Comparing Results of Five Glomerular Filtration Rate-Estimating Equations in the Korean General Population: MDRD Study, Revised Lund-Malmö, and Three CKD-EPI Equations

Urinary peptide analysis to predict the response to blood pressure medication

BACKGROUND

The risk of diabetic kidney disease (DKD) progression is significant despite treatment with renin-angiotensin system (RAS) blocking agents. Current clinical tools cannot predict whether or not patients will respond to treatment with RAS inhibitors (RASi). We aimed to investigate whether proteome analysis could identify urinary peptides as biomarkers that could predict the response to angiotensin-converting enzyme inhibitor and angiotensin-receptor blockers treatment to avoid DKD progression. Furthermore, we investigated the comparability of the estimated glomerular filtration rate (eGFR), calculated using four different GFR equations, for DKD progression.

METHODS

We evaluated urine samples from a discovery cohort of 199 diabetic patients treated with RASi. DKD progression was defined based on eGFR percentage slope results between visits (∼1 year) and for the entire period (∼3 years) based on the eGFR values of each GFR equation. Urine samples were analysed using capillary electrophoresis-coupled mass spectrometry. Statistical analysis was performed between the uncontrolled (patients who did not respond to RASi treatment) and controlled kidney function groups (patients who responded to the RASi treatment). Peptides were combined in a support vector machine-based model. The area under the receiver operating characteristic curve was used to evaluate the risk prediction models in two independent validation cohorts treated with RASi.

RESULTS

The classification of patients into uncontrolled and controlled kidney function varies depending on the GFR equation used, despite the same sample set. We identified 227 peptides showing nominal significant difference and consistent fold changes between uncontrolled and controlled patients in at least three methods of eGFR calculation. These included fragments of collagens, alpha-1-antitrypsin, antithrombin-III, CD99 antigen and uromodulin. A model based on 189 of 227 peptides (DKDp189) showed a significant prediction of non-response to the treatment/DKD progression in two independent cohorts.

CONCLUSIONS

The DKDp189 model demonstrates potential as a predictive tool for guiding treatment with RASi in diabetic patients.

Application of the European Kidney Function Consortium Equation to Estimate Glomerular Filtration Rate: A Comparison Study of the CKiD and CKD-EPI Equations Using the Korea National Health and Nutrition Examination Survey (KNHANES 2008-2021)

Background and Objectives: The European Kidney Function Consortium (EKFC) equation has been newly proposed for estimating glomerular filtration rate (eGFR) across the spectrum of age. We compared the EKFC equation with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in a large-scale Korean population. Materials and Methods: Using the representative Korean health examination data, the Korea National Health and Nutrition Examination Survey (KNHANES 2008-2021), the records of 91,928 subjects (including 9917 children) were analyzed. We compared the EKFC equation with CKiD, CKD-EPI 2009, and CKD-EPI 2021 equations and investigated their agreement across GFR categories. Results: In the total population, the CKD-EPI 2021 equation yielded the highest eGFR value, followed by the CKD-EPI 2009 and EKFC equations. In children, the distribution of eGFR differed significantly between the EKFC and CKiD equations (p < 0.001), with a wider range of eGFR values found with the CKiD equation. Each equation showed weak or moderate agreement on the frequency of the GFR category (κ = 0.54 between EKFC and CKD-EPI 2021; κ = 0.77 between EKFC and CKD-EPI 2009). The eGFR values found by the EKFC equation showed high or very high correlations with those by the CKiD, CKD-EPI 2009, and CKD-EPI 2021 equations (r = 0.85, 0.97, and 0.97, respectively). As eGFR values increased, bigger differences were observed between equations. Conclusions: This large-scale study demonstrates that the EKFC equation would be applicable across the entire age spectrum in Asian populations. It also underscores that national kidney health would be highly affected by an eGFR equation being implemented. Additional investigation and more caution would be warranted for the transition of eGFR equations.

Comparison of EKFC, Pakistani CKD-EPI and 2021 Race-Free CKD-EPI creatinine equations in South Asian CKD population: A study from Pakistani CKD community cohort

INTRODUCTION

South Asian individuals possess a high risk of chronic kidney disease. There is a need to study, evaluate, and compare the newly suggested glomerular filtration rate (eGFR) equations for accurate CKD diagnosis, staging, and drug dosing. This study aimed to (1) evaluate the European Kidney Function Consortium (EKFC), Pakistani CKD-EPI, and 2021 Race-Free CKD-EPI creatinine equation in the South Asian population with CKD and (2) to examine the expected implications on both CKD classification as well as End Stage Renal Disease (ESRD) prevalence across these equations in South Asian population.

METHODS

We carried out a cross-sectional investigation on 385 participants, a CKD cohort ≥ 18 years, at Allama Iqbal Medical College, Jinnah Hospital, Lahore. Serum creatinine was measured by Jaffe's method and rGFR was measured by inulin clearance.

RESULTS

Pakistani CKD-EPI has a lower median difference at -1.33 ml/min/1.73m2 elevated precision (IQR) at 2.33 (-2.36, -0.03) and higher P30 value at 89.35% than 2021 CKD-EPI and EKFC equations. The mean difference (ml/min/1.73m2), 95% agreement limits (ml/min/1.73m2) of CKD-EPI PK: -1.18, -6.14, 2021 CKD-EPI: -5.98, -13.24 and EKFC: -5.62, -13.01 (P <0.001). These equations highly correlated to rGFR (P <0.001). An upward re-classification in GFR categories was shown by 2021 CKD-EPI and EKFC compared to the Pakistani CKD-EPI equation. However, there was an exception regarding the G5 category, where an elevated count of 217 (56.36%) was shown for CKD-EPI PK. The prevalence of ESRD was seen in entire age groups and prevailed among females more than in males overall equations.

CONCLUSIONS

Pakistani CKD-EPI exhibited outstanding performance, while 2021 CKD-EPI and EKFC demonstrated poor performances and could not show an adequate advantage for both CKD classification and prevalence of ESRD compared to Pakistani CKD-EPI. Therefore, Pakistani CKD-EPI appears optimal for this region and warrants future validation in other South Asian countries. In contrast, suitable measures must be implemented in Pakistani laboratories.

Post Liver Transplant Renal Dysfunction-Evaluation, Management and Immunosuppressive Practice

Liver transplantation (LT) is an effective and lifesaving treatment for patients with end-stage liver disease and hepatocellular carcinoma. Significant improvement in intermediate and long-term survival has been possible due to advancements in immunosuppressive therapy, perioperative care, and surgical techniques. Despite these advances, metabolic complications, including diabetes mellitus, cardiovascular diseases, malignancies, and renal dysfunction, are challenging issues after LT. Acute kidney injury (AKI) and chronic kidney disease (CKD) after LT are common and result in significant morbidity and mortality. Early diagnosis of kidney injury after LT is challenging, and no technique has yet proven effective in prediction of renal dysfunction. The methods for assessing renal function range from formulas that predict glomerular filtration rate to non-invasive biomarkers. The universal adoption of the model for end-stage liver disease has a direct impact on the incidence of peri-transplant AKI and development of CKD in the long-term. Post-LT renal dysfunction is multifactorial and is usually a result of pre-transplantation comorbidities, occurrence of renal dysfunction on the waiting list, perioperative events, and post-transplant nephrotoxic immunosuppressive medication use. Early identification of patients at risk for renal dysfunction and adoption of preventive measures are crucial in the pre-transplant period. No data are currently available to suggest a surgical technique that reliably demonstrates renal protection. Nephroprotective strategies during LT follow accepted surgical practice guidelines, such as maintenance of intravascular volume and mean arterial pressure. The management of kidney disease following LT is challenging, as by the time the serum creatinine is significantly elevated, few interventions impact the course of progression. Early nephroprotective measures are strongly advised and they mostly center on delaying the administration of calcineurin inhibitors (CNIs) during the initial postoperative period, lowering CNI dosage and combining CNI with mycophenolate mofetil and everolimus. The reasons for renal failure following LT, the techniques used to diagnose it, and the therapies designed to preserve renal function both immediately and late after LT are all critically evaluated in this review.

Comparison of Pakistani CKD-EPI, new Asian-modified CKD-EPI and revised Lund-Malmö study equations in a South Asian CKD population: a study from a Pakistani CKD cohort

BACKGROUND

Newly proposed estimating glomerular filtration rate equations need to be studied, evaluated and compared for chronic kidney disease staging, diagnosis and medication dosing in South Asians. The objectives of the study were (1) to assess the performance of the CKD-EPIPK, CKD-EPIAsian-Modified, and LMRevised equations in the Pakistani chronic kidney disease population, and (2) to investigate prospective implications on chronic kidney disease classification and end-stage kidney disease prevalence.

METHODS

We conducted a cross-sectional analysis on a chronic kidney disease cohort of 385 participants 18 years of age or above.

RESULTS

CKD-EPIPK showed the lowest bias (- 1.33 ml/min/1.73 m2), highest precision [IQR, 2.33 (- 2.36, - 0.03)] and enhanced P30 accuracy (89.35%) compared to the CKD-EPIAsian-Modified and LMRevised equations. The mean difference (ml/min/1.73 m2), 95% limit of agreement (ml/min/1.73 m2) of the equations were; CKD-EPIAsian-Modified: - 5.98, - 13.03, LMRevised: - 4.06, - 8.13 and CKD-EPIPK: - 1.18, - 6.14 (P < 0.001). CKD-EPIAsian-Modified and LMRevised showed upward re-classification of the GFR categories compared to the CKD-EPIPK equation except in the G5 category where the highest count (217, 56.36%) was noted for the CKD-EPIPK equation. End-stage kidney disease prevailed in all age groups according to all equations, and the prevalence was high in females in all equations.

CONCLUSION

CKD-EPIPK showed the best performance, whereas both CKD-EPIAsian-Modified and LMRevised showed poor performance and did not offer a sufficient advantage in chronic kidney disease classification and end-stage kidney disease prevalence estimation over CKD-EPIPK. Hence, CKD-EPIPK seems ideal for South Asians, thus appropriate measures should be taken for its implementation, at least in Pakistani laboratories.

European Kidney Function Consortium Equation vs. Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) Refit Equations for Estimating Glomerular Filtration Rate: Comparison with CKD-EPI Equations in the Korean Population

The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation is the most commonly used equation for estimated glomerular filtration rate (eGFR). Recently, the European Kidney Function Consortium (EKFC) announced a full-age spectrum equation, and the CKD-EPI announced the CKD-EPI refit equations (CKD-EPI-R). We compared CKD-EPI, EKFC, and CKD-EPI-R equations in a large-scale Korean population and investigated their potential implications for CKD prevalence. In a total of 106,021 individuals who received annual check-ups from 2018 to 2020, we compared the eGFR equations according to the Clinical and Laboratory Standards Institute guidelines. Weighted kappa (κ) agreement was used to compare the potential implications for CKD prevalence across the equations. The median value of eGFR tended to increase in the order of EKFC, CKD-EPI, and CKD-EPI-R equations (92.4 mL/min/1.73 m², 96.0 mL/min/1.73 m², and 100.0 mL/min/1.73 m², respectively). The EKFC and CKD-EPI-R equations showed a very high correlation of eGFR and good agreement for CKD prevalence with CKD-EPI equation (r = 0.98 and 1.00; κ = 0.80 and 0.82, respectively). Compared with the CKD-EPI equation, the EFKC equation overestimated CKD prevalence (3.5%), and the CKD-EPI-R equation underestimated it (1.5%). This is the first study comparing CKD-EPI, EKFC, and CKD-EPI-R equations simultaneously. The EKFC and CKD-EPI-R equations were statistically interchangeable with CKD-EPI equations in this large-scale Korean population. The transition of eGFR equations, however, would lead to sizable changes in the CKD prevalence. To improve kidney health, in-depth discussion considering various clinical aspects is imperative for the transition of eGFR equations.

Comparison of four equations for estimation of glomerular filtration rate in predicting cardiovascular events and subclinical vascular disease in patients with type-2 diabetes

AIMS

Chronic kidney disease (CKD), defined by a low glomerular filtration rate (GFR), is a predictor of cardiovascular disease in patients with type-2 diabetes (T2D). We aimed to compare four GFR equations in predicting future cardiovascular events in T2D and the presence of subclinical vascular disease.

METHODS

Four equations were used to estimate GFR in asymptomatic T2D patients consulting our centre for cardiovascular assessment. Follow-up was performed to collect cardiovascular events. Cox proportional hazard ratio (HR) was used to build and compare prediction models, and the incremental value of the addition of GFR with any of the 4 formulas was evaluated. The ability to triage patients with and without CVD events according to GFR were assessed by comparing the receiver operator characteristics (ROC) curves with the 4 models.

RESULTS

Among 829 asymptomatic T2D patients, the CKD prevalence was 20.2% for Modification of Diet in Renal Disease (MDRD), 17.3% for Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), 20.7% for Lund-Malmö Revised (LMR) and 21.4% for Full Age Spectrum (FAS). All the estimated GFRs were well correlated from one formula to another, with stronger agreement to define CKD (GFR <60 mL/min/1.73 m²) between MDRD and CKD-EPI, and between LMR and FAS. The 5-year incidence of cardiovascular events was 8% (n = 63). After adjustment on covariables, CKD was significantly associated with cardiovascular events when defined by MDRD (HR = 2.04; 1.15-3.60) and CKD-EPI (HR = 1.90; 1.05-3.41) but missed statistical significance when using LMR (HR = 1.74; 0.97-3.14) or FAS (HR = 1.71; 0.94-3.14). Only the prediction models including MDRD and CKD-EPI provided a significant incremental information to the predictive model without GFR, but the area under the ROC curves were similar with the 4 models: 0.60 [0.54-0.68] for MDRD, 0.61 [0.49-0.65] for CKD-EPI and 0.62 [0.55-0.69] for LMR and FAS, without any significant difference among formulas.

CONCLUSION

In asymptomatic T2D patients, MDRD and CKD-EPI may be preferable when more specificity is desired (stronger association between GFR and CVD events), while LMR and FAS appear more sensitive by including a higher number of patients with GFR <60 mL/min/1.73 m².

Correlation of Glomerular Size With Donor-Recipient Factors and With Response to Injury

BACKGROUND

Glomerular size in renal allografts is impacted by donor-recipient factors and response to injury. In serial biopsies of patients with well-functioning grafts, increased glomerular size correlates with better survival. However, no previous study has addressed the association of glomerular size at the time of a for-cause biopsy and clinical/histopathologic markers of injury, or effect on long-term graft outcome.

METHODS

Two cohorts of kidney transplant recipients enrolled in the Deterioration of Kidney Allograft Function study were evaluated. The prospective cohort (PC, n = 581): patients undergoing first for-cause kidney biopsy 1.7 ± 1.4 (mean ± SD) y posttransplant; and the cross-sectional cohort (CSC, n = 446): patients developing new-onset renal function deterioration 7.7 ± 5.6 y posttransplant. Glomerular planar surface area and diameter were measured on all glomeruli containing a vascular pole. Kidney biopsy was read centrally in a blinded fashion according to the Banff criteria.

RESULTS

Glomerular area was significantly higher in the CSC than the PC; time from transplant to indication biopsy was associated with glomerular area in both cohorts (P values ≤ 0.001). Glomerular area was associated with indices of microvascular inflammation (glomerulitis, peritubular capillary infiltrates; P values ≤ 0.001) and segmental glomerulosclerosis (P value < 0.0001). In the CSC, higher glomerular area was associated with higher estimated glomerular filtration rate (P value ≤ 0.001) and increased graft survival after accounting for microvascular inflammation (adjusted hazard ratio = 0.967; 95% confidence interval: 0.948-0.986; hazard ratio in biopsies without evidence of diabetes or antibody mediated rejection = 0.919, 95% confidence interval: 0.856-0.987).

CONCLUSIONS

Glomerular size is associated with histopathologic features present at the time of indication biopsy and with increased graft survival in the CSC.

Biomarker-Guided Risk Assessment for Acute Kidney Injury: Time for Clinical Implementation?

Acute kidney injury (AKI) is a common and serious complication in hospitalized patients, which continues to pose a clinical challenge for treating physicians. The most recent Kidney Disease Improving Global Outcomes practice guidelines for AKI have restated the importance of earliest possible detection of AKI and adjusting treatment accordingly. Since the emergence of initial studies examining the use of neutrophil gelatinase-associated lipocalin (NGAL) and cycle arrest biomarkers, tissue inhibitor metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein (IGFBP7), for early diagnosis of AKI, a vast number of studies have investigated the accuracy and additional clinical benefits of these biomarkers. As proposed by the Acute Dialysis Quality Initiative, new AKI diagnostic criteria should equally utilize glomerular function and tubular injury markers for AKI diagnosis. In addition to refining our capabilities in kidney risk prediction with kidney injury biomarkers, structural disorder phenotypes referred to as "preclinical-" and "subclinical AKI" have been described and are increasingly recognized. Additionally, positive biomarker test findings were found to provide prognostic information regardless of an acute decline in renal function (positive serum creatinine criteria). We summarize and discuss the recent findings focusing on two of the most promising and clinically available kidney injury biomarkers, NGAL and cell cycle arrest markers, in the context of AKI phenotypes. Finally, we draw conclusions regarding the clinical implications for kidney risk prediction.

The ideal marker for measuring GFR: what are we looking for?

Introduction:

The most accurate way of assessing kidney function is the measurement of the glomerular filtration rate (GFR). Since, we do not have good formulae to estimate GFR in elderly, in this study we evaluate the accuracy of the most commonly used formulas for the estimation of GFR in comparison with direct measurement in elderly.

Materials and Methods:

85 patients (51 males and 34 females), with an average age of 76.2 ± 4.4 years, 42% already diagnosed with chronic kidney disease (CKD) were investigated. Two plasma samples were collected between 60-90 and 165-195 minutes after injection of ^99mTc-DTPA, and the GFR was calculated applying Charles D. Russell’s two-sample method.

Results:

When comparing the GFR values obtained from the various formulae by creatinine levels with the GFR values obtained by measuring ^99mTc-DTPA residue, the following concordance values emerged: (1) MDRD: 57.5 ± 9.59 %; (2) Cockroft-Gault: 48.33 ± 24.93; (3) CKD-EPI: 49.40 ± 26.30; (4) BIS1: 58 ± 6.79.

Conclusion:

Our data shows a greater concordance between the GFR values calculated with the Russell’s method and the estimated values of GFR when the latter are calculated using the MDRD or BIS1 formulae. (www.actabiomedica.it)

Perturbed Beta-Cell Function and Lipid Profile After Early Prenatal Dexamethasone Exposure in Individuals Without CAH

BACKGROUND

Prenatal treatment with dexamethasone (DEX) reduces virilization in girls with congenital adrenal hyperplasia (CAH). The treatment is effective but may result in long-lasting adverse effects. In this study we explore the effects of DEX on metabolism in individuals not having CAH but treated with DEX during the first trimester of fetal life.

METHOD

All DEX-treated participants (n = 40, age range 5.1-26.4 years) and controls (n = 75, age range 4.5-26.6 years) were assessed with fasting blood samples to measure blood count, renal function, glucose homeostasis, and serum lipid profiles.

RESULTS

There were no significant differences between DEX and control participants for birth parameters, weight and height, or body mass index at the time of testing. Analyzing the entire cohort, we found no significant effects of DEX on blood count, renal function, or serum lipid profiles. However, a lower HOMA-β index in the DEX-treated individuals (U = 893.0; P = 0.049) was observed. Post hoc analyses revealed an effect in girls (U = 152.5; P = 0.024) but not in boys (U = 299.5; P = 0.550). The effect on HOMA-β persisted (U = 117.5; P = 0.048) after analyzing data separately in the participants < 16 years of age. In addition, we observed higher plasma glucose levels (F = 14.6; P = 0.001) in the DEX-treated group. The participants ≥ 16 years of age in the DEX-treated group had significantly higher total plasma cholesterol (F = 9.8; P = 0.003) and higher low-density lipoprotein cholesterol levels (F = 7.4; P = 0,009).

CONCLUSION

Prenatal DEX exposure in early pregnancy has negative effects on beta-cell function and lipid profile in individuals without CAH already at a young age.

Prognostic Values of Three Equations in Estimating Glomerular Filtration Rates of Patients Undergoing Off-Pump Coronary Artery Bypass Grafting

Background

Renal dysfunction is independently associated with both short-term and long-term mortality after coronary artery bypass grafting (CABG). The estimated glomerular filtration rate (eGFR) is a convenient and effective indicator of renal function. However, the ability of eGFR calculated by various equations to predict the outcomes of patients undergoing off-pump CABG (OPCABG) is still unclear. This study was aimed to compare the predictive ability of in-hospital and long-term mortality in three equations of estimating renal functions after OPCABG.

Methods

Totally, 1362 patients undergoing OPCABG were retrospectively reviewed. Preoperative and postoperative serum creatinine (Scr) levels were detected. The renal function was evaluated by the Cockcroft-Gault (CG) equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, and the full-age spectrum (FAS) equation. The endpoints were in-hospital and long-term all-cause mortality rates. Receiver operating characteristic curves, net reclassification index, decision curve analysis (DCA), multivariable logistic model, and Cox regression model were used for comparisons.

Results

The CG equation had the significantly highest discriminatory power to predict in-hospital mortality (area under the curve=0.815). Valuable clinical net benefits of the CG equation were greater than the other two equations regardless of before or after operation by DCA. Multivariable logistic and Cox regression analysis illustrated that the eGFR calculated by the CG equation was a significant independent risk factor of both in-hospital mortality (odds ratio=3.390) and long-term mortality (hazard ratio=1.553).

Conclusion

The CG equation outperformed the FAS and CKD-EPI equations in predicting the mortality of patients after OPCABG. Postoperative renal function was more efficiently predicted compared with the preoperative one.

Abdominal obesity phenotypes and risk of kidney function decline: Tehran Lipid and Glucose Study

OBJECTIVE

Obesity and related health risk in different obesity phenotypes has always been a controversial subject. The present study was conducted with the aim of investigating the risk of kidney function decline (KFD) incidence in different abdominal obesity phenotypes.

METHODS

In this prospective observational cohort study, 7002 individuals (56.1% female), aged ≥20 years, were followed for the incidence of KFD defined as 40% decline in eGFR. Abdominal obesity was defined based on waist circumference cut-offs ≥89/91cm for men/women, respectively. Metabolic health was defined as ≤1 criterion of the metabolic syndrome criteria, according to the Joint Interim Statement (JIS) definition.

RESULTS

At baseline 4273 individuals (61.0%) were abdominally obese, among whom, 1188 (27.8%) belonged to the metabolically healthy abdominal obese (MHAO) phenotype. Totally, 251 incidences of KFD was indicated throughout the 12-year follow-up. After adjusting for the confounding variables, MHAO phenotype was not associated with increased risk of KFD in both males and females. Furthermore, results indicated that hazard ratios (HRs) for incidence of KFD did not increase in males with unhealthy obesity phenotypes. However, females with metabolically unhealthy abdominal obese (MUAO) phenotype had increased risk of KFD.

CONCLUSION

Findings of this study indicated that MHAO phenotype was not associated with KFD incidence, regardless of the participants gender. Furthermore, MUAO phenotype was associated with higher risk of KFD only in females. Further studies with longer follow up and larger sample size are needed to shed more light upon the regarded relationship and the influential role of gender.

How to estimate glomerular filtration rate in sub-Saharan Africa: design and methods of the African Research into Kidney Diseases (ARK) study

BACKGROUND

Chronic kidney disease (CKD) is a substantial cause of morbidity and mortality worldwide with disproportionate effects in sub-Saharan Africa (SSA). The optimal methods to estimate glomerular filtration rate (GFR) and therefore to determine the presence of CKD in SSA are uncertain. We plan to measure iohexol excretion to accurately determine GFR in Malawi, South Africa and Uganda. We will then assess the performance of existing equations to estimate GFR and determine whether a modified equation can better improve estimation of GFR in sub-Saharan Africa.

METHODS

The African Research on Kidney Disease (ARK) study is a three-country study embedded within existing cohorts. We seek to enrol 3000 adults > 18 years based on baseline serum creatinine. Study procedures include questionnaires on socio-demographics and established risk factors for kidney disease along with anthropometry, body composition, blood pressure, blood chemistry and urine microscopy and albuminuria. We will measure GFR (mGFR) by plasma clearance of iohexol at 120, 180 and 240 min. We will compare eGFR determined by established equations with mGFR using Bland-Altman plots. We will use regression methods to estimate GFR and compare the newly derived model with existing equations.

DISCUSSION

Through the ARK study, we aim to establish the optimal approach to estimate GFR in SSA. The study has the advantage of drawing participants from three countries, which will increase the applicability of the findings across the region. It is also embedded within established cohorts that have longitudinal information and serial measures that can be used to characterize kidney disease over a period of time. This will help to overcome the limitations of previous research, including small numbers, selected population sub-groups, and lack of data on proteinuria. The ARK collaboration provides an opportunity for close working partnerships across different centres, using standardized protocols and measurements, and shared bio-repositories. We plan to build on the collaboration for this study for future work on kidney disease in sub-Saharan Africa, and welcome additional partners from across the continent.

Comparison of five glomerular filtration rate estimating equations as predictors of acute kidney injury after cardiovascular surgery

We aimed to compare the ability of preoperative estimated glomerular filtration rate (eGFR), calculated using five different equations, to predict adverse renal outcomes after cardiovascular surgery. Cohorts of 4,125 adult patients undergoing elective cardiovascular surgery were evaluated. Preoperative eGFR was calculated using the Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) II, re-expressed MDRD II, Chronic Kidney Disease Epidemiology Collaboration, and Mayo quadratic (Mayo) equations. The primary outcome was postoperative acute kidney injury (AKI), defined by Kidney Disease: Improving Global Outcomes Definition and Staging criteria based on changes in serum creatinine concentrations within 7 days. The MDRD II and Cockcroft-Gault equations yielded the highest (88.1 ± 26.7 ml/min/1.73 m2) and lowest (79.6 ± 25.5 ml/min/1.73 m2) mean eGFR values, respectively. Multivariable analysis showed that a preoperative decrease in renal function according to all five equations was independently associated with an increased risk of postoperative AKI. The area under the receiver operating characteristics curve for predicting postoperative AKI was highest for the Mayo equation (0.713). Net improvements in reclassification and integrated discrimination were higher for the Mayo equation than for the other equations. The Mayo equation was the most accurate in predicting postoperative AKI in patients undergoing cardiovascular surgery.

Type 2 diabetes treatment and progression of chronic kidney disease in Italian family practice

AIMS

Progressive chronic kidney disease represents a dreadful complication of type 2 diabetes mellitus (T2DM). We tested the pattern of use and the renal effects of old glucose-lowering drugs in T2DM patients cared for by Italian general practitioners (GPs).

METHODS

Data of 2606 T2DM patients were extracted from the databases of GPs, who do not have access to the most recent glucose-lowering drugs in Italy. The rate of kidney function decline was calculated by CKD-EPI_cr, based on two consecutive creatinine values.

RESULTS

Metformin was used in 55% of cases, either alone or with sulfonylureas/repaglinide, across the whole spectrum of CKD (from 66% in stage G1 to only 8% in G4). Sulfonylurea use peaked at 21-22% in stage G2-G3a, whereas repaglinide use significantly increased from 8% in G1 to 22% in G4. The median rate of CKD decline was - 1.64 mL/min/1.73 m² per year; it was higher in G1 (- 3.22 per year) and progressively lower with CKD severity. 826 cases (31.7%) were classified as fast progressors (eGFR decline more negative than - 5 mL/min/1.73 m² per year). The risk of fast progressing CKD was associated with increasing BMI, albuminuria, and sulfonylurea use, alone (OR, 1.47; 95% confidence interval, 1.16-1.85), or in association with metformin (OR, 1.40; 95% CI 1.04-1.88). No associations were demonstrated for metformin, cardiovascular and lipid lowering drug use.

CONCLUSION

In the setting of Italian family practice, sulfonylurea use is associated with progressive CKD in patients with T2DM. Metformin, at doses progressively reduced according to CKD stages, as recommended by guidelines, is not associated with fast progression.

The Association between Obesity Phenotypes and Early Renal Function Decline in Adults without Hypertension, Dyslipidemia, and Diabetes

Background

The prevalence of chronic kidney disease is increasing worldwide. Several studies have suggested that obesity is associated with early renal dysfunction. However, little is known about the relationship between obesity phenotypes and early renal function decline. Therefore, this study aimed to identify the relationship between obesity phenotypes and early renal function decline in adults without hypertension, dyslipidemia, and diabetes.

Methods

We conducted a cross-sectional analysis of clinical and anthropometric data from 1,219 patients who underwent a routine health checkup in 2014. We excluded adults with cardiovascular disease, renal disease, diabetes, hypertension, dyslipidemia, or low glomerular filtration rate (<60 mL/min/1.73 m²). Renal function was determined according to the estimated glomerular filtration rate calculated using the Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin C equation.

Results

Age, sex, body mass index, waist circumference, triglyceride, low-density lipoprotein, and fasting glucose had an association with the estimated glomerular filtration rate. After adjusting for age, sex, smoking status, and alcohol intake, the odds ratios of the metabolically abnormal normal weight and metabolically abnormal obese phenotypes for the presence of low estimated glomerular filtration rates were 1.807 (95% confidence interval, 1.009– 3.236) and 1.834 (95% confidence interval, 1.162–2.895), compared with the metabolically healthy normal weight phenotype. However, the metabolically healthy obese phenotype did not show a significant association with early renal function decline.

Conclusion

In this cross-sectional study, we confirmed the association between the metabolically abnormal normal weight and metabolically abnormal obese phenotypes and early kidney function decline in adults without hypertension, dyslipidemia, and diabetes.

Analysis of the risk factors for contrast-induced nephropathy in over-aged patients receiving coronary intervention

Contrast-induced nephropathy has been the common cause of hospital-acquired acute kidney injury in the elderly patients. This study aimed to analyze the risk factors for contrast-induced nephropathy in over-aged patients undergoing coronary angiography or percutaneous coronary intervention. A total of 470 over-aged patients (≥80 years old) were judged as the contrast-induced nephropathy group ( n = 46) and non-contrast-induced nephropathy group ( n = 424) according to the postoperative 48-h serum creatinine levels. The patients' clinical information such as hypertension grade, number and degree of coronary artery stenosis, and death rate was compared. The risk factors for contrast-induced nephropathy were also analyzed. The hypertension grade in the contrast-induced nephropathy group was significantly higher than that in the non-contrast-induced nephropathy group ( P = 0.004). The degree of coronary artery stenosis was significantly more in the contrast-induced nephropathy group compared with the non-contrast-induced nephropathy group ( P = 0.003). The death rate of the contrast-induced nephropathy group (15.8%) was significantly higher than that of the non-contrast-induced nephropathy group (0.6%; P = 0.000). The percentage of patients with abnormal urine microalbumin was significantly bigger in the contrast-induced nephropathy group (62.5%) when comparing to the non-contrast-induced nephropathy group (23.6%; P = 0.00). Besides, there was also significant difference in the emergency/selective operation between the contrast-induced nephropathy group and non-contrast-induced nephropathy group ( P = 0.001). Further, hypertension grade ( P = 0.019), emergency/selective operation ( P = 0.025), degree of coronary artery stenosis ( P = 0.038), eGFR ( P = 0.034), and urine microalbumin ( P = 0.005) were the risk factors for contrast-induced nephropathy. Hypertension grade, emergency/selective operation, degree of coronary artery stenosis, eGFR, and urine microalbumin were the risk factors for contrast-induced nephropathy in over-aged patients receiving coronary angiography and percutaneous coronary intervention, providing guidance for the clinical prevention of contrast-induced nephropathy. Impact statement In this work, we evaluated the risk factors for contrast-induced nephropathy (CIN) in over-aged patients receiving coronary angiography (CAG) and percutaneous coronary intervention (PCI). We found that hypertension grade, emergency/selective operation, degree of coronary artery stenosis, eGFR, and urine microalbumin were the risk factors for CIN in over-aged patients receiving CAG and PCI. This study provides guidance for the clinical prevention of CIN in over-aged patients undergoing coronary intervention, highlighting that a perioperative comprehensive management strategy is needed to improve the prognosis.

Incidence and risk factors for tenofovir-associated nephrotoxicity among human immunodeficiency virus-infected patients in Korea

BACKGROUND/AIMS

Little is known about tenofovir disoproxil fumarate (TDF)-induced nephrotoxicity in human immunodeficiency virus (HIV)-infected patients in Korea. The objective of this study was to evaluate the incidence and risk factors of TDF-associated nephrotoxicity among HIV-infected patients in Korea.

METHODS

A single-center retrospective cohort study was conducted on HIVinfected patients in Korea. We included patients who had started TDF or abacavir (ABC)-based antiretroviral therapy (ART) between October 2006 and December 2014. Estimated glomerular filtration rate (eGFR) was estimated using the Chronic Kidney Disease-Epidemiology Collaboration equation. Renal dysfunction was defined as > 25% decrease of baseline eGFR. A propensity matched case-control study was conducted to compare renal dysfunction rates between the two groups. The risk factors of nephrotoxicity were analyzed by Cox regression analysis.

RESULTS

A total of 210 HIV-infected patients were included in the study, of which, 108 were TDF-based ART group and 102 were ABC-based ART group. Renal dysfunction occurred in 16 patients (14.8%) in the TDF group and 11 (10.8%) in the ABC group. Incidence of renal dysfunction of TDF and ABC group was 9.66 per 100 person-years (PYs) and 5.14 per 100 PYs, respectively (p = 0.176). In propensityscore-matched analysis, renal dysfunction rates were TDF 13.3% versus ABC 13.3% (p > 0.999). In multivariable analysis, Centers for Disease Control and Prevention clinical category C was a significant risk factor for renal dysfunction.

CONCLUSION

Approximately, 13% of HIV-infected patients treated with TDF had renal dysfunction. Advanced stage of HIV infection was a significant risk factor for renal dysfunction.

Accuracy Assessment of Five Equations Used for Estimating the Glomerular Filtration Rate in Korean Adults

BACKGROUND

We aimed to assess the performance of the five creatinine-based equations commonly used for estimates of the glomerular filtration rate (eGFR), namely, the creatinine-based Chronic Kidney Disease Epidemiology Collaboration (CKD-EPIcr), Asian CKD-EPI, revised Lund-Malmö (revised LM), full age spectrum (FAS), and Korean FAS equations, in the Korean population.

METHODS

A total of 1,312 patients, aged 20 yr and above who underwent ⁵¹Cr-EDTA GFR measurements (mGFR), were enrolled. The bias (eGFR-mGFR) and precision (root mean square error [RMSE]) were calculated. The accuracy (P30) of four eGFR equations was compared to that of the CKD-EPIcr equation. P30 was defined as the percentage of patients whose eGFR was within±30% of the mGFR.

RESULTS

The mean bias (mL·min⁻¹·1.73 m⁻²) of the five eGFR equation was as follows: CKD-EPIcr, -0.6; Asian CKD-EPI, 2.7; revised LM, -6.5; FAS, -2.5; and Korean FAS, -0.2. The bias of the Asian CKD-EPI, revised LM, and FAS equations showed a significant difference from zero (P<0.001). The RMSE values were as follows: CKD-EPIcr, 15.6; Asian CKD-EPI, 15.6; revised LM, 17.9; FAS, 16.3; and Korean FAS, 15.8. There were no significant differences in the P30 except for the Asian CKD-EPI equation: CKD-EPIcr, 76.6%; Asian CKD-EPI, 74.7%; revised LM, 75.8%; FAS, 76.0%; and Korean FAS, 75.8%.

CONCLUSIONS

The CKD-EPIcr and Korean FAS equations showed equivalent analytical and clinical performances in the Korean adult population.