the potential factors associated with the development of WKF in patients with non-valvular AF (NVAF). We analyzed prospectively recruited 1122 NVAF patients [men 71.9%, median age 73.0 years (interquartile range: 66.0-79.0)] with a baseline estimated glomerular filtration rate (eGFR) ≥ 15 mL/min/1.73 m² from the Hokuriku-Plus AF Registry. The primary outcome was incident WKF, defined as the %eGFR change from the baseline ≥ 30% during the follow-up period. We evaluated the association between baseline variables and incident WKF using univariate and multivariate Cox proportional hazard models. We also evaluated the non-linear association between the identified factors and incident WKF. During a median follow-up period of 3.0 years (interquartile range: 2.7-3.3), incident WKF was observed in 108 patients (32.6 per 1000 person-years). Compared to the patients without incident WKF, the patients with incident WKF were older and had a higher prevalence of heart failure (HF), diabetes mellitus (DM), and vascular disease at baseline. Those who experienced incident WKF also had higher diastolic blood pressure, lower hemoglobin, lower eGFR, higher B-type natriuretic peptide (BNP) and used warfarin more frequently. Upon multivariate analysis, age ≥ 75 years, HF, DM, and anemia were independently associated with incident WKF. Additionally, age and hemoglobin were linearly associated with the risk of incident WKF, whereas a J- or U-shaped association was observed for HbA1c and BNP. Age ≥ 75 years, HF, DM, and anemia were associated with the development of WKF in Japanese patients with NVAF. In patients with these risk factors, a careful monitoring of the kidney function and appropriate interventions may be important when possible.

Incidence of acute kidney injury and decreased estimated glomerular filtration rate according to the site of cancer

BACKGROUND

The epidemiology of renal impairment in patients with cancer remains unclear. We aimed to clarify associations between various cancer sites and renal impairment.

METHODS

We reviewed data from 5674 patients aged ≥ 18 years receiving cancer treatment at a single hospital facility. The primary endpoints were the occurrence of acute kidney injury (AKI), a 30% decrease in the estimated glomerular filtration rate (eGFR), or death. Survival time was defined as the time from study enrolment to AKI occurrence. Kaplan-Meier and Cox proportional hazard analyses were performed.

RESULTS

Hazard ratios (HRs) for AKI occurrence and a ≥ 30% decline in eGFR were significantly higher for kidney, urinary tract, pancreatic, liver, and gallbladder cancers than for colon cancer. Compared with colon cancer, digestive tract cancer showed a significantly higher HR for AKI occurrence alone. The HRs for a ≥ 30% decline in eGFR were significantly higher for patients aged 71‒77 years or ≥ 78 years than for those aged < 68 years, and for patients with eGFR ≥ 90 mL/min/1.73 m² or 30-44 mL/min/1.73 m² than for those with eGFR = 45‒59 mL/min/1.73 m².

CONCLUSIONS

Kidney, urinary, hepatobiliary, or pancreatic cancer are associated with a higher risk of AKI development and eGFR decrease than other cancers. Renal function changes should be more closely monitored in patients with these cancers.

Potential progression biomarkers of diabetic kidney disease determined using comprehensive machine learning analysis of non-targeted metabolomics

Diabetic kidney disease is the main cause of end-stage renal disease worldwide. The prediction of the clinical course of patients with diabetic kidney disease remains difficult, despite the identification of potential biomarkers; therefore, novel biomarkers are needed to predict the progression of the disease. We conducted non-targeted metabolomics using plasma and urine of patients with diabetic kidney disease whose estimated glomerular filtration rate was between 30 and 60 mL/min/1.73 m². We analyzed how the estimated glomerular filtration rate changed over time (up to 30 months) to detect rapid decliners of kidney function. Conventional logistic analysis suggested that only one metabolite, urinary 1-methylpyridin-1-ium (NMP), was a promising biomarker. We then applied a deep learning method to identify potential biomarkers and physiological parameters to predict the progression of diabetic kidney disease in an explainable manner. We narrowed down 3388 variables to 50 using the deep learning method and conducted two regression models, piecewise linear and handcrafted linear regression, both of which examined the utility of biomarker combinations. Our analysis, based on the deep learning method, identified systolic blood pressure and urinary albumin-to-creatinine ratio, six identified metabolites, and three unidentified metabolites including urinary NMP, as potential biomarkers. This research suggests that the machine learning method can detect potential biomarkers that could otherwise escape identification using the conventional statistical method.

Nomogram to predict rapid kidney function decline in population at risk of cardiovascular disease

BACKGROUND

To develop a reliable model to predict rapid kidney function decline (RKFD) among population at risk of cardiovascular disease.

METHODS

In this retrospective study, key monitoring residents including the elderly, and patients with hypertension or diabetes of China National Basic Public Health Service who underwent community annual physical examinations from January 2015 to December 2020 were included. Healthy records were extracted from regional chronic disease management platform. RKFD was defined as the reduction of estimated glomerular filtration rate (eGFR) ≥ 40% during follow-up period. The entire cohort were randomly assigned to a development cohort and a validation cohort in a 2:1 ratio. Cox regression analysis was used to identify the independent predictors. A nomogram was established based on the development cohort. The concordance index (C-index) and calibration plots were calculated. Decision curve analysis was applied to evaluate the clinical utility.

RESULTS

A total of 8455 subjects were included. During the median follow-up period of 3.72 years, the incidence of RKFD was 11.96% (n = 1011), 11.98% (n = 676) and 11.92% (n = 335) in the entire cohort, development cohort and validation cohort, respectively. Age, eGFR, hemoglobin, systolic blood pressure, and diabetes were identified as predictors for RKFD. Good discriminating performance was observed in both the development (C-index, 0.73) and the validation (C-index, 0.71) cohorts, and the AUCs for predicting 5-years RKFD was 0.763 and 0.740 in the development and the validation cohort, respectively. Decision curve analysis further confirmed the clinical utility of the nomogram.

CONCLUSIONS

Our nomogram based on five readily accessible variables (age, eGFR, hemoglobin, systolic blood pressure, and diabetes) is a useful tool to identify high risk patients for RKFD among population at risk of cardiovascular disease in primary care. Whereas, further external validations are needed before clinical generalization.

A Long-term Estimated Glomerular Filtration Rate Plot Analysis Permits the Accurate Assessment of a Decline in the Renal Function by Minimizing the Influence of Estimated Glomerular Filtration Rate Fluctuations

Objective Evaluating the rate of decline in the estimated glomerular filtration rate (eGFR) may help identify patients with occult chronic kidney disease (CKD). We herein report that eGFR fluctuation complicates the assessment of the rate of decline and propose a long-term eGFR plot analysis as a solution. Methods In 142 patients with persistent eGFR decline in a single hospital, we evaluated the factors influencing the rate of eGFR decline, calculated over the long term (≥3 years) and short term (<3 years) using eGFR plots, taking into account eGFR fluctuation between visits. Results The difference between the rate of eGFR decline calculated using short- and long-term plots increased as the time period considered in the short-term plots became shorter. A regression analysis revealed that eGFR fluctuation was the only factor that explained the difference and that the fluctuation exceeded the annual eGFR decline in all participants. Furthermore, the larger the eGFR fluctuation, the more difficult it became to detect eGFR decline using a short-term eGFR analysis. Obesity, a high eGFR at baseline, and faster eGFR decline were associated with larger eGFR fluctuations. To circumvent the issue of eGFR fluctuation in the assessment of the rate of eGFR decline, we developed a system that generates a long-term eGFR plot using all eGFR values for a participant, which enabled the detection of occult CKD, facilitating early therapeutic intervention. Conclusion The construction of long-term eGFR plots is useful for identifying patients with progressive eGFR decline, as it minimizes the effect of eGFR fluctuation.

Association between circulating microRNAs and changes in kidney function: A five-year prospective study among Japanese adults without CKD

BACKGROUND

Although a number of microRNAs (miRNA) reflecting kidney function has been identified, prospective studies are now urgently needed to determine a clinical utility of these miRNAs among general populations. The purpose of this study was to examine the associations between serum miRNAs and kidney function in a population-based study.

METHODS

We conducted a five-year prospective study (2012-2017) of 169 individuals without chronic kidney disease (CKD) at the baseline survey (mean age, 62.5; 96 women). The real-time qPCR was used to measure serum levels of five previously reported miRNAs. Participants with eGFR < 60 mL/min/1.73 m² were defined as having CKD. Changes in eGFR were defined as eGFR₂₀₁₇ - eGFR₂₀₁₂.

RESULTS

After adjusting for covariates including baseline eGFR, lower serum levels (1st tertile) of miR-126 were associated with a greater decline of eGFR (β [SE] = -3.18 [1.50]) and a higher odds ratio (OR) of CKD onset over five years (OR [95% CI] = 3.85 [1.01-16.8]), compared with the 3rd tertile.

CONCLUSIONS

We found baseline serum miR-126 levels were associated with changes in eGFR and new CKD cases in a five-year prospective study. This result suggests that miR-126 may be a potential biomarker of CKD even among general populations.

Long-term continuous use of proton-pump inhibitors is associated with renal function decline in patients without acute kidney injury

BACKGROUND

Proton-pump inhibitors (PPIs) are widely used to treat gastroesophageal reflex disease, peptic ulcer disease, and stress ulcer prophylaxis. This study estimated the progress rate of renal dysfunction in patients taking PPIs in clinical settings and compared the results with those of patients taking histamine-2 receptor antagonists (H2RAs).

METHODS

We retrospectively reviewed patients' data collected from Kochi Medical School Hospital's information system between 2001 and 2019. Patients were classified into PPI and H2RA groups, and survival time was defined as the period between initial drug administration and a 30% decrease in estimated glomerular filtration rate (eGFR).

RESULTS

On survival analysis, the PPI group was associated with higher event incidence rates compared to that in the H2RA group. The rate of underlying disease was significantly higher in the PPI group than in the H2RA group, with no significant differences in age and sex between the groups. Comparing the PPI group to the H2RA group, the use of aspirin, clopidogrel, statin, and angiotensin II receptor blocker was significantly higher, whereas the use of non-steroidal anti-inflammatory drugs and steroids was significantly less. Regarding survival rate and 30% decrease in eGFR, the PPI group had a significantly higher survival rate compared to that in the H2RA group at 730 days, but not earlier. PPI use, older age, and eGFR ≥ 90 mL/min/1.73 m² exhibited high hazard ratios.

CONCLUSIONS

PPI use was significantly associated with an increased risk of chronic kidney disease development compared to that with H2RA use.

Utility of remission criteria for the renal prognosis of IgA nephropathy

Background

Novel criteria for the remission of Immunoglobulin A nephropathy (IgAN) based on an opinion survey of Japanese nephrologists and literature review were proposed in 2013. This single-center, longitudinal retrospective cohort study was conducted to validate this criteria.

Methods

Present study included the IgAN patients diagnosed between 2001 and 2005 in the Juntendo University Hospital. Remission of hematuria was defined as three consecutive dipstick test results of ( −) to ( ±) or a red blood cell count < 5 in urinary sediment per high-power field during at least 6 months. Remission of proteinuria was defined as three consecutive dipstick results of ( −) to ( ±) during at least 6 months. We categorized four groups according to the remission status which was assessed 2 years after the renal biopsy. The primary outcome was a 50% increase in the serum creatinine over the baseline. We evaluated the slope of eGFR decline (mL/min/1.73 m²/year) and a decrease in the eGFR of 30% from baseline eGFR as the secondary outcome, respectively.

Results

A total of 74 patients (male: 47.3%, median age: 30 years) were included and were followed for a median of 86.5 months. During the period, forty-one patients achieved neither remission of proteinuria nor hematuria (NR). Twelve patients met the primary study outcome. A survival analysis revealed that the NR had the worst prognosis and the steepest slope of eGFR decline.

Conclusion

Although further validation in a large cohort is necessary, these novel remission criteria for IgAN patients appear to predict the renal prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10157-021-02069-w.

Stages of a transtheoretical model as predictors for the decline of estimated glomerular filtration rate: a retrospective cohort study

Background

The transtheoretical model (TTM) is composed of the multiple stages according to patient’s consciousness and is believed to lead people to realize the importance of healthier behaviors. We examined the association of TTM stages with the decline of estimated glomerular filtration rate (eGFR).

Methods

We used the annual health checkup data and health insurance claims data of the Japan Health Insurance Association in Kyoto Prefecture between April 2012 and March 2016. TTM stages of change obtained from questionnaires at the first health checkup and categorized into six groups. The primary outcome was defined as a more than 30% decline in eGFR from the first health checkup. We fitted multivariable Cox proportional-hazards model for time-to-event analyses adjusting for age, sex, eGFR, body mass index, blood pressure, blood sugar, dyslipidemia, uric acid, urinary protein, and existence of kidney diseases at first health checkup.

Results

We analyzed 239,755 employees and the mean follow-up was 2.9 (standard deviation, 1.2) years. As compared with the stage 1 group, the risk of eGFR decline was significantly low in the stage 3 group (hazard ratio [HR] 0.77; 95% confidence interval [CI], 0.65–0.91); stage 4 group (HR 0.80; 95% CI, 0.65–0.98); and stage 5 group (HR 0.79; 95% CI, 0.66–0.95).

Conclusion

Compared with the precontemplation stage (stage 1), the preparation, action and maintenance stages (stages 3, 4, and 5), were associated with a lower risk of eGFR decline.

Age differences in the relationships between risk factors and loss of kidney function: a general population cohort study

BACKGROUND

Annual decline in kidney function is a widely applied surrogate outcome of renal failure. It is important to understand the relationships between known risk factors and the annual decline in estimated glomerular filtration rate (eGFR) according to baseline age; however, these remain unclear.

METHODS

A community-based retrospective cohort study of adults who underwent annual medical examinations between 1999 and 2013 was conducted. The participants were stratified into different age groups (40-49, 50-59, 60-69, 70-79, and ≥ 80 years) to assess the risk for loss of kidney function. A mixed-effects model was used to estimate the association between risk factors and annual changes in eGFR.

RESULTS

In total, 51,938 participants were included in the analysis. The age group of ≥80 years included 8127 individuals. The mean annual change in eGFR was - 0.39 (95% confidence interval: - 0.41 to - 0.37) mL/min/1.73 m² per year. Older age was related to faster loss of kidney function. In the older age group, higher systolic blood pressure, proteinuria, and current smoking were related to faster loss of kidney function (p trend < 0.01, 0.03, and < 0.01, respectively). Conversely, each age group showed similar annual loss of kidney function related to lower hemoglobin levels and diabetes mellitus (p trend 0.47 and 0.17, respectively).

CONCLUSIONS

Higher systolic blood pressure, proteinuria, and smoking were related to faster loss of kidney function, and a greater effect size was observed in the older participants. More risk assessments for older people are required for personalized care.

GFR slope as a surrogate endpoint for CKD progression in clinical trials

PURPOSE OF REVIEW

There is a paucity of therapies for chronic kidney disease (CKD), in part because of the slow nature of the disease which poses challenges in selection of endpoints in randomized controlled trials (RCT). There is increasing evidence for the use of glomerular filtration rate (GFR)-based endpoints either as percentage decline using time-to-event analyses, or as difference in slope between treatment arms. We reviewed the rationale for using surrogate endpoints and optimal methods for their evaluation prior to their use and evidence for GFR-based endpoints and particularly GFR slope as validated surrogate endpoints and considerations for their use in RCTs.

RECENT FINDINGS

In an individual patient meta-analysis of 47 studies (60 620 participants), treatment effects on the clinical endpoint were accurately predicted from treatment effects on 3-year total slope [median R = 0.97 (95% Bayesian confidence interval (BCI), 0.78-1.00] and on the chronic slope [R = 0.96 (95% BCI, 0.63-1.00)]. In a simulation study, GFR slope substantially reduced the required sample size and duration of follow-up compared to the clinical endpoint given high baseline GFR and absence of acute treatment effect. In the presence of acute effect, results were more complicated.

SUMMARY

GFR decline is accepted, and GFR slope is being considered, by regulatory authorities as a validated surrogate endpoint for CKD RCTs.

Risk of Renal Function Decline in Patients with Ketamine-Associated Uropathy

Ketamine-associated diseases have been increasing with the rise in ketamine abuse. Ketamine-associated uropathy is one of the most common complications. We investigated the effects of ketamine-associated uropathy on renal health and determined predictors of renal function decline in chronic ketamine abusers. This retrospective cohort study analyzed 51 patients (22 with ketamine-associated hydronephrosis and 29 with ketamine cystitis) from Kaohsiung Veterans General Hospital in Taiwan. Primary renal outcome was end-stage renal disease or estimated glomerular filtration rate decline >30% from baseline. Compared with the ketamine cystitis group, the hydronephrosis group had lower initial and final estimated glomerular filtration rates and higher alkaline phosphatase and gamma-glutamyl transferase levels (p < 0.05). Elevated cholestatic liver enzyme levels correlated with renal dysfunction in ketamine-associated uropathy. The hydronephrosis group had a higher proportion of patients reaching endpoints than the ketamine cystitis group (50% and 7%, respectively, p < 0.001). After adjusting for age, sex, and initial serum creatinine level, hydronephrosis remained an independent risk factor for renal function deterioration. Ketamine-associated hydronephrosis was a poor renal outcome and strong predictor of renal function decline in chronic ketamine abusers. Elevated cholestatic liver enzyme levels correlated with the severity of ketamine-associated uropathy. Ultrasonography screening of these high-risk groups and regular renal function follow-ups are necessary.

The effects of Benson relaxation technique on activities of daily living in hemodialysis patients; A single-blind, randomized, parallel-group, controlled trial study

BACKGROUND AND PURPOSE

Many patients with renal failure due to the chronic nature of the disease and prolonged dialysis treatment experience dramatically reduced ability to perform daily living activities (ADLs). This study was aimed at evaluating the effects of Benson relaxation technique (BRT) on ADLs in hemodialysis (HD) patients.

MATERIALS AND METHODS

This single-blind, randomized, parallel-group, controlled trial study was conducted among 65 hemodialysis patients. They were randomly divided into intervention (n = 33) and control (n = 32) groups. In the intervention group, BRT was performed twice daily for 20 min in a month. The control group received no intervention except for usual care. Data were assessed using the Nottingham Extended Activitıes of Daily Living (NEADL) scale.

RESULTS

The mean age of the subjects was 50.32 ± 7.23 years and 78.4% (n = 51) were male. The odds of higher degree of independence regarding NEADLS was about 25% greater in the intervention group as compared to the control one (OR: 1.24; 95% CI: 1.07, 1.44; P = 0.001).

CONCLUSION

Findings suggest that using BRT as a non-pharmacological intervention may effectively enhance the ADLs of HD patients.

Darbepoetin Alfa in Patients with Advanced CKD without Diabetes: Randomized, Controlled Trial

BACKGROUND AND OBJECTIVES

Large, randomized, controlled trials targeting higher hemoglobin level with erythropoiesis-stimulating agents for Western patients with CKD showed harm. However, the effect of anemia correction using erythropoiesis-stimulating agents may differ between CKD subpopulations. The Prevention of ESKD by Darbepoetin Alfa in CKD Patients with Non-diabetic Kidney Disease study, a multicenter, randomized, open-label, parallel-group study, aimed to examine the effect of targeting hemoglobin levels of 11-13 g/dl using darbepoetin alfa with reference to a low-hemoglobin target of 9-11 g/dl on kidney outcome in patients with advanced CKD without diabetes in Japan.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We enrolled 491 patients with CKD without diabetes, and an eGFR of 8-20 ml/min per 1.73 m². Of these 491 patients, 239 and 240 were ultimately assigned to the high- and low-hemoglobin groups, respectively (12 patients were excluded). The primary outcome was a kidney composite end point (starting maintenance dialysis, kidney transplantation, eGFR≤6 ml/min per 1.73 m², and 50% reduction in eGFR).

RESULTS

Mean hemoglobin levels were 11.2±1.1 and 10.0±0.9 g/dl in the high- and low-hemoglobin groups, respectively, during the mean study period of 73.5±29.7 weeks. The kidney composite end point occurred in 105 (44%) and 116 (48%) patients in the high- and low-hemoglobin groups, respectively (log-rank test; P=0.32). The adjusted Cox proportional hazards model showed that the hazard ratio for the high- versus low-hemoglobin group was 0.78 (95% confidence interval, 0.60 to 1.03; P=0.08). Cardiovascular events occurred in 19 (8%) and 16 (7%) patients in each group, respectively, with no significant between-group difference (log-rank test; P=0.66).

CONCLUSIONS

Targeting a higher hemoglobin level (11-13 g/dl) with darbepoetin alfa did not improve kidney outcome compared with targeting a lower hemoglobin level (9-11 g/dl) in patients with advanced CKD without diabetes.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Prevention of ESKD by Darbepoetin Alfa in CKD Patients with Non-diabetic Kidney Disease (PREDICT), NCT01581073.

Time-averaged proteinuria during follow-up and renal prognosis in patients with biopsy-proven benign nephrosclerosis

BACKGROUND

Heavy proteinuria at diagnostic renal biopsy has been reported as an independent risk factor for deteriorating renal function in benign nephrosclerosis (BNS). However, studies investigating the relationship between the amount of proteinuria during follow-up and long-term renal prognosis in BNS are limited. This study aimed to assess the relationship between time-averaged proteinuria (TAP) and renal prognosis in BNS.

METHODS

The study participants included 98 patients with biopsy-proven BNS (average age 52 ± 13 years, estimated glomerular filtration rate (eGFR) 53 ± 25 ml/min/1.73 m², urine protein excretion at baseline 1.34 ± 1.30 g/gCr) from the Jikei University Hospital. Multivariate analysis was used to investigate the effects of TAP and other clinicopathological findings on the risk for renal outcome in biopsy-proven BNS (a 30% decline in eGFR from baseline or end-stage renal disease). Proteinuria was measured every 6 months and the mean value was used as an indicator of TAP.

RESULTS

The average observation period was 56 ± 43 months. In the unadjusted model, higher levels of TAP and urinary protein at baseline, glomerulosclerosis, and tubulointerstitial damage were associated with renal prognosis. The adjusted model demonstrated a significant association between TAP and renal outcomes (hazard ratio 5.45, 95% confidence interval 3.02-10.7), which was independent of higher baseline proteinuria, glomerulosclerosis, and tubulointerstitial damage.

CONCLUSIONS

TAP is an independent risk factor for renal prognosis in patients with BNS, indicating the significance of urinary protein excretion during follow-up for the progression of BNS. Clinicians should understand the importance of follow-up evaluation for proteinuria in patients with BNS.

High-normal albuminuria is strongly associated with incident chronic kidney disease in a nondiabetic population with normal range of albuminuria and normal kidney function

BACKGROUND

Albuminuria and estimated glomerular filtration rate (eGFR) are clinically measured to evaluate the severity of chronic kidney disease (CKD). The aim of our study was to clarify the association between clinical parameters, including albuminuria and eGFR, and the risk of incident CKD in a nondiabetic population with normal range of albuminuria and eGFR.

METHODS

A 10-year follow-up, retrospective cohort study involving 317 Japanese men (mean age, 42 years) with eGFR ≥ 90 mL/min/1.73 m² and urine albumin-to-creatinine ratio (UACR) < 30 mg/gCr was performed. Participants were free of diabetes mellitus. Multivariate logistic regression approaches were used to assess independent predictors of the incidence of CKD.

RESULTS

Twenty-nine (9%) participants developed CKD (eGFR < 60 mL/min/1.73 m² and/or UACR ≥ 30 mg/gCr) through 10 years of follow-up. At the baseline examination, age, blood pressure, UACR, and eGFR were higher in participants who developed CKD than in those without CKD. After adjustment for confounders, high-normal albuminuria (P < 0.001) and hypertension (P = 0.045) were associated with an increased incidence of CKD. From receiver-operating characteristic curves, UACR ≥ 7.0 mg/gCr was defined as high-normal albuminuria. Logistic regression analysis also showed that, in addition to presence of hypertension, UACR ≥ 7.0 mg/gCr was identified as an independent risk of incident CKD within 10 years after adjustment for age, body mass index, smoking status, and dyslipidemia [UACR: odds ratio (OR) 17.36 (95% CI 6.16-48.93, P < 0.001)].

CONCLUSION

High-normal albuminuria and hypertension are associated with incident CKD in a nondiabetic population with normal-range UACR and eGFR.

Urine 5MedC, a Marker of DNA Methylation, in the Progression of Chronic Kidney Disease

Background

Alterations in DNA methylation may be involved in disease progression in patients with chronic kidney disease (CKD). Recent studies have suggested that 5-methyl-2′-deoxycytidine (5MedC) may be a marker of hypermethylation of DNA. Currently, there is no information available regarding the urine levels of 5MedC and its association with the progression of CKD.

Method

We examined the urine levels of 5MedC in spot urine samples from 308 patients with CKD (median age: 56 years, male: 53.2%, and glomerulonephritis: 51.0%) using a competitive enzyme-linked immunosorbent assay and investigated the relationships among urine 5MedC, urine albumin, urine α1-microglobulin (α1MG), and the laboratory parameters associated with CKD. The patients were followed for three years to evaluate renal endpoints in a prospective manner.

Results

The urine 5MedC level was significantly increased in the later stages of CKD compared to the early to middle stages of CKD. In multiple logistic regression models, urine 5MedC was significantly associated with the prediction of later CKD stages. Urine 5MedC (median value, 65.9 μmol/gCr) was significantly able to predict a 30% decline in the estimated GFR or a development of end-stage renal disease when combined with macroalbuminuria or an increased level of urine α1MG (median value, 5.7 mg/gCr).

Conclusion

The present data demonstrate that the urine 5MedC level is associated with a reduced renal function and can serve as a novel and potent biomarker for predicting the renal outcome in CKD patients. Further studies will be necessary to elucidate the role of urine DNA methylation in the progression of CKD.

Kidney cytosine methylation changes improve renal function decline estimation in patients with diabetic kidney disease

Epigenetic changes might provide the biological explanation for the long-lasting impact of metabolic alterations of diabetic kidney disease development. Here we examined cytosine methylation of human kidney tubules using Illumina Infinium 450 K arrays from 91 subjects with and without diabetes and varying degrees of kidney disease using a cross-sectional design. We identify cytosine methylation changes associated with kidney structural damage and build a model for kidney function decline. We find that the methylation levels of 65 probes are associated with the degree of kidney fibrosis at genome wide significance. In total 471 probes improve the model for kidney function decline. Methylation probes associated with kidney damage and functional decline enrich on kidney regulatory regions and associate with gene expression changes, including epidermal growth factor (EGF). Altogether, our work shows that kidney methylation differences can be detected in patients with diabetic kidney disease and improve kidney function decline models indicating that they are potentially functionally important.

Patients with diabetes commonly develop diabetic kidney disease (DKD). Here Gluck et al. identify a set of probes differentially methylated in renal samples from patients with DKD, and find that inclusion of these methylation probes improves current prediction models of renal function decline.

Higher medical costs for CKD patients with a rapid decline in eGFR: A cohort study from the Japanese general population

To investigate how changes in eGFR can affect medical costs, a regional cohort of national health insurance beneficiaries in Japan was developed from a nationwide database system (Kokuho database, KDB), and non-individualized data were obtained. From 105,661 people, subjects on chronic dialysis and subjects without consecutive medical checkups were excluded. Finally, medical costs in the follow-up year categorized by annual changes in eGFR between baseline and the next year were longitudinally examined in 70,627 people ranging in age from 40 to 74 years. Global mean costs for subjects with a rapid decrease in eGFR (≤-30%/year) were the highest among all ΔeGFR categories. In men, the cost was 1.42 times that for a stable eGFR. A total of 6,268 (19.4%) men and 5,381 (14.0%) women with eGFR <60 ml/min/1.73 m² were identified in the baseline year. The mean cost was higher with a low eGFR than without a low eGFR, and there were also higher proportions newly initiating dialysis in 2014 (low eGFR with rapid decrease in eGFR vs. with stable eGFR: 9.61% vs. 0.02% in women, P<0.001). Moreover, the costs for low eGFR subjects with a rapid decrease in eGFR were more than twice those of non-low eGFR subjects with a rapid decrease in eGFR and also compared to low eGFR subjects with a stable eGFR. Moreover, initiating chronic dialysis was considered one of the major causes of high medical costs in women with rapid eGFR decline. To the best of our knowledge, this is the first study of renal disease using a cohort developed from the KDB system recently established in Japan.

Identifying progressive CKD from healthy population using Bayesian network and artificial intelligence: A worksite-based cohort study

Identifying progressive early chronic kidney disease (CKD) patients at a health checkup is a good opportunity to improve their prognosis. However, it is difficult to identify them using common health tests. This worksite-based cohort study for 7 years in Japan (n = 7465) was conducted to evaluate the progression of CKD. The outcome was aggravation of the KDIGO prognostic category of CKD 7 years later. The subjects were male, 59.1%; age, 50.1 ± 6.3 years; and eGFR, 79 ± 14.4 mL/min/1.73 m2. The number of subjects showing CKD progression started to increase from 3 years later. Vector analysis showed that CKD stage G1 A1 was more progressive than CKD stage G2 A1. Bayesian networks showed that the time-series changes in the prognostic category of CKD were related to the outcome. Support vector machines including time-series data of the prognostic category of CKD from 3 years later detected the high possibility of the outcome not only in subjects at very high risks but also in those at low risks at baseline. In conclusion, after the evaluation of kidney function at a health checkup, it is necessary to follow up not only patients at high risks but also patients at low risks at baseline for 3 years and longer.

Estimated glomerular filtration rate decline and risk of end-stage renal disease in type 2 diabetes

Background

According to studies by the National Kidney Foundation and Food and Drug Administration, 30% and 40% declines in estimated glomerular filtration rate (eGFR) could be used as surrogate endpoints of end-stage renal disease (ESRD). However, the benefits of using these endpoints in diabetic patients remain unclear.

Methods

This cohort study comprised Japanese patients with type 2 diabetes; those with repeated serum creatinine measurements during a baseline period of 2 years (n = 1868) or 3 years (n = 2001) were enrolled. Subsequent risks of ESRD following eGFR declines were assessed.

Results

In the 2-year baseline analysis, the cumulative prevalence of −20%, −30%, −40%, and −53% changes in eGFR were 23.9%, 11.1%, 6.8%, and 3.7%, respectively. There were 133 cases (7.1%) of subsequent ESRD during a median follow-up period of 6.5 years. In the 3-year baseline analysis, the corresponding proportions were 28.1%, 14.0%, 7.7%, and 3.9%, respectively, with 110 participants (5.5%) reaching ESRD during a median follow-up period of 5.5 years. The adjusted hazard ratios of subsequent ESRD following −53%, −40%, −30%, and −20% changes in eGFR during the 2-year baseline period were 22.9 (11.1–47.3), 12.8 (6.9–23.7), 8.2 (4.3–15.5), and 3.9 (2.2–7.0), respectively when compared with the no changes in eGFR. In the 3-year baseline analysis, the corresponding risks were 29.7 (10.8–81.9), 18.4 (7.6–44.7), 12.8 (5.2–32.2), and 5.4 (2.3–12.8), respectively. In the subgroup analysis, similar trends were observed in patients with macroalbuminuria at baseline.

Conclusions

Declines in eGFR were strongly associated with subsequent risk of ESRD in Japanese type 2 diabetic patients. In addition to 30% and 40% declines, a 20% decline in eGFR over 2 years could be considered as a candidate surrogate endpoint of ESRD in diabetic kidney disease.

Urinary type IV collagen excretion is involved in the decline in estimated glomerular filtration rate in the Japanese general population without diabetes: A 5-year observational study

Urinary type IV collagen (U-Col4) and albumin excretion is evaluated to monitor the development of diabetic kidney disease. However, U-Col4 excretion in the general population without diabetes has not yet been fully elucidated. In this study, 1067 participants without diabetes and with urinary albumin-creatinine ratio <300 mg/gCr (normo- or microalbuminuria) who underwent an annual health examination in 2004 were enrolled and observed for 5 years. They were divided according to the amount of U-Col4 or urinary albumin excreted. The decline in estimated glomerular filtration rate (eGFR) was calculated. In participants with eGFR ≥80 mL/min, abnormal U-Col4 excretion was indicated as a significant independent risk factor for 10% eGFR change per year, which is one of the prognostic factors for the development of end-stage kidney disease. Moreover, in contrast to urinary albumin excretion, U-Col4 excretion was not related to age or kidney function, suggesting that some individuals with abnormal U-Col4 excretion can have an independent hidden risk for the development of kidney dysfunction. In conclusion, it is important to measure U-Col4 excretion in the general population without diabetes to determine changes in renal features in every individual and help detect future complications such as diabetic kidney disease. If U-Col4 excretion is abnormal, kidney manifestation should be carefully followed up, even if the kidney function and urinalysis findings are normal.