Performance of GFR equations in Japanese subjects

Association of Lower Extremity Muscle Strength and Function with Renal Resistive Index in Individuals with and without Chronic Kidney Disease

Age-related loss of lower extremity muscle strength is pronounced in individuals with chronic kidney disease (CKD). In contrast, an increase in intrarenal flow pulsatility results in initial age-related changes in renal hemodynamics, leading to the development of CKD. To date, it remains unclear whether lower extremity muscle strength determines elevated renal flow pulsatility. This study aimed to determine the association of lower extremity muscle strength and function with intrarenal hemodynamics in individuals with and without CKD. One hundred seventy-six individuals without CKD (aged 63 ± 9 years) and 101 individuals with CKD (aged 66 ± 8 years) were included in this study. Using Doppler ultrasound, the renal resistive index (RI) was measured as a parameter of renal hemodynamics. Knee extensor muscle strength (KES), gait speed (GS), and the 30 s chair stand test (30s-CST) were used to measure lower extremity muscle strength and function. Multivariate analyses showed that GS and 30s-CST scores were independent determinants of renal RI, whereas the KES score was not associated with renal RI in individuals with and without CKD. In the two-way analysis of covariance, renal RI was the highest in individuals with CKD who had lower KES, GS, and 30s-CST scores. Reduced lower extremity muscle strength and function are independent determinants of elevated renal flow pulsatility in individuals with and without CKD.

Change in Liver Fibrosis Associates with Progress of Diabetic Nephropathy in Patients with Nonalcoholic Fatty Liver Disease

Diabetic nephropathy (DN) is a major complication of diabetes. Nonalcoholic fatty liver disease (NAFLD) is common in diabetes, and liver fibrosis is a prognostic risk factor for NAFLD. The interaction between DN and liver fibrosis in NAFLD remains unclear. In 189 patients with DN and NAFLD who received an education course about diabetic nephropathy, liver fibrosis was evaluated using the fibrosis-4 (FIB-4) index. The association between the outcome of DN and changes in liver fibrosis was examined. The FIB-4 index was maintained at the baseline level in patients with improved DN, while it was increased in other patients. The ΔFIB-4 index was positively correlated with changes in albuminuria and proteinuria (ρ = 0.22, p = 0.004). In a multivariate analysis, changes in albuminuria and proteinuria were associated with the ΔFIB-4 index (p = 0.002). Patients with a progressive FIB-4 index category from baseline to 5 years showed a lower event-free survival rate after 5 years than patients with an improved FIB-4 index category (p = 0.037). The outcome of DN is associated with changes in liver fibrosis in patients with diabetes, NAFLD and DN. Developing a preventive and therapeutic approach for these conditions is required.

Association between trunk flexibility and renal flow pulsatility in middle-aged and older adults

BACKGROUND

Recent clinical studies have indicated that poor trunk flexibility is associated with arterial stiffness in the aged. Arterial stiffness leads to elevated renal flow pulsatility, which accelerates age-related renal dysfunction and damages. However, data indicating the potential link between flexibility fitness and renal flow pulsatility are lacking. This study examined the cross-sectional association between trunk flexibility and renal flow pulsatility in middle-aged and older adults.

METHODS

A total of 175 middle-aged and older adults (aged 63 ± 9 years) were included in this study. Sit-and-reach tests (SRT) were performed to assess their trunk flexibility. Using a Doppler ultrasound, renal pulsatility index (PI) and resistive index (RI) were measured as parameters of renal flow pulsatility.

RESULTS

The study found that, in middle-aged and older adults, the SRT score was an independent determinant of renal PI (β = -0.134, P = 0.027) and RI (β = -0.135, P = 0.027). In the one-way analysis of covariance (ANCOVA), the renal PI and RI in the older group with a lower SRT score were found to be significantly higher than those in the middle-aged group.

CONCLUSIONS

Trunk flexibility is an independent determinant of renal flow pulsatility in middle-aged and older adults.

Association between the intake of plant and animal proteins and the serum fibroblast growth factor-23 level in patients with chronic kidney disease analyzed by the isocaloric substitution model

Fibroblast growth factor-23 (FGF23) is a phosphaturic hormone secreted by the bone in response to dietary phosphate intake. Since the phosphate content in the diet correlates with the protein content, both plant- and animal-based protein intake can increase the serum FGF23 level. However, a higher percentage of energy from plant protein than from animal protein is associated with a lower serum FGF23 level in patients with chronic kidney disease (CKD) in the United States. Since dietary habits differ between Asian and Western populations, we performed a cross-sectional study to determine the association between the percentages of energy from plant and animal proteins and the serum FGF23 level in Japanese CKD patients. In 107 non-dialysis CKD patients (age: 66 ± 9 years; estimated glomerular filtration rate: 56 ± 21 mL/min/1.73 m²), the percentages of energy from plant and animal proteins were assessed using a food frequency questionnaire based on food groups. Venous blood samples were used to measure the serum FGF23, phosphate, 1,25-dihydroxyvitamin D, and intact parathyroid hormone levels. The percentages of energy from plant and animal proteins showed a negative and positive association, respectively, with the serum FGF23 level. Furthermore, isocaloric substitution modeling showed that replacing animal protein with plant protein was associated with a low serum FGF23 level. Our findings suggest that encouraging diets with high plant protein level may prevent an increase in the serum FGF23 level in Japanese CKD patients.

Glomerular filtration in the aging population

In the last decades, improvements in the average life expectancy in the world population have been associated with a significant increase in the proportion of elderly people, in parallel with a higher prevalence of non-communicable diseases, such as hypertension and diabetes. As the kidney is a common target organ of a variety of diseases, an adequate evaluation of renal function in the approach of this population is of special relevance. It is also known that the kidneys undergo aging-related changes expressed by a decline in the glomerular filtration rate (GFR), reflecting the loss of kidney function, either by a natural senescence process associated with healthy aging or by the length of exposure to diseases with potential kidney damage. Accurate assessment of renal function in the older population is of particular importance to evaluate the degree of kidney function loss, enabling tailored therapeutic interventions. The present review addresses a relevant topic, which is the effects of aging on renal function. In order to do that, we analyze and discuss age-related structural and functional changes. The text also examines the different options for evaluating GFR, from the use of direct methods to the implementation of several estimating equations. Finally, this manuscript supports clinicians in the interpretation of GFR changes associated with age and the management of the older patients with decreased kidney function.

HSPA8 Single-Nucleotide Polymorphism Is Associated with Serum HSC70 Concentration and Carotid Artery Atherosclerosis in Nonalcoholic Fatty Liver Disease

There is an association between nonalcoholic fatty liver disease (NAFLD) and atherosclerosis, but the genetic risk of atherosclerosis in NAFLD remains unclear. Here, a single-nucleotide polymorphism (SNP) of the heat shock 70 kDa protein 8 (HSPA8) gene was analyzed in 123 NAFLD patients who had been diagnosed using a liver biopsy, and the NAFLD phenotype including the maximum intima–media thickness (Max-IMT) of the carotid artery was investigated. Patients with the minor allele (A/G or G/G) of rs2236659 showed a lower serum heat shock cognate 71 kDa protein concentration than those with the major A/A allele. Compared with the patients with the major allele, those with the minor allele showed a higher prevalence of hypertension and higher Max-IMT in men. No significant associations between the HSPA8 genotype and hepatic pathological findings were identified. In decision-tree analysis, age, sex, liver fibrosis, and HSPA8 genotype were individually associated with severe carotid artery atherosclerosis (Max-IMT ≥ 1.5 mm). Noncirrhotic men aged ≥ 65 years were most significantly affected by the minor allele of HSPA8. To predict the risk of atherosclerosis and cardiovascular disease, HSPA8 SNP genotyping might be useful, particularly for older male NAFLD patients.

Daily behavioral and sleep patterns are associated with aging-induced male-specific disorders in individuals with reduced renal function

BACKGROUND

The development of aging-induced male-specific disorders is accelerated by impaired renal function. Although aging-induced male-specific disorders are clinically serious complications in individuals with reduced renal function, their practical management strategies remain obscure. The purpose of this cross-sectional study was to investigate the association between daily behavioral and sleep patterns and aging-induced male-specific disorders in individuals with reduced renal function.

METHODS

Eighty men with glomerular filtration rate stage 2-4 (age, 67 ± 9 years), sedentary behavior and physical activity were assessed using a triaxial accelerometer. The mean sleep time was calculated from the sleep time during the accelerometer measurement. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Aging-induced male-specific disorders were assessed using the Aging Males' Symptoms Questionnaire (AMS).

RESULTS

A lower moderate to vigorous-intensity physical activity (MVPA) time and a higher PSQI score were independently associated with a higher AMS score. Moreover, when the participants were divided into four groups according to the median MVPA values and the PSQI score (more or less than 6 points), the AMS score was the highest in those with a lower MVPA time and a higher PSQI score. In the mediation analysis, the PSQI score did not mediate a correlation between the MVPA time and AMS score. MVPA time also did not mediate a correlation between the PSQI and AMS scores.

CONCLUSIONS

Collectively, these findings suggest that increasing MVPA time and improving sleep quality may contribute to attenuating aging-induced male-specific disorders in individuals with reduced renal function.

Association of circulating calciprotein particle levels with skeletal muscle mass and strength in middle-aged and older adults

Calciprotein particles (CPPs) are tiny mineral-protein aggregates consisting of calcium-phosphate and fetuin-A. Recent studies have suggested that CPPs may contribute to the pathogenesis of chronic inflammation and arteriosclerosis. Reduced skeletal muscle mass and strength reportedly contribute independently to increased serum phosphate levels. This finding suggests that reduced skeletal muscle mass and strength can endogenously induce an increase in circulating CPP levels. Therefore, we investigated the potential association between circulating CPP levels and skeletal muscle mass and strength in middle-aged and older adults. One hundred eighty-two middle-aged and older adults (age, 46-83 years) were included in this cross-sectional study (UMIN000034741). Circulating CPP levels were measured using the gel filtration method. Appendicular skeletal muscle mass was assessed using multifrequency bioelectrical impedance analysis with a tetrapolar eight-point tactile electrode system. The skeletal muscle mass index was calculated from appendicular skeletal muscle mass and height. Handgrip and knee extension strengths were used as measures of skeletal muscle strength. The skeletal muscle mass index was negatively correlated with circulating CPP levels (r = -0.31; P < 0.05). This association remained significant after adjustment for potential covariates (β = -0.34; P < 0.05). In contrast, skeletal muscle strength, represented by handgrip strength and knee extension strength, was not significantly associated with circulating CPP levels. In middle-aged and older adults, a lower skeletal muscle mass index was independently associated with higher circulating CPP levels. The present results suggest that maintaining skeletal muscle mass may prevent an increase in circulating CPP levels.

Circulating fibroblast growth factor 21 links hemodynamics with kidney function in middle-aged and older adults: A mediation analysis

Altered hemodynamics are commonly observed in individuals with declining renal function; however, the pathophysiological mechanisms linking renal dysfunction and hemodynamics have not been fully elucidated. Fibroblast growth factor 21 (FGF21), which upregulates sympathetic nerve activity, can alter systemic hemodynamics, and its level can increase as renal function declines. This study aimed to determine the associations among circulating FGF21 levels, hemodynamics, and renal function in middle-aged and older adults. In a total of 272 middle-aged and older adults (age range: 46-83 years), estimated glomerular filtration rate (eGFR), hemodynamics (brachial and aortic blood pressure and aortic pulse wave velocity [PWV]), and serum FGF21 levels were measured. For mediation analysis, hemodynamic parameters were entered as outcomes. eGFR or log-transformed urinary albumin and creatinine ratio (UACR) and log-transformed serum FGF21 levels were set as the predictors and mediator, respectively. According to multivariable regression models after adjusting for potential covariates, serum FGF21 levels were significantly associated with brachial systolic blood pressure (β = 0.140), pulse pressure (β = 0.136), and aortic PWV (β = 0.144). Mediation analyses showed that serum FGF21 levels significantly mediated the relationship of eGFR with brachial systolic blood pressure (indirect effect [95% confidence interval]: -0.032 [-0.071, -0.002]), pulse pressure (-0.019 [-0.041, -0.001]), and aortic PWV (-0.457 [-1.053, -0.021]) and the relationship of UACR with aortic PWV (7.600 [0.011, 21.148]). These findings suggest that elevated circulating FGF21 levels partially mediate the association of elevated blood pressure and/or aortic stiffness with renal dysfunction in middle-aged and older adults.

Replacing sedentary time for physical activity on bone density in patients with chronic kidney disease

INTRODUCTION

This study aimed to examine the cross-sectional associations of sedentary time and physical activity time with bone density in patients with chronic kidney disease (CKD). The isotemporal substitution (IS) modeling was used to estimate the beneficial effects of behavioral changes (e.g., replacing sedentary time with physical activity time) on bone density in these patients.

MATERIALS AND METHODS

A total of 92 patients with CKD (age: 65 ± 9 years; estimated glomerular filtration rate: 57 ± 22 mL/min/1.73 m²) were included in this cross-sectional study. The times spent in sedentary behavior (SB), light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) were assessed using a triaxial accelerometer. Through quantitative ultrasound measurements, the stiffness index, as a measure of bone density, was calculated using the speed of sound and broadband ultrasound attenuation.

RESULTS

In multivariate analyses, the stiffness index was beneficially associated with the MVPA time (β = 0.748), but was not significantly associated with the SB and LPA times. The IS models showed that replacing 10 min/day of SB with the equivalent LPA time was not significantly associated with the stiffness index; however, replacing 10 min/day of SB with the equivalent MVPA time was beneficially associated with the stiffness index (β = 0.804).

CONCLUSION

These results suggest that a small increase in MVPA time (e.g., 10 min/day) may attenuate the decline in bone density in patients with CKD. Our findings may provide insight for the development of novel strategies for improving bone health in patients with CKD.

The Modified Chronic Kidney Disease Epidemiology Collaboration Equation for the Estimated Glomerular Filtration Rate Is Better Associated with Comorbidities than Other Equations in Living Kidney Donors in Japan

Objective We studied three types of estimated glomerular filtration rate (eGFR) equations and evaluated which type was strongly associated with comorbidities in living kidney transplantation (LKT) donors. Methods We compared the Japanese modified eGFR, Modification of Diet in Renal Disease, and Chronic Kidney Disease Epidemiology Collaboration equations (Jm-eGFR, Jm-MDRD, and Jm-CKD-EPI, respectively) for Japanese LKT donors with respect to their relationships with obesity, hypertension, diabetes, cardiovascular disease, and stroke. Results Of the 8,176 enrolled Japanese LKT donors, the eGFR calculated using Jm-CKD-EPI (eGFR/Jm-CKD-EPI) detected significant differences in 4 of 5 comorbidities between the comorbidity-positive and comorbidity-negative groups, whereas the eGFR calculated using Jm-MDRD (eGFR/Jm-MDRD) and Jm-eGFR (eGFR/Jm-eGFR) detected only 3 and 1 comorbidities, respectively. The area under the receiver operating characteristic curve of Jm-CKD-EPI was larger than those of Jm-eGFR and Jm-MDRD for all five comorbidities. Conclusion We found that the eGFR/Jm-CKD-EPI correlated better with comorbidities than the eGFR/Jm-eGFR and eGFR/Jm-MDRD in Japanese LKT donors. We recommend using the eGFR/Jm-CKD-EPI for the initial assessment of the renal function in LKT donor candidates when evaluating the presence of associated comorbidities.

Physical Activity, Sedentary Behavior, and Skeletal Muscle Strength in Patients With Chronic Kidney Disease: An Isotemporal Substitution Approach

OBJECTIVE

Insufficient physical activity and excessive sedentary behavior can contribute to decreased skeletal muscle strength, which is strongly associated with increased mortality in patients with chronic kidney disease (CKD). However, the potential impact of replacing sedentary behavior with physical activity on skeletal muscle strength remains unclear in these individuals. The purpose of this study was to examine the associations of physical activity, sedentary behavior, and skeletal muscle strength in patients with CKD using an isotemporal substitution model to estimate the associations on replacing time from one behavior to another while keeping the total time and other behaviors fixed.

METHODS

A total of 108 patients with CKD (mean age = 65 [SD = 9] y; mean estimated glomerular filtration rate = 57 [SD = 22] mL/min/1.73 m2) participated in this cross-sectional analysis study. The time spent in sedentary behavior, light-intensity physical activity, and moderate- to vigorous-intensity physical activity (MVPA) was assessed using a triaxial accelerometer. Handgrip strength, isometric knee extension strength, and 30-second chair stand test were used to measure skeletal muscle strength.

RESULTS

In multivariate analyses (single-factor and partition models), the time spent in MVPA was beneficially associated with both isometric knee extension strength and 30-second chair stand test. Furthermore, the isotemporal substitution model found that replacing 10 min/d of sedentary behavior or light-intensity physical activity with equivalent MVPA time was beneficially associated with both isometric knee extension strength and 30-second chair stand test.

CONCLUSION

These cross-sectional findings indicate that MVPA time is beneficially associated with lower extremity muscle strength and that a slight increase in the MVPA time may contribute to maintaining skeletal muscle strength in patients with CKD.

IMPACT

Increasing the time spent in MVPA (10 min/d) may be a feasible strategy in patients with CKD who have a high prevalence of impaired physical function.

TYK2 Promoter Variant Is Associated with Impaired Insulin Secretion and Lower Insulin Resistance in Japanese Type 2 Diabetes Patients

Accumulating evidence has suggested that viral infection causes type 1 diabetes due to direct β-cell damage and the triggering of autoimmune reactivity to β cells. Here, we elucidated that the tyrosine kinase 2 (Tyk2) gene, encoding an interferon receptor signaling molecule, is responsible for virus-induced diabetes in mice, and its promoter variant confers a risk of type 1 diabetes in humans. This study investigated the relationship between a TYK2 promoter variant (TYK2PV) and insulin secretion in type 2 diabetes patients. TYK2PV status was determined using direct DNA sequencing and its associations with fasting insulin, C-peptide, and homeostatic model assessment of insulin resistance (HOMA-IR) were evaluated in type 2 diabetes patients without sulfonylurea or insulin medication. Of the 172 patients assessed, 18 (10.5%) showed TYK2PV-positivity. Their body mass index (BMI) was significantly lower than in those without the variant (23.4 vs. 25.4 kg/m², p = 0.025). Fasting insulin (3.9 vs. 6.2 μIU/mL, p = 0.007), C-peptide (1.37 vs. 1.76 ng/mL, p = 0.008), and HOMA-IR (1.39 vs. 2.05, p = 0.006) were lower in those with than in those without the variant. Multivariable analysis identified that TYK2PV was associated with fasting insulin ≤ 5 μIU/mL (odds ratio (OR) 3.63, p = 0.025) and C-peptide ≤ 1.0 ng/mL (OR 3.61, p = 0.028), and also lower insulin resistance (HOMA-IR ≤ 2.5; OR 8.60, p = 0.042). TYK2PV is associated with impaired insulin secretion and low insulin resistance in type 2 diabetes. Type 2 diabetes patients with TYK2PV should be carefully followed in order to receive the appropriate treatment including insulin injections.

Fractional excretion of tumor necrosis factor receptor 1 and 2 in patients with type 2 diabetes and normal renal function

AIMS/INTRODUCTION

Increased concentrations of serum tumor necrosis factor (TNF) receptors (TNFRs; TNFR1 and TNFR2) are positively associated with the urinary albumin-to-creatinine ratio (ACR), and negatively associated with the estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes. However, the mechanism underlying this increase and the relationship between TNFRs in serum, and urine and kidney measures (ACR and eGFR) are unclear.

MATERIALS AND METHODS

This was a cross-sectional study that included 499 patients with type 2 diabetes and eGFR ≥60 mL/min/1.73 m2 . The concentrations of TNFRs in serum and urine, and their respective fractional excretion, were measured.

RESULTS

Serum and urinary TNFR levels were positively associated with the ACR, and negatively associated with the eGFR. The fractional excretion of TNFRs did not differ between patients with an eGFR ≥90 and those with an eGFR 60-89 mL/min/1.73 m2 , and also did not correlate with eGFR. After adjustment for relevant covariates, the serum TNFRs were associated with a lower eGFR (60-89 mL/min/1.73 m2 ) and an increased ACR (≥30 mg/gCr), but urinary TNFRs were associated with an increased ACR (≥30 mg/gCr) alone, in the multivariate logistic model.

CONCLUSIONS

The pattern of fractional excretion TNFRs showed that an increase in serum TNFRs might result from their increased systemic production, including in the kidney, rather than being a simple reflection of GFR decline. Kidney measures appear to be strongly associated with serum TNFRs rather than urinary TNFRs in patients with type 2 diabetes and normal renal function.

FIB-4 index-based surveillance for advanced liver fibrosis in diabetes patients

Liver fibrosis is associated with lifestyle-related diseases, including diabetes. The identification of diabetic patients with severe liver fibrosis is important, but a simple and reliable diagnostic procedure remains to be determined. We conducted an observational study to evaluate the performance of a FIB-4 index-based screening strategy for the diagnosis of advanced liver fibrosis in patients with diabetes or prediabetes. Two hundred and forty-two patients underwent abdominal imaging in our Study. According to the abdominal imaging findings, fatty liver, liver cirrhosis, and hepatocellular carcinoma were defined, and their association with FIB-4 index evaluated. The prevalences of liver cirrhosis and hepatocellular carcinoma in patients with a high (≥ 2.67; liver cirrhosis: 42.9%, hepatocellular carcinoma: 14.3%) FIB-4 index were significantly higher than in those with an intermediate (1.3 ≤ FIB-4 < 2.67; liver cirrhosis: 1.6%, hepatocellular carcinoma: 0.8%) or low FIB-4 index (< 1.3; liver cirrhosis: 1.2%, hepatocellular carcinoma: 0%). The diagnostic accuracy, specificity, and sensitivity of the FIB-4 index for the diagnosis of liver cirrhosis or hepatocellular carcinoma were 84.3%, 85.5%, and 89.3%, respectively, with an optimized cut-off value of 2.96 (sensitivity = 0.86, specificity = 0.98). Using an optimized cut-off value, FIB-4 index might be useful to identify liver cirrhosis or hepatocellular carcinoma in diabetes patients with high diagnostic accuracy.

Autologous Blood Donation Before Hepatectomy in Patients With Chronic Kidney Disease

Autologous blood is sometimes collected before hepatectomy. The usefulness of autologous blood donation (ABD) has been reported in several studies. However, the relationship between ABD and CKD has never been studied. The aim of this study was to clarify the relationship between preoperative autologous blood donation (ABD) and chronic kidney disease (CKD) in anemia. Between January 2006 and December 2012, 70 patients made 2 ABDs ≥ 600 mL before hepatectomy. CKD stages were based on estimated glomerular filtration rates. Univariate analyses were performed using the Mann–Whitney U test for continuous variables and the chi-square test for nominal variables. Patients at CKD stages &lt; G3b (n = 60) and ≥ G3b (n = 10) were compared. There were no significant differences in hemoglobin level at the initial hospital visit or total volume of ABD between the 2 groups. However, hemoglobin levels just before the first ABD, the second ABD, and resection, and just after resection were significantly lower in the CKD ≥ G3b group than those in the &lt; G3b group (P &lt; 0.05). CKD stage contributes to reductions in hemoglobin levels after ABD. We recommend the use of erythropoietin in CKD ≥ G3b cases that include ABDs.

Adequacy of decision-making based on each kidney function estimation method for Japanese living kidney donor candidates: a retrospective observational study

Background

Living kidney transplantation comprises the majority of kidney transplantations in Japan. Living kidney donors should be assured of their own health. Therefore, Japanese guidelines define the criterion of kidney function for living donors. Glomerular filtration rates (GFR) ≥ 70 mL/min/1.73 m2 are required for marginal donors. The guidelines require that GFRs of donors be measured by the inulin (In) clearance method (CIn) or the radioisotope method, but these methods can be substituted with the creatinine (Cr) clearance method (CCr). Methods for estimating kidney function are susceptible to error, and decision-making regarding donor eligibility could be affected by the estimation method used. We investigated the adequacy of decision-making based on kidney function estimation methods used in Japanese living kidney donor candidates by comparing CCr or estimated GFR (eGFR), calculated by several equations, and CIn as measured GFR (mGFR).

Methods

In total, 210 people, including 36 actual kidney donor candidates, who had both CIn and CCr measured at Shinshu University Hospital from April 2011 to April 2015, were included. Cr and cystatin C (Cys) levels measured at the same time were used to calculate eGFR (eGFRCr and sGFRCys, respectively). We evaluated the concordance rates of cases whose GFR levels were ≥ 70 mL/min/1.73 m2 in this study and assumed that they were living kidney donor candidates. Only kidney donor candidates underwent an additional sensitivity analysis.

Results

Median CIn and CCr were 55.5 mL/min/1.73 m2 and 68.0 mL/min/1.73 m2, respectively. CCr had the highest tendency to overestimate kidney function. Some participants were incorrectly evaluated as adequate using CCr, despite their mGFR being inadequate for living kidney donors according to the guidelines. These results were independent of sex or actual living kidney donor candidates. The average of eGFRCr and eGFRCys was well correlated with CIn.

Conclusions

Kidney function estimated by CCr is not equal to the mGFR. When using CCr as a kidney function estimation method to determine the adequacy of a living kidney donor, it should be noted that CCr overestimates kidney function. In evaluating adequacy for a marginal donor, GFR estimated by CIn should be assessed.

Body mass index change and estimated glomerular filtration rate decline in a middle-aged population: health check-based cohort in Japan

BACKGROUND

Obesity is a growing public health problem worldwide. We evaluated the mediators and association between changes in obesity metrics and renal outcomes in the general population.

METHODS

Using the Japanese nationwide health check-based cohort from April 2011 to March 2019, we selected individuals aged 40-74 years, with a baseline estimated glomerular filtration rate (eGFR) ≥45 mL/min/1.73 m², whose body mass index (BMI) change was assessed. The primary outcome was combined 30% decline in eGFR, eGFR <15 mL/min/1.73 m² and end-stage renal disease.

RESULTS

During 245 147 person-years' follow-up among 50 604 participants (mean eGFR, 83.7 mL/min/1.73 m²; mean BMI, 24.1 kg/m²), 645 demonstrated eGFR decline (incidence rate 2.6/1000 person-years, 95% CI: 2.4 to 2.8). We observed continued initial changes in BMI for over 6 years and a U-shaped association between BMI change and eGFR decline. Compared with 0% change in BMI, adjusted HRs for changes of -10%, -4%, 4% and 10% were 1.53 (95% CI: 1.15 to 2.04), 1.14 (95% CI: 1.01 to 1.30), 1.16 (95% CI: 1.02 to 1.32) and 1.87 (95% CI: 1.25 to 2.80), respectively. The percentage of excess risk of BMI increase (>4%) mediated by three risk factors (blood pressure, haemoglobin A1c and total cholesterol), was 13.3%.

CONCLUSION

In the middle-aged Japanese population, both, increase and decrease in BMI were associated with subsequent eGFR decline. Changes in risk factors mediated a small proportion of the association between BMI increase and eGFR decline. Our findings support the clinical significance of monitoring BMI as a renal risk factor.

No Race-Ethnicity Adjustment in CKD-EPI Equations Is Required for Estimating Glomerular Filtration Rate in the Brazilian Population

BACKGROUND

Glomerular filtration rate (GFR) is usually estimated from equations using serum creatinine (sCr), with adjustment for gender, age, and race (black or nonblack). The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) is the preferred equation for adults, but it was validated for the United States population. We intended to evaluate if the race-ethnicity adjustment proposed for the sCr-based CKD-EPI equations is appropriate for the Brazilian population.

METHODS

CKD outpatients had blood samples collected for determination of sCr and serum cystatin C (sCys) levels. GFR was measured (mGFR) by plasma clearance of 51Cr-EDTA and used as the reference. We compared values of mGFR and estimated GFR (eGFR) by CKD-EPI equations based on sCr (eGFRCr) and on the combination of sCr and sCys (eGFRCr-Cys). For African Brazilian patients, eGFR was calculated either without or with race adjustment. Accuracy was considered acceptable if the difference between the values of eGFR and mGFR was ≤30% (P30).

RESULTS

100 patients were enrolled (58 ± 14 years, 46% male, 39% white and 61% African Brazilian). Mean mGFR was 46.7 ± 29.2 ml/min/1.73 m2. Mean eGFRCr and eGFRCr-Cys without race adjustment were 47.8 ± 30.1 ml/min/1.73 m2 and 46.4 ± 30.3 ml/min/1.73 m2, respectively. The corresponding P30 accuracy values were 79.0% and 83.0%. In the African Brazilian subgroup, values for mean mGFR and eGFRCr either without or with race adjustment were 49.8 ± 32.2 ml/min/1.73 m2, 50.4 ± 32.7 ml/min/1.73 m2, and 58.4 ± 37.9 ml/min/1.73 m2 (P < 0.001 vs. mGFR), respectively. P30 accuracy values for eGFRCr either without or with race adjustment were 75.4% and 67.2%, respectively.

CONCLUSIONS

The use of CKD-EPI equations without race-ethnicity adjustment seems more appropriate for the Brazilian population.

Increased Glomerular Hydrostatic Pressure is Associated with Tubular Creatinine Reabsorption in Healthy Subjects

<b><i>Background:</i></b> Cr is secreted by the proximal tubules and thus Cr clearance (<i>C</i>_cr) can overestimate inulin clearance (<i>C</i>_in). However, in some cases, <i>C</i>_cr can even underestimate <i>C</i>_in. This suggests that Cr could be reabsorbed in the tubuli. We examined the clinical parameters that are associated with tubular Cr reabsorption. <b><i>Methods:</i></b> In 80 kidney donor candidates (53.9 ± 13.2 years, 29 males), <i>C</i>_in and para-aminohippuric acid clearance were measured simultaneously. Intrarenal hemodynamic parameters were calculated by Gomez’s formulae. To quantify the secretory component of <i>C</i>_cr (SF_cr), it was calculated as follows: SF_cr = (<i>C</i>_cr − <i>C</i>_in)/<i>C</i>_cr. <b><i>Results:</i></b> Twenty-five subjects (31.3%) showed SF_cr values &#x3c;0. SF_cr that correlated significantly and negatively with efferent arteriolar resistance (<i>R</i>_e) and glomerular hydrostatic pressure (<i>P</i>_glo) (<i>R</i>_e: <i>r</i> = −0.30, <i>p</i> = 0.008; <i>P</i>_glo: <i>r</i> = −0.28, <i>p</i> = 0.025). In multiple regression analyses, <i>R</i>_e and <i>P</i>_glo were significantly and negatively associated with SF_cr after adjustment for other confounders. <b><i>Conclusions:</i></b> These findings suggest that tubular reabsorption of Cr can occur in some cases. Intrarenal glomerular hemodynamic burden may be related to tubular creatinine reabsorption, which possibly leads to lower <i>C</i>_cr values.

Protein intake is not associated with progression of diabetic kidney disease in patients without macroalbuminuria

BACKGROUND

Diabetic kidney disease is an important problem in individuals with diabetes. The effect of dietary protein intake on the renal function of patients with diabetes is controversial. Here, we sought to clarify the association between dietary protein intake and changes in the urinary albumin excretion (UAE) or estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes.

METHODS

In this retrospective cohort study, we included 144 patients (70 men, mean ± standard deviation of age 64 ± 10 years, and median (interquartile range) of UAE 15.0 (7.0-38.9) mg/gCr) without an eGFR less than 30 mL/min/1.73 m² and/or UAE greater than or equal to 300 mg/gCr. Changes in the UAE or eGFR were defined as (logarithms [UAE+1] or eGFR at follow-up minus logarithms [UAE+1] or eGFR at baseline examination)/follow-up duration (years). Habitual protein intake was estimated by a self-administered diet history questionnaire.

RESULTS

The median follow-up duration was 5 years. Protein intake (g/kg ideal body weight/day) was not associated with the change in the UAE (r = -0.130, p = 0.120) or change in the eGFR (r = -0.074, p = 0.381). Multiple linear regression analyses showed that after adjusting for covariates, the patients' protein intake was not associated with change in their UAE (standardized regression coefficient: 0.044, p = 0.732) or change in their eGFR (standardized regression coefficient: 0.250, p = 0.085).

CONCLUSIONS

Dietary protein intake does not influence changes in the UAE or eGFR among patients with type 2 diabetes without macroalbuminuria.

Metabolomic profiling to improve glomerular filtration rate estimation: a proof-of-concept study

BACKGROUND

Estimation of glomerular filtration rate (GFR) using estimated glomerular filtration rate creatinine (eGFRcr) is central to clinical practice but has limitations. We tested the hypothesis that serum metabolomic profiling can identify novel markers that in combination can provide more accurate GFR estimates.

METHODS

We performed a cross-sectional study of 200 African American Study of Kidney Disease and Hypertension (AASK) and 265 Multi-Ethnic Study of Atherosclerosis (MESA) participants with measured GFR (mGFR). Untargeted gas chromatography/dual mass spectrometry- and liquid chromatography/dual mass spectrometry-based quantification was followed by the development of targeted assays for 15 metabolites. On the log scale, GFR was estimated from single- and multiple-metabolite panels and compared with eGFR using the Chronic Kidney Disease Epidemiology equations with creatinine and/or cystatin C using established metrics, including the proportion of errors >30% of mGFR (1-P30), before and after bias correction.

RESULTS

Of untargeted metabolites in the AASK and MESA, 283 of 780 (36%) and 387 of 1447 (27%), respectively, were significantly correlated (P ≤ 0.001) with mGFR. A targeted metabolite panel eGFR developed in the AASK and validated in the MESA was more accurate (1-P30 3.7 and 1.9%, respectively) than eGFRcr [11.2 and 18.5%, respectively (P < 0.001 for both)] and estimating GFR using cystatin C (eGFRcys) [10.6% (P = 0.02) and 9.1% (P < 0.05), respectively] but was not consistently better than eGFR using both creatinine and cystatin C [3.7% (P > 0.05) and 9.1% (P < 0.05), respectively]. A panel excluding creatinine and demographics still performed well [1-P30 6.4% (P = 0.11) and 3.4% (P < 0.001) in the AASK and MESA] versus eGFRcr.

CONCLUSIONS

Multimetabolite panels can enable accurate GFR estimation. Metabolomic equations, preferably excluding creatinine and demographic characteristics, should be tested for robustness and generalizability as a potential confirmatory test when eGFRcr is unreliable.

Assessment of renal function in living kidney donors before and after nephrectomy: A Japanese prospective, observational cohort study

OBJECTIVE

To investigate the utility of estimated glomerular filtration rate for assessing kidney function in living kidney donors before and after nephrectomy.

METHODS

A total of 101 donors underwent inulin clearance measurements before and 1 year after nephrectomy. The mean of three inulin clearance values was used as the measured glomerular filtration rate. Estimated glomerular filtration rate based on serum creatinine and cystatin C levels was calculated using the Japanese estimated glomerular filtration rate equation, Chronic Kidney Disease Epidemiology Collaboration formula and new full age spectrum equation. Age-adjusted chronic kidney disease was defined as glomerular filtration rate <75 mL/min/1.73m² for donors aged <40 years, <60 mL/min/1.73m² for donors aged 40-65 years and <45 mL/min/1.73m² for donors aged >65 years.

RESULTS

The postoperative measured glomerular filtration rate <60 mL/min/1.73m² and age-adjusted chronic kidney disease rate were 36.0% and 27.0%, respectively. In younger donors (aged <50 years), postoperative measured glomerular filtration rate <60 mL/min/1.73m² and age-adjusted chronic kidney disease rates were 5.3% and 26.3%, respectively. In older donors (aged >70 years), postoperative measured glomerular filtration rate <60 mL/min/1.73m² and age-adjusted chronic kidney disease rates were 75.0% and 33.3%, respectively. Donor age and measured glomerular filtration rate were significant predictors of postoperative measured glomerular filtration rate. The Japanese estimated glomerular filtration rate equation based on creatinine and cystatin C showed the strongest correlation with measured glomerular filtration rate. However, the Japanese estimated glomerular filtration rate equation based on creatinine overestimated the prevalence of measured glomerular filtration rate <60 mL/min/1.73m² , whereas the Japanese estimated glomerular filtration rate based on cystatin C underestimated it.

CONCLUSIONS

Aged donors might have an increased risk of lower glomerular filtration rate after donor nephrectomy; post-surgery, long-term monitoring of renal function is recommended. Measurement of glomerular filtration rate should be carried out for donors, especially pre-surgery. A more precise glomerular filtration rate equation is required in the future.

Urinary liver-type fatty acid-binding protein levels as a potential risk factor for renal dysfunction in male HIV-infected Japanese patients receiving antiretroviral therapy: a pilot study

Renal dysfunction is recognized with increasing frequency among the non-infectious co-morbidities associated with human immunodeficiency virus (HIV) infection. Recently, urinary liver-type fatty acid-binding protein (L-FABP) was suggested to be a predictor of the progression of renal dysfunction in patients without HIV. However, little is known regarding the utility of urinary L-FABP as a predictor of renal dysfunction in patients with HIV. A retrospective, observational, single-centre study was conducted between July 2014 and December 2016. The primary outcome was renal dysfunction defined as decrease in estimated glomerular filtration rate to less than 60 ml/min/1.73 m². To estimate the effect of urinary L-FABP, proteinuria category, and urinary β2 microglobulin (β2MG) on the time to the first event, a log-rank test was performed. Accuracy, determined by area under the curve and calculated from receiver operating characteristic curves, was also assessed. Thirty Japanese outpatients with HIV receiving antiretroviral therapy (ART) were enrolled. The primary outcome occurred in five patients during the follow-up period. Urinary L-FABP level and proteinuria category were significantly associated with renal dysfunction (p = 0.045 and p = 0.037, respectively). In contrast, urinary β2MG level was not significantly associated with renal dysfunction (p = 0.141). Urinary L-FABP was the most accurate predictor of renal dysfunction among the three urinary parameters. In conclusion, urinary L-FABP levels in HIV patients receiving ART were more accurate for predicting renal dysfunction than proteinuria and urinary β2MG. In addition, urinary L-FABP helped to discriminate those patients with a higher risk for renal dysfunction.

Prospective Comparison of Equations Based on Creatinine and Cystatin C for the Glomerular Filtration Rate Estimation in Chinese Renal Transplant Recipients

BACKGROUND

Currently, there is no dedicated equation to estimate glomerular filtration rate (GFR) for transplanted kidneys. This study aimed to compare the performance of serum creatinine (Scr)- and cystatin C (CysC)-based equations in Chinese renal transplant recipients.

METHODS

A total of 252 stable renal transplant recipients were enrolled in this study. The plasma clearance of ^99mTc-DTPA (rGFR) was used as a reference standard. The Scr, CysC, and rGFR of the patients were measured on the same day. The bias, precision, accuracy (percentage of estimates within 10%, 30%, and 50% of rGFR), and agreements of 8 Scr and 5 CysC eGFR equations were assessed. The factors affecting the accuracy were also evaluated.

RESULTS

Among the Scr-based equations, the Japanese Society of Nephrology-Chronic Kidney Disease Initiatives (JSN-CKDI) equation had the best overall performance with a bias of -6.2 mL/min/1.73 m², and 96.1% of its estimates were within 30% of the rGFR. For the CysC-based equations, the Filler equation had the best performance with a bias of -3.9 mL/min/1.73 m², and 93.7% of its estimates were within 30% of the rGFR. Overall, the CysC-based equations showed better performance than the Scr-based equations. In addition, significant differences were observed between bias and gender and between bias and rGFR value in some equations, whereas transplantation time and immunosuppressive regimens were not correlated with the bias.

CONCLUSION

The JSN-CKDI equation provides the best estimation of the GFR equations, and the CysC-based equations performed better than the Scr-based equations in this population.

Circulating Surfactant Protein-D Is Associated With Clinical Outcomes in Peripheral Artery Disease Patients Following Endovascular Therapy

BACKGROUND

Peripheral artery disease (PAD) is a risk factor for the development of cardiovascular disease and death. Surfactant protein-D (SP-D) is a 43-kDa protein secreted from type II pneumocytes in the lungs. Recent studies have demonstrated that circulating SP-D plays a key role in the development of atherosclerosis and is related to clinical outcomes in patients with ischemic heart disease. However, it remains unclear whether circulating SP-D is associated with clinical outcomes in patients with PAD.Methods and Results:We enrolled 364 patients with PAD who underwent endovascular therapy. We measured serum levels of SP-D and Krebs von den Lungen-6 (KL-6). During a median follow-up period of 974 days, there were 69 major adverse cardiovascular and leg events (MACLE), including 48 major adverse cardiovascular events (MACE). Kaplan-Meier analysis demonstrated that patients with high SP-D (≥110 ng/mL) had higher rates of MACE and MACLE than those with low SP-D. Multivariate Cox proportional hazard regression analysis demonstrated that SP-D, but not KL-6, was an independent predictor of MACE and MACLE. The addition of SP-D to known risk factors significantly improved the C index and net reclassification index. The circulating SP-D level was affected by sex, diabetes mellitus, and cilostazol prescription.

CONCLUSIONS

Circulating SP-D was associated with clinical outcomes in patients with PAD, suggesting that it may be a new therapeutic target in these patients.

The Association between Glomerular Filtration Rate Estimated Using Different Equations and Mortality in the Japanese Community-Based Population: The Yamagata (Takahata) Study

Background

To evaluate renal function, the indices of estimated glomerular filtration rate (eGFR) obtained using several equations, including the Japanese versions of the serum creatinine-based MDRD equation (eGFRcreat), Chronic Kidney Disease Epidemiology Collaboration equation (eGFR-EPI), and serum cystatin C-based equation (eGFRcys), are utilized. This study prospectively examined the association between these eGFR values and all-cause mortality during a 12-year observational period in a community-based population.

Methods and Results

The subjects of this study were 1312 participants undergoing a health checkup, aged ≥40 years. In the total population, the mean eGFR values (mL·min⁻¹·1.73 m⁻²) were 81.5 for eGFRcreat, 78.1 for eGFR-EPI, and 76.6 for eGFRcys. There were 141 deaths during the observation period, and the area under the receiver operating characteristic curve for predicting mortality was 0.59 for eGFRcreat, 0.67 for eGFR-EPI, and 0.70 for eGFRcys (all P < 0.01). In the Cox proportional analysis adjusted for age and sex, eGFRcys, but not eGFRcreat and eGFR-EPI, showed a significant association with all-cause mortality (per 15 mL·min⁻¹·1.73 m⁻² decrease: hazard ratio 1.40, 95% confidence interval 1.18–1.67).

Conclusions

This study revealed that eGFRcys showed lower values than eGFRcreat and eGFR-EPI and was significantly associated with all-cause mortality in the Japanese community-based population.

Cumulative exposure of TDF is associated with kidney tubulopathy whether it is currently used or discontinued

OBJECTIVE

Tenofovir disoproxil fumarate (TDF) increases the risk of kidney tubular dysfunction (KTD). This study was conducted to elucidate whether KTD persists after discontinuation of TDF.

DESIGN

A prospective cross-sectional study which enrolled 941 HIV-1-infected patients.

METHODS

KTD was predefined as the presence of at least two abnormalities among the five tubular markers (fractional excretion of phosphate, fractional excretion of uric acid, β2 microglobulinuria, N-acetyl-β-D-glucosaminidase, nondiabetic glycosuria). Logistic regression model was used to examine the association between KTD and cumulative TDF use, as well as current status of TDF use.

RESULTS

In total, 94% of study patients were men (median age 45, estimated glomerular filtration rate 75 ml/min per 1.73 m, CD4 575 cells/μl. About 98% were on antiretroviral therapy. In total, 64% of the patients ever used TDF and 39% currently used TDF. Twenty-nine percent used TDF for more than 5 years. KTD was diagnosed in 116 (12%) patients. In multivariate model, more than 5 years of TDF exposure and current TDF use [odds ratio (OR) 4.2, 95% confidence interval (CI) 2.37-7.56], more than 5 years and past TDF use (OR 2.4, 95% CI 1.09-5.33), less than 5 years and current TDF (OR 2.4, 95% CI 1.24-4.85), and less than 5 years and past TDF (OR 2.4, 95% CI 1.22-4.64) were all significantly associated with KTD, with never TDF use as reference. The results were the same using 4 and 3 years of exposure as the cutoff. However, with 2 years exposure, both less than 2 years and current TDF (OR 2.3, 95% CI 0.84-6.20) and less than 2 years and past TDF (OR 1.9, 95% CI 0.73-4.93) were not associated with KTD, whereas both more than 2 years and current TDF and more than 2 years and past TDF were associated.

CONCLUSION

The association between cumulative TDF use and KTD was strong and robust. The results of the study suggested that TDF-related KTD might persist after discontinuation of TDF if patients used TDF for more than 2 years.

Evaluating estimated glomerular filtration rates of creatinine and cystatin C for male patients with chronic spinal cord injury

STUDY DESIGN

Retrospective study OBJECTIVES: To compare the accuracy of estimated serum creatinine (Cre)-based glomerular filtration rates (eGFRcre) and serum cystatin C (CysC)-based eGFR (eGFRcys) for determining renal function in patients with spinal cord injury (SCI).

SETTING

Department of Urology, Tohoku Rosai Hospital, Japan METHODS: Male patients with SCI for longer than 5 years after injury were eligible for inclusion in this study. eGFRcre and eGFRcys were calculated using the following formulas: eGFRcre = 194 × Cre^-1.094 × age^-0.287; eGFRcys = (104 × CysC^-0.1019 × 0.996^age) - 8. The eGFRcre/eGFRcys ratio between 0.8 and 1.2 was considered to be equal, and a relationship between them was investigated. Demographic data, degree of spinal cord damage, management of bladder emptying, post-injury period, and ambulatory status were evaluated.

RESULTS

A total of 115 male patients were included. eGFRcre overestimated renal function in 87 (76%) patients with SCI compared with eGFRcys. On univariate analysis, renal function by eGFRcre was overestimated in patients with an eGFRcre of more than 60 ml min^-1 per 1.73 m² (P < 0.001), in non-ambulatory patients (P < 0.001) and, in patients with complete paralysis (P < 0.001). On multivariate analysis, an eGFRcre of more than 60 ml min^-1 per 1.73 m² (P < 0.001), non-ambulatory status (P < 0.001), complete paralysis (P = 0.17), and age (P < 0.001) were independent factors for overestimated renal function by eGFRcre.

CONCLUSIONS

eGFRcre overestimates renal function compared with eGFRcys. eGFRcys is beneficial, particularly in patients with an eGFRcre of more than 60 ml min^-1 per 1.73 m², in non-ambulatory patients, and in older patients with SCI.

Clinical benefits of using inulin clearance and cystatin C for determining glomerular filtration rate in HIV-1-infected individuals treated with dolutegravir

INTRODUCTION

Dolutegravir may inhibit creatinine transporters in renal tubules and elevate serum creatinine levels. We investigated the usefulness of glomerular filtration rate (GFR) measured using inulin clearance (Cin), creatinine clearance (Ccr), and estimated GFR based on both serum creatinine (eGFRcre) and serum cystatin C (eGFRcys).

PATIENTS & METHODS

HIV-1-infected Japanese patients with suppressed viremia and whose antiretroviral drug was switched to dolutegravir from other drugs were included (n = 108, Study 1). We compared eGFRcre and eGFRcys at the start and after 48 weeks of dolutegravir administration. For the patients providing consent, we measured Cin and Ccr (n = 15, Study 2). We assessed biases and accuracy and compared Cin with eGFRcre, eGFRcys, and Ccr.

RESULTS

There were no differences in serum cystatin C and eGFRcys between baseline and at 48 weeks. Moreover, eGFRcre was significantly less accurate (within 30% of measured GFR) than both eGFRcys and Ccr (40% accuracy compared to 93% and 93%, respectively). eGFRcys was significantly less biased than eGFRcre and Ccr (p < 0.0001, p = 0.00036, respectively). No significant difference between Cin and eGFRcys was observed. eGFRcys was significantly correlated with Cin (γ = 0.85, p < 0.0001).

CONCLUSIONS

eGFRcys provided the most precise estimate and most closely approximate Cin in HIV-1-infected Japanese patients with suppressed viremia treated with dolutegravir. We demonstrated clinical benefits of inulin clearance and eGFRcys. This is the first study performing inulin clearance for HIV-1-infected individuals and to show data for eGFRcys from a large cohort following a switch to dolutegravir from other antiretroviral agents.

Prevalence and factors associated with chronic kidney disease and end-stage renal disease in HIV-1-infected Asian patients in Tokyo

This single-center cross-sectional study determined the prevalence and factors associated with chronic kidney disease (CKD) and end-stage renal disease (ESRD) in HIV-1-infected Asian patients at the largest HIV clinic in Japan. HIV-1-infected patients who visited the clinic between September and December 2016 were analyzed. CKD was defined as estimated glomerular filtration rate of <60 ml/min/1.73 m² or proteinuria ≥1+, observed at least over three months. A logistic regression model was used to estimate the effects of various variables on CKD. The study included 1,990 patients; with 97% Asians, 34% aged of ≥50 years, and 94% had HIV-1 load <50 copies/ml. The median time from HIV-1 diagnosis to study enrollment and duration of ART were 9.1 years (IQR4.8–14.2) and 7.35 years (IQR3.28–12), respectively. CKD and ESRD were diagnosed in 256 (13%) and 9 (0.5%) patients, respectively. The prevalence of CKD was 18.6% for age 50–59, 28.5% for 60–69, and 47% for over 70. Older age, heavier body weight, diabetes mellitus, hypertension, and longer duration of ART, but not duration of TDF exposure, were associated with CKD. The traditional risk factors, rather than HIV-1-related variables, were associated with CKD, suggesting the importance of management of such comorbidities in maintenance of renal function.

Impact of estimated glomerular filtration rate based on plasma cystatin C and serum creatinine levels before allogeneic hematopoietic cell transplantation

BACKGROUND

No standard method for measuring renal function has been established in allogeneic hematopoietic cell transplantation (allo-HCT).

METHODS

We retrospectively analyzed 80 patients with hematological diseases who underwent allo-HCT at our center. We assessed renal function using creatinine clearance (Ccr), estimated glomerular filtration rate (eGFR) based on creatinine (eGFRcre), eGFR based on cystatin C (eGFRcys), and the average of eGFRcre and eGFRcys (eGFRave). We then evaluated the impact of pre-transplant renal function on the exacerbation of renal function and non-relapse mortality after transplantation.

RESULTS

There was a significant correlation between Ccr and eGFRcre, eGFRcys, and eGFRave. eGFRave best predicted the exacerbation of renal function according to the area under the receiver-operating characteristic curve. The cumulative incidence of renal function exacerbation at 1 year was higher in the lower eGFRave group (<90 ml/min/1.73 m²) than in the higher eGFRave group (≥90 ml/min/1.73 m²; 0.85 vs. 0.39, p < 0.001), which was confirmed by a multivariate analysis (HR 2.75, p = 0.001). A lower eGFRave value was a marginally significant factor for non-relapse mortality (HR 3.29, p = 0.076).

CONCLUSION

Among the four parameters, eGFRave best predicted the exacerbation of renal function in allo-HCT. Further, the marginal association between low eGFRave and high non-relapse mortality warrants further study in a prospective study in allo-HCT.

Effect of Tenofovir Disoproxil Fumarate on Incidence of Chronic Kidney Disease and Rate of Estimated Glomerular Filtration Rate Decrement in HIV-1-Infected Treatment-Naïve Asian Patients: Results from 12-Year Observational Cohort

Little evidence is available for the incidence of chronic kidney disease (CKD) and rate of estimated glomerular filtration rate (eGFR) decrement among Asians with low body weight who are susceptible to tenofovir disoproxil fumarate (TDF) nephrotoxicity. In this 12-year observational cohort in Tokyo, we examined 1383 treatment-naïve HIV-1-infected Asians [720 started TDF-containing (TDF group) and 663 started non-TDF-containing (control) combination antiretroviral therapy (cART)]. The CKD incidence was calculated, and the effect of TDF use on CKD development was estimated using logistic regression. The eGFR slopes, before and after cART initiation, were estimated using mixed-effects linear spline models. Most patients were males (median weight, 62.6 kg; 83% started ritonavir-boosted protease inhibitors; median observation duration, 5.08 years). CKD developed in 150 patients (10.8%), with an incidence of 20.6 per 1000 person-years [confidence interval (95% CI), 17.6–24.2]. None developed end-stage renal disease. TDF use was associated with CKD [odds ratio (OR), 1.8; 95% CI, 1.00–3.13; p = 0.052]. The cumulative mean loss in the TDF group, relative to the control, increased over time after 1, 4, and 8 years of TDF exposure (−3.8, −5.5, and −9.0 mL/min/1.73 m², respectively; p < 0.0001). The eGFR rapidly declined during the first 3 months of cART, particularly in the TDF group (−26.4 vs. −7.4 mL/min/1.73 m²/year in the control). In the TDF group, cART introduction was significantly associated with a faster rate of eGFR decline (from −0.44 to −2.11 mL/min/1.73 m²/year; p = 0.010), whereas in the control, the difference was not significant. For HIV-1-infected Asian patients with low body weight, TDF-containing cART is associated with CKD and faster eGFR declines.

Comparison of cystatin C- and creatinine-based estimated glomerular filtration rates for predicting all-cause mortality in Japanese patients with type 2 diabetes: the Fukuoka Diabetes Registry

BACKGROUND

There is little information about the predictive ability of cystatin C-based estimated glomerular filtration rates (eGFR_Cys) for all-cause mortality in Asian populations. We compared the discriminatory ability of eGFR_Cys for all-cause mortality with that of creatinine-based estimated glomerular filtration rates (eGFR_Cr) in Japanese patients with type 2 diabetes.

METHODS

A total of 4869 participants were classified into four categories (eGFR ≤29, 30-59, 60-89, and ≥90 ml/min/1.73 m²) by eGFR_Cr and eGFR_Cys, and followed up for a median of 3.3 years.

RESULTS

150 deaths were identified. The multivariable-adjusted risk of all-cause mortality was significantly increased in eGFR_Cr ≤29 ml/min/1.73 m² compared with eGFR_Cr ≥90 ml/min/1.73 m² [hazard ratio (HR) 2.4 (95 % confidence interval (95 % CI) 1.2-5.0)], whereas it was significantly increased in eGFR_Cys 59 ml/min/1.73 m² or lower [30-59 ml/min/1.73 m², HR 1.9 (95 % CI 1.1-3.5); ≤29 ml/min/1.73 m², HR 5.8 (95 % CI 2.8-12.0)]. Comparing eGFR_Cys with eGFR_Cr, the proportions of participants reclassified to lower and higher eGFR stages were 6.3 and 28.8 %, respectively. The multivariable-adjusted HRs for all-cause mortality were 1.8 (95 % CI 1.1-2.9) and 0.7 (95 % CI 0.4-1.1), respectively. The C statistic of the model including eGFR_Cys and other risk factors was significantly increased compared with the model including eGFR_Cr. The net reclassification improvement and the integrated discrimination improvement were significantly positive.

CONCLUSIONS

Our findings suggest that eGFR_Cys has a stronger association with all-cause mortality and is superior to eGFR_Cr for predicting all-cause mortality in Japanese patients with type 2 diabetes.

Effects of smoking and its cessation on creatinine- and cystatin C-based estimated glomerular filtration rates and albuminuria in male patients with type 2 diabetes mellitus: the Fukuoka Diabetes Registry

Cigarette smoking is an important modifiable risk factor for lifestyle diseases. The smoking rate remains high, and the prevalence of diabetes mellitus is increasing in Asian countries; however, few studies have examined the effects of smoking on chronic kidney disease (CKD) in Asian diabetic patients. The aim of the present study was to investigate the association between smoking and its cessation with CKD and its components in patients with type 2 diabetes. A total of 2770 Japanese male patients with type 2 diabetes aged ⩾20 years were divided according to the amount of cigarette smoking and the years since cessation. The associations with CKD, the urinary albumin-creatinine ratio (UACR) and the estimated glomerular filtration rate (eGFR) were cross-sectionally examined. The proportions of CKD and the mean UACR dose-dependently increased with increases in both the number of cigarettes per day and the Brinkman index compared with the never smokers. The creatinine-based eGFR also increased with increases in the amount of smoking, whereas the cystatin C-based eGFR decreased, and their average did not significantly change. These parameters exhibited inverse associations with the years after smoking cessation compared with the association with the amount of smoking. A dose-dependent association of active smoking and a graded inverse association of the years since quitting with CKD enhance the merit of smoking cessation in patients with type 2 diabetes.

Drug Transporter Genetic Variants Are Not Associated with TDF-Related Renal Dysfunction in Patients with HIV-1 Infection: A Pharmacogenetic Study

Objective

To investigate whether single nucleotide polymorphisms (SNP) of drug transporter proteins for TDF is a risk factor for TDF-related renal function decrement.

Methods

This study investigated the association between 3 SNPs (ABCC2–24, 1249, and ABCB1 2677), which are shown to be associated with TDF-induced tubulopathy, and clinically important renal outcomes (>10ml/min/1.73m² decrement in eGFR relative to baseline, >25% decrement in eGFR, and eGFR <60ml/min/1.73m²) in 703 HIV-1-infected Japanese patients who initiated TDF-containing antiretroviral therapy (ART). Genotyping was performed by allelic discrimination using TaqMan 5’-nuclease assays.

Results

95% of the study patients were males and 66% were treatment-naïve, with median CD4 count of 249/μl, median baseline eGFR of 96ml/min/1.73m² (IQR 84.6–109.2), and median exposure to TDF of 3.66 years (IQR 1.93–5.59). The frequencies of genotypes at -24, 1249 of ABCC2, and 2677 of ABCB1 were neither different between patients with decrement in eGFR of >10ml/min/1.73m² and those without such decrement (ABCC2: -24, p = 0.53, 1249, p = 0.68; ABCB1: 2677, p = 0.74), nor between those without and with the other two renal outcomes (>25% decrement: ABCC2: -24, p = 0.83, 1249, p = 0.97, ABCB1: 2677, p = 0.40; eGFR <60ml/min/1.73m²: ABCC2: -24, p = 0.51, 1249, p = 0.81, ABCB1: 2677, p = 0.94). Logistic regression analysis showed that the risk genotype of the three SNPs were not associated with any of the three renal outcomes, respectively. Logistic regression model that applied either dominant, recessive, or additive model yielded the same results.

Conclusions

SNPs of the drug transporters for TDF are not associated with clinically important renal outcomes in patients who initiated TDF-containing ART.

Renal function evaluation in patients with cancer who were scheduled to receive carboplatin or S-1

BACKGROUND

Accurate glomerular filtration rate (GFR) evaluation is significant for drug dosing of carboplatin, anticancer drug excreted mainly from kidney. Serum cystatin-C (sCys-C) is a GFR marker with little affected by body muscle mass volume. And GFR equations based on serum creatinine (eGFRcreat) and sCys-C (eGFRcys) were developed; however, accuracy of eGFRcys has not been elucidated fully among patients with cancer. Therefore, we analyzed the performance of GFR equations among patients with cancer whose GFR values were measured by inulin clearance (Cin).

METHODS

Study design was a cross-sectional study. Subjects were 41 patients with cancer whose GFR values were measured by Cin for drug dosing studies of carboplatin or S-1 in Nagoya University Hospital from 2007 to 2010 and 29 non-cancer patients. Correlation with Cin and slope of regression line were evaluated in eGFRcreat and eGFRcys. Single and multiple regression analyses were analyzed to identify associating factors with eGFRcreat/Cin or eGFRcys/Cin.

RESULTS

Age, body weight, body mass index (BMI) and sCr were different between cancer patients and non-cancer patients, but sCys-C and Cin were consistent in 2 groups. The slope of the regression line for Cin vs. eGFRcys with zero intercept in cancer patients was 1.10 (95 % CI: 1.02-1.17), which was significantly different from 1.0. In multiple regression analysis revealed that BMI and urinary creatinine excretion were significantly associated with eGFRcreat/Cin, and cancer was only associating factor with eGFRcys/Cin.

CONCLUSION

eGFRcys should not be used for evaluation of renal function in patients with cancer because it underestimates GFR.

Comparison of cystatin C- and creatinine-based estimated glomerular filtration rate to predict coronary heart disease risk in Japanese patients with obesity and diabetes

The aim of this study is to determine which indicator of chronic kidney disease most closely correlates with 10-year Framingham coronary heart disease (CHD) risk among serum creatinine, serum cystatin C (S-CysC), urine albumin-creatinine ratio (UACR), estimated creatinine-based GFRs (eGFRcre), and estimated CysC-based GFRs (eGFRcys) in patients with obesity and diabetes. Serum creatinine, S-CysC, UACR, and cardio-ankle vascular index (CAVI) were examined in 468 outpatients with obesity and type 2 diabetes, free of severe renal dysfunction or previous history of cardiovascular disease, as a cross-sectional survey using baseline data from the multi-centered Japan Diabetes and Obesity Study. S-CysC and eGFRcys had significantly stronger correlations with the 10-year Framingham CHD risk than serum creatinine, eGFRcre, and UACR (creatinine, ρ = 0.318; S-CysC, ρ = 0.497; UACR, ρ = 0.174; eGFRcre, ρ = -0.291; eGFRcys, ρ = -0.521; P < 0.01 by Fisher's z-test). S-CysC and eGFRcys had significantly stronger correlations with CAVI than serum creatinine, eGFRcre, and UACR (creatinine, ρ = 0.198; S-CysC, ρ = 0.383; UACR, ρ = 0.183; eGFRcre, ρ = -0.302; eGFRcys, ρ = -0.444; P < 0.05 by Fisher's z-test). The receiver operating characteristic curves to distinguish the high-risk patients for CHD revealed significantly larger areas under the curve of S-CysC and eGFRcys than those of serum creatinine, UACR, and eGFRcre (serum creatinine, 0.64; S-CysC, 0.75; UACR, 0.56; eGFRcre, 0.63; eGFRcys, 0.76; P < 0.01). The data suggested that eGFRcys can be more predictive of the 10-year CHD risk than eGFRcre in Japanese patients with obesity and diabetes.

Long-term exposure to tenofovir continuously decrease renal function in HIV-1-infected patients with low body weight: results from 10 years of follow-up

OBJECTIVES

To investigate the effect of long-term tenofovir disoproxil fumarate (TDF) use on renal function, especially in patients with low body weight who are vulnerable to TDF nephrotoxicity.

DESIGN

A single-center, observational study in Tokyo, Japan.

METHODS

We performed a 10 years cohort study of 792 HIV-1-infected patients. The effect of long-term TDF use on estimated glomerular filtration rate (eGFR) was investigated on treatment-naive patients who started TDF-containing antiretroviral therapy (n = 422) and those who started abacavir-containing antiretroviral therapy as control (n = 370). Three renal endpoints were examined by the logistic regression model: decrement in eGFR of higher than 10 ml/min per 1.73 m relative to the baseline, more than 25% decrement in eGFR, and eGFR lower than 60 ml/min per 1.73 m at least 3 months apart. The loss in eGFR was estimated using linear mixed models for repeated measures.

RESULTS

The median weight at baseline was 63 kg. TDF use increased the risk of all three renal outcomes compared with the control group: higher than 10 ml/min per 1.73 m decrement in eGFR [adjusted odds ratio (OR) = 2.1, 95% confidence interval (CI) 1.45-3.14, P < 0.001], more than 25% decrement (adjusted OR = 2.1, 95% CI 1.50-2.90, P < 0.001), and eGFR lower than 60 ml/min per 1.73 m at least 3 months apart (adjusted OR = 3.9, 95% CI 1.62-9.36, P = 0.002). The cumulative mean loss relative to the control after 1, 2, 3, 4, and 5 years of TDF exposure was -3.8, -3.6, -5.5, -6.6, and -10.3 ml/min per 1.73 m, respectively, indicating that the loss in eGFR increased over time (P < 0.001).

CONCLUSION

In this cohort of patients with low body weight, TDF exposure increased the risk of renal dysfunction. Furthermore, the loss in eGFR relative to the control increased continuously up to 5 years.

Poor glycemic control is a major factor in the overestimation of glomerular filtration rate in diabetic patients

OBJECTIVE Serum creatinine levels are lower in diabetic patients compared with their nondiabetic counterparts. Therefore, estimated glomerular filtration rate (eGFR) is higher in the former than in the latter group. Factors associated with overestimation of renal function in diabetic patients were examined, and new formulae reflecting precise eGFR were created. RESEARCH DESIGN AND METHODS Eighty subjects (age 56.5 ± 15.4 years; 35 males [43.8%]; 40 patients with diabetes and 40 nondiabetic subjects) were enrolled. GFR was evaluated by inulin clearance (Cin). eGFR values were calculated based on serum creatinine and/or serum cystatin C levels. The factors related to the dissociation between eGFR and Cin in diabetic patients and the agreement among each of three eGFR and Cin were compared. RESULTS Although Cin was not significantly different between the diabetic and nondiabetic subjects (P = 0.2866), each of three eGFR measures from the diabetic patients was significantly higher than that of the nondiabetic subjects (P < 0.01). There were significant and positive correlations between the ratio of each eGFR/Cin, hemoglobin A1c, and glycated albumin. The intraclass correlation coefficients in diabetic patients were weaker than those in the nondiabetic subjects, and the intercepts of the regression lines between each eGFR measure and Cin in the diabetic patients were significantly higher than those of the nondiabetic subjects. New formulae for the calculation of eGFR corrected by the glycemic control indices were better than the original eGFR, particularly in diabetic patients. CONCLUSIONS eGFR overestimates Cin as glycemic controls worsen. eGFR corrected by hemoglobin A1c is considered to be clinically useful and feasible.

Renal prognosis a long time after renal biopsy on patients with diabetic nephropathy

BACKGROUND

A new classification of diabetic nephropathy was reported by Tervaert et al., but the association between pathological findings and the clinical outcomes remains unclear.

METHODS

Among 310 patients with diabetes mellitus who underwent renal biopsy from March 1985 to January 2010 and were confirmed to have diabetic nephropathy according to the Tervaert's classification, 205 patients were enrolled in this study. Cox proportional hazard regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI) for death-censored renal death. Each regression analysis employed two levels of multivariate adjustment.

RESULTS

After adjustment for age, gender, estimated glomerular filtration rate, type of diabetes, urinary protein excretion, systolic blood pressure, body mass index, HbA1c, diabetic retinopathy and red blood cells in urinary sediment at the time of renal biopsy, compared with glomerular class IIA, the HRs for death-censored renal death of glomerular classes I, IIB, III and IV were 0.21 (95% CI: 0.04-1.25), 2.12 (0.89-5.04), 4.23 (1.80-9.90), and 3.27 (1.32-8.10), respectively. Also, compared with an interstitial fibrosis and tubular atrophy score 1 group, HRs for score 0 group, score 2 group and score 3 group were 0.08 (0.01-0.57), 2.17 (0.96-4.91), 4.78 (1.96-11.68), respectively.

CONCLUSIONS

The progression of glomerular, tubulointerstitial and vascular lesions was associated with higher HRs for renal death. These results suggest the clinical utility of Tervaert's pathological classification.

T/L-type calcium channel blocker reduces the composite ranking of relative risk according to new KDIGO guidelines in patients with chronic kidney disease

BACKGROUND

Recently, the Kidney Disease: Improving Global Outcomes (KDIGO) group recommended that patients with chronic kidney disease (CKD) be assigned according to stage and composite relative risk on the basis of glomerular filtration rate (GFR) and albuminuria criteria. The aim of this post-hoc analysis was to investigate the effects of add-on therapy with calcium channel blockers (CCBs) on changes in the composite ranking of relative risk according to KDIGO guidelines. Benidipine, an L- and T-type CCB, and amlodipine, an L-type CCB to angiotensin II receptor blocker (ARB), were examined.

METHODS

Patients with blood pressure (BP) > 130/80 mmHg, an estimated GFR (eGFR) of 30-90 mL/min/1.73 m2, and albuminuria > 30 mg/gCr, despite treatment with the maximum recommended dose of ARB, were randomly assigned to two groups. Each group received one of two treatments: 2 mg benidipine daily, increased to 8 mg daily (n = 52), or 2.5 mg amlodipine daily, increased to 10 mg daily (n = 52).

RESULTS

After 6 months of treatment, a significant and comparable reduction in systolic and diastolic BP was observed in both groups. The eGFR was significantly decreased in the amlodipine group, but there was no significant change in the benidipine group. The decrease in albuminuria in the benidipine group was significantly lower than in the amlodipine group. The composite ranking of relative risk according to the new KDIGO guidelines was significantly improved in the benidipine group; however, no significant change was noted in the amlodipine group. Moreover, significantly fewer cases in the benidipine group than the amlodipine group showed a reduced risk category score.

CONCLUSION

The present post-hoc analysis showed that compared to amlodipine benidipine results in a greater reduction in albuminuria accompanied by an improved composite ranking of relative risk according to the KDIGO CKD severity classification.

TRIAL REGISTRATION

TRIAL REGISTRATION NUMBER

UMIN000002644.