Removing race from the CKD-EPI equation and its impact on prognosis in a predominantly White European population

Quantitative Assessment of the Effect of Chronic Kidney Disease on Plasma P-Tau217 Concentrations

BACKGROUND AND OBJECTIVES

Chronic kidney disease (CKD) is known to be associated with increased plasma phosphorylated tau217 (p-tau217) concentrations, potentially confounding the utility of plasma p-tau217 measurements as a marker of amyloid pathology in individuals with suspected Alzheimer disease (AD). In this study, we quantitatively investigate the relationship of plasma p-tau217 concentrations vs estimated glomerular filtration rate (eGFR) in individuals with CKD with and without amyloid pathology.

METHODS

This was a retrospective examination of data from 2 observational cohorts from either the Mayo Clinic Study of Aging or the Alzheimer's Disease Research Center cohorts. p-Tau217 was determined using the ALZpath Simoa p-tau217 immunoassay and an immunoprecipitation mass spectrometry assay that simultaneously measures p-tau217 and nonphosphorylated-tau217 (np-tau217) to determine %p-tau217 ([p-tau217/nonphosphorylated-tau217]) × 100%) (C2N Diagnostics). Amyloid positivity was defined by amyloid-PET and a centiloid of ≥25. Log-log linear regression fits were used to quantitatively predict increases in plasma p-tau217 associated with decreasing eGFR.

RESULTS

Participants (n = 202, mean age of 78 years, 38% female) with diagnoses of cognitive unimpairment (n = 109), mild cognitive impairment (n = 71), and dementia (n = 22) were included. In all, 114 (56%) of all participants were amyloid-PET positive (A+). In addition, 86 (43%) of all participants were classified as having CKD (CKD stages 3-4). p-Tau217 concentrations were significantly higher in A- participants with an eGFR of <60 (mL/min/1.73 m2), as compared with those with eGFR >60 A- participants. For an eGFR of 45 vs 60 in the A- cohort, the calculated percentage changes were +31%, +55%, and +19%, for ALZpath p-tau217, C2N p-tau217, and C2N %p-tau217, respectively. For the A+ cohort, the corresponding calculated percentage changes were +17%, +15%, and -5%, respectively.

DISCUSSION

CKD was associated with increased p-tau217 concentrations when measuring p-tau217 by ALZpath and C2N methodologies, but the effect was mitigated by the use of %p-tau217. These results indicate limitations for the utility of plasma p-tau217 measurements in individuals with significant renal impairment (eGFR <45 or CKD stage 3b or greater). Determination of eGFR should be considered to avoid inaccurate classification of the presence of AD-related pathology by plasma p-tau217 in individuals with CKD.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that in individuals with CKD stage 3 (especially stage 3b) or higher, p-tau217 concentrations are increased, with a greater increase in amyloid-PET-negative individuals.

Classification of chronic kidney disease in older Australian adults by the CKD-EPI 2009 and 2021 equations: secondary analysis of ASPREE study data

OBJECTIVES

To assess the clinical impact on generally healthy older Australians of changing from the 2009 CKD-EPI (CKD-EPI2009) to the 2021 CKD-EPI (CKD-EPI2021) equation for calculating the estimated glomerular filtration rate (eGFR).

STUDY DESIGN

Secondary analysis of data from the prospective ASPirin in Reducing events in the Elderly (ASPREE) cohort study.

SETTING, PARTICIPANTS

Australians aged 70 years or older living in the community and without life-limiting medical conditions, recruited 1 March 2010 - 31 December 2014 for the ASPREE trial.

MAIN OUTCOME MEASURES

Baseline characteristics and long term health outcomes for participants classified to different chronic kidney disease (CKD) stages by CKD-EPI2021 and CKD-EPI2009, and for those classified to the same CKD stage by both equations.

RESULTS

Complete data were available for 16 244 Australian ASPREE trial participants. At baseline, their mean age was 75.3 years (standard deviation, 4.4 years), and 8938 were women (55%); the median eGFR (CKD-EPI2009) was 74 mL/min/1.73 m2 (interquartile range [IQR], 64-85 mL/min/1.73 m2), the median urine albumin-to-creatinine ratio 0.8 mg/mmol (IQR, 0.5-1.4 mg/mmol). eGFR values were higher for most participants with CKD-EPI2021 than with CKD-EPI2009 (median difference, 3.8 mL/min/1.73 m2; IQR, 3.3-4.4 mL/min/1.73 m2), and 3274 participants (20%) were classified to less advanced CKD stages by CKD-EPI2021. The proportion of participants with eGFR values below 60 mL/min/1.73 m2 (clinical CKD) was 17% (2770 participants) with CKD-EPI2009 and 12% (1994 participants) with CKD-EPI2021. Participants were followed up at a median of 6.5 years (IQR, 5.4-7.9 years); the risks of reaching the disability-free survival composite endpoint (adjusted hazard ratio [aHR], 0.94; 95% confidence interval [CI], 0.84-1.05), all-cause mortality (aHR, 0.90; 95% CI, 0.78-1.03), major cardiac events (aHR, 0.94; 95% CI, 0.79-1.13), and hospitalisations with heart failure (aHR, 1.00; 95% CI, 0.67-1.49) were each similar for participants reclassified or not reclassified by CKD-EPI2021.

CONCLUSIONS

Using CKD-EPI2021 would yield higher eGFR values than the CKD-EPI2009, substantially reducing the proportion of older Australian adults classified as having CKD, without any overall difference in long term health outcomes for people reclassified to less advanced CKD stages. Using the CKD-EPI2021 could markedly reduce the number of referrals of generally healthy older adults to specialist nephrology services.

Unveiling the interaction and combined effects of multiple metals/metalloids exposure to TNF-α and kidney function in adults using bayesian kernel machine regression and quantile-based G-computation

BACKGROUND

Exposure to multiple metals may cause adverse effects, particularly in the kidneys. However, studies on the combined and interaction effects of metal mixtures on human health remain limited.

OBJECTIVE

The study aims to evaluate the interaction between metals and assess the combined effects of exposure to metal mixtures on tumor necrosis factor-alpha (TNF-α) levels and kidney function METHODS: Particular emphasis has been placed on the impact of various metals, including arsenic (As), cadmium (Cd), lead (Pb), as well as essential trace elements, such as cobalt (Co), copper (Cu), selenium (Se), and zinc (Zn), on human health and their potential collective influence on both TNF-α and kidney function. This cross-sectional study analyzed the data of 421 adults who underwent a health examination. Generalized linear model (GLM), Bayesian kernel machine regression (BKMR), and quantile-based G-computation (qgcomp) were used to evaluate the association and joint effects between the metals and TNF-α, as well as kidney function.

RESULTS

Increased concentrations of As (β = 0.11, 95 % CI = 0.05, 0.17) and Pb (β = 0.30, 95 % CI = 0.23, 0.37) in the blood were associated with elevated levels of TNF-α, while elevated Cu (β = -0.42, 95 % CI = -0.77, -0.07) levels were linked to a significant reduction in TNF-α. The overall effect of metals mixture showed a significant association with a decline in eGFR and an increase TNF-α in the BKMR model. Qgcomp analysis of the metals mixture (β = -0.06, 95 % CI = -0.07, -0.05) indicated that As, Pb, and Zn were the primary contributors to the reduction in eGFR, while As and Pb were the major contributors in metals mixture (β = 0.12, 95 % CI = 0.08, 0.15) to the elevation of TNF-α levels.

CONCLUSION

Exposure to multiple metals could have joint association with the TNF-α levels and kidney function. Furthermore, TNF-α could act as a mediator between metal mixtures and eGFR.

What every clinician needs to know about chronic kidney disease: Detection, classification and epidemiology

Chronic kidney disease (CKD) is a major healthcare challenge, affecting >800 million people worldwide. Implications for population health result from the strong associations of CKD with increased rates of cardiovascular disease, heart failure, progressive CKD leading to kidney failure, acute kidney injury (AKI), and mortality. In addition to a single disease perspective, CKD commonly coexists alongside other long-term conditions, in particular type 2 diabetes and cardiovascular disease. CKD is therefore an important component of multimorbidity that influences individual management and impacts prognosis. CKD is defined by abnormalities of kidney structure or function of any cause with implications for health that are present for longer than 3 months. The diagnosis is usually made on the basis of an abnormal glomerular filtration rate (GFR < 60 mL/min/1.73 m2) and/or the presence of proteinuria (urine albumin to creatinine ratio > 30 mg/g or >3 mg/mmol). GFR is usually estimated from serum creatinine concentration using a variety of validated equations. However, serum creatinine is closely related to muscle mass and may therefore not be an accurate marker of GFR in people with high or low muscle mass (sarcopaenia). Cystatin C is an alternative endogenous marker of GFR that is increasingly being used but also has limitations. An estimate of GFR based on both creatinine and cystatin C is the most accurate. Diagnosis should be followed by classification and risk stratification to guide the development of a risk-based, personalized care plan. Improved detection and widespread implementation of optimal CKD management has the potential to bring major benefits to population health.

How histopathological diagnosis interacts with kidney ultrasound parameters and glomerular filtration rate

The evaluation of estimated GFR (eGFR) is a pivotal staging step in patients with chronic kidney disease (CKD), and renal ultrasound plays an important role in diagnosis, prognosis and progression of CKD. The interaction between histopathological diagnosis and ultrasound parameters in eGFR determination has not been fully investigated yet. The study examined the results of native kidney biopsies performed in 48 Italian centers between 2012 and 2020. The primary goal was if and how the histopathological diagnosis influences the relationship between ultrasound parameters and eGFR. After exclusion of children, patients with acute kidney injury and patients without measure of kidney length or parenchymal thickness, 2795 patients have been selected for analysis. The median values were 52 years for patient age, 11 cm for bipolar kidney diameter, 16 mm for parenchymal thickness, 2.5 g/day for proteinuria and 70 ml/min/1.73 m2 for eGFR. The bipolar kidney diameter and the parenchymal thickness were directly related with eGFR values (R square 0.064). Diabetes and proteinuria were associated with a consistent reduction of eGFR, improving the adjusted R square up to 0.100. Addition of histopathological diagnosis in the model increased the adjusted R square to 0.216. There is a significant interaction between histopathological diagnosis and longitudinal kidney diameter (P 0.006). Renal bipolar length and parenchymal thickness are directly related with eGFR. The magnitude of proteinuria and histopathological kidney diagnosis are associated with eGFR. The relationship between kidney length and the level of eGFR depends on the nature of the kidney disease.

Prediction of cardiovascular events and all-cause mortality using race and race-free estimated glomerular filtration rate in African Americans: the Jackson Heart Study

Background

New Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations without a race adjustment were developed to estimate the glomerular filtration rate (eGFR). We aimed to compare the performance of five CKD-EPI eGFR equations, with or without race, in predicting cardiovascular disease (CVD) events and all-cause mortality in Black Americans from the Jackson Heart Study.

Methods

JHS is an ongoing population-based prospective cohort study of African Americans in the Jackson, Mississippi, metropolitan area. Five CKD-EPI equations were used to estimate GFR at baseline using serum creatinine (Cr) or cystatin C (cys), including 2009 eGFRcr(ASR [age, sex, race]), 2021 eGFRcr(AS [age and sex]), 2012 eGFRcr-cys(ASR), 2021 eGFRcr-cys(AS), 2012 eGFRcys(AS). Endpoints were incident CVD events and all-cause mortality. Cox proportional hazards regression was used to assess the associations between different eGFRs and outcomes adjusting for atherosclerotic risk factors. Harrell's C-statistics and Net Reclassification Index (NRI) were used to assess the predictive utility.

Results

Among 5,129 participants (average age 54.8 ± 12.8 yrs), 1898 were male (37.0%). eGFRcr(AS) provided lower estimates and resulting in a greater proportion of participants categorized as CKD than eGFRcr(ASR), eGFRcr-cys(ASR), eGFRcr-cys(AS) and eGFRcys(AS). A median follow-up of 13.7 and 14.3 years revealed 411 (9.3%) CVD incidents and 1,207 (23.5%) deaths. Lower eGFRs were associated with CVD incidents and all-cause mortality. eGFRcr-cys(ASR), eGFRcr-cys(AS) and eGFRcys(AS) were strongly associated with incident CVD events and all-cause mortality than eGFRcr(ASR) and eGFRcr(AS). A significant discrimination improvement was found in C-statistics for predicting incident CVD events and all-cause mortality after adding each eGFR measure to the basic model including atherosclerotic risk factors. Across a 7.5% 10-year risk threshold, eGFRcys(AS) improved net classification of all-cause mortality (NRI: 2.19, 95%CI: 0.08, 4.65%).

Conclusion

eGFR based on creatinine omit race has the lowest mean and detects more CKD patients in Black population. The eGFRs incorporating cystatin C strengthens the association between the eGFR and the risks of incident CVD and all-cause mortality. Cystatin C-based eGFR equations might be more appropriate for predicting CVD and mortality among Black population.

Prognostic impact of switching to the 2021 chronic kidney disease epidemiology collaboration creatinine-based equation in Caucasian patients with type 2 diabetes: the Renal Insufficiency and Cardiovascular events (RIACE) Italian Multicenter Study

BACKGROUND

A Chronic Kidney Disease (CKD) Epidemiology Collaboration (EPI) formula not including a Black race coefficient has been recently developed and is now recommended in the US. The new (2021) equation was shown to yield higher estimated glomerular filtration rate (eGFR) values than the old (2009) one in a non-Black general population sample, thus reclassifying a significant number of individuals to a better eGFR category. However, reclassified individuals were previously shown to have a lower risk of progression to end-stage kidney disease, but higher adjusted risks for all-cause death and morbidity and mortality from cardiovascular disease than those not reclassified. This study evaluated the prognostic impact of switching from the 2009 to the 2021 CKD-EPI equation in non-Black individuals with type 2 diabetes.

METHODS

The Renal Insufficiency And Cardiovascular Events (RIACE) was a prospective cohort study enrolling 15,773 Caucasian patients in 19 Italian centers in 2006-2008. Cardiometabolic risk profile, treatments, complications, and comorbidities were assessed at baseline and eGFR was calculated with the two equations. Vital status was retrieved on 31 October 2015 for 15,656 participants (99.3%).

RESULTS

With the 2021 equation, the eGFR value increased in all patients, except for 293 individuals with a 2009 eGFR ≥ 105 ml·min- 1·1.73 m- 2. The median difference was 4.10 ml·min- 1·1.73 m- 2 and was higher in males, older individuals and those in the G2 category. Reclassification decreased the percentage of patients with reduced eGFR from 17.28 to 13.96% and with any CKD from 36.23 to 34.03%. Reclassified individuals had better cardiometabolic risk profile and lower prevalence of complications and use of medications than non-reclassified individuals. Risk of death versus the 2009 G1 category was lower for reclassified than non-reclassified participants in all eGFR categories and, particularly, in each 2009 eGFR category, though difference was significant only in the G4-G5 category. The Receiver Operator Characteristic curves were statistically, but not clinically different with the two equations.

CONCLUSION

Changing from the 2009 to the 2021 CKD-EPI equation results in higher eGFR and lower CKD prevalence, with a lower risk of death in reclassified patients with an eGFR < 30 ml·min- 1·1.73 m- 2, but virtually no impact on mortality prediction.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00715481, retrospectively registered 15 July, 2008.

Reliability of GFR Estimated by Creatinine-Based Formulas in Moderate-to-Severe Proteinuria

Background:

Creatinine-based Glomerular Filtration rate (GFR) formulas introduce a substantial bias in GFR estimations in patients with frank nephrotic syndrome. The bias and accuracy of creatinine-based GFR estimates (eGFR) in patients with non-nephrotic proteinuria need better characterization.

Methods:

We utilized data from the Ramipril in non-diabetic renal failure (REIN 1) and REIN 2 trials involving non-diabetic chronic kidney disease (CKD) patients with proteinuria to compare eGFRs derived from the CKD Epidemiology Consortium (CKD-EPI)formulas (with and without race), and the European Kidney Function Consortium (EKFC) equations with iohexol clearance (a gold-standard GFR measure, measured glomerular filtration rate [mGFR]). Bias was defined as the median difference between eGFR and mGFR, while accuracy was assessed using P30 and P15 metrics, which represent the percentage of eGFR values within ±30% and ±15% of mGFR, respectively.

Results:

The median bias of the three formulas being compared did not differ, being minimal and in a strict range (0.04 to 0.05 ml/ml/min/1.73m2) in the REIN 1 study and (-0.04 to -0.03 ml/min/1.73 m2) in the REIN 2 study. These findings were confirmed in analyses stratified by age and mGFR. The global accuracy of the three formulas regarding P30% showed sufficient accuracy (P30 >75%) in REIN 1 and all strata in REIN 2, but the mGFR stratum <15 ml/min/1.73m2.

Conclusion:

The CKD-EPI (with and without race), and EKFC equations show no significant bias and sufficient accuracy in patients with proteinuria. These formulas can be safely applied to non-diabetic CKD patients with moderate to severe proteinuria.

Creatinine clearance/eGFR ratio: a simple index for muscle mass related to mortality in ICU patients

INTRODUCTION

In patients admitted to the intensive care unit (ICU), muscle mass is inversely associated with mortality. Although muscle mass can be estimated with 24-h urinary creatinine excretion (UCE), its use for risk prediction in individual patients is limited because age-, sex-, weight- and length-specific reference values for UCE are lacking. The ratio between measured creatinine clearance (mCC) and estimated glomerular filtration rate (eGFR) might circumvent this constraint. The main goal was to assess the association of the mCC/eGFR ratio in ICU patients with all-cause hospital and long-term mortality.

METHODS

The mCC/eGFR ratio was determined in patients admitted to our ICU between 2005 and 2021 with KDIGO acute kidney injury (AKI) stage 0-2 and an ICU stay ≥ 24 h. mCC was calculated from UCE and plasma creatinine and indexed to 1.73 m2. mCC/eGFR was analyzed by categorizing patients in mCC/eGFR quartiles and as continuous variable.

RESULTS

Seven thousand five hundred nine patients (mean age 61 ± 15 years; 38% female) were included. In-hospital mortality was 27% in the lowest mCC/eGFR quartile compared to 11% in the highest quartile (P < 0.001). Five-year post-hospital discharge actuarial mortality was 37% in the lowest mCC/eGFR quartile compared to 19% in the highest quartile (P < 0.001). mCC/eGFR ratio as continuous variable was independently associated with in-hospital mortality in multivariable logistic regression (odds ratio: 0.578 (95% CI: 0.465-0.719); P < 0.001). mCC/eGFR ratio as continuous variable was also significantly associated with 5-year post-hospital discharge mortality in Cox regression (hazard ratio: 0.27 (95% CI: 0.22-0.32); P < 0.001).

CONCLUSIONS

The mCC/eGFR ratio is associated with both in-hospital and long-term mortality and may be an easily available index of muscle mass in ICU patients.

Estimated GFR in the Korean and US Asian Populations Using the 2021 Creatinine-Based GFR Estimating Equation Without Race

Rationale & Objective

In 2021, the new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) updated the creatinine-based estimated glomerular filtration rate (eGFR) equation and removed the coefficient for race. The development and validation of this equation involved binarizing race into African American and non-African American, involving few Asian participants. This study aimed to examine the difference between the 2021 equation and the previous 2009 equation on CKD prevalence estimates in 2 Asian populations.

Study Design

Observational study using 2 national surveys.

Setting & Participants

Participants from the 2019 Korea National Health and Nutrition Survey and participants self-reported as Asian from the 2011-2020 US National Health and Nutrition Survey.

Exposure

eGFR using 2009 and 2021 CKD-EPI creatinine equation.

Outcomes

Prevalence of CKD (eGFR <60 mL/min/1.73 m2 or urine albumin-creatinine ratio ≥30 mg/g).

Analytical Approach

Sampling-weighted prevalence estimated using the 2009 and 2021 equations as well as the percentage of individuals with CKD G3+ using the 2009 equation being reclassified as not having CKD G3+ using the 2021 equation.

Results

The prevalence of CKD estimated using the 2021 equation was 9.75% (95% confidence intervals [CI], 8.80-10.80%) in Koreans and 11.60% (95% CI, 10.23-13.13%) in US Asians. The prevalence of CKD estimated using the 2021 equation was slightly lower than that using the 2009 equation in both Korean and US Asian populations by 0.63% (95% CI, 0.44-0.90%) and 0.84% (95% CI, 0.52-1.34%), respectively. Furthermore, 32.8% and 30.2% of Koreans and US Asians with CKD G3-5, respectively, estimated using the 2009 equation were reclassified as not having CKD G3-5 when the eGFR was calculated using the 2021 equation.

Limitations

Measured GFR was not available.

Conclusions

Use of the 2021 CKD-EPI creatinine equation leads to a small decrease in CKD prevalence in both Korean and US Asian populations, and of similar magnitude, resulting in significant reclassification among those originally classified as having CKD G3+.

Kidney function assessment for eligibility in clinical cancer trials - Data from the European Organisation for Research and Treatment of Cancer

PURPOSE

There is no consensus on how to estimate kidney function for the assessment of eligibility in clinical cancer trials.

PATIENTS AND METHODS

We recalculated the creatinine clearance (CrCl)/glomerular filtration rate (GFR) at baseline in a total of 1768 patients enrolled in twelve clinical trials using the Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI 2021) and European Kidney Function Consortium (EKFC) formulas. Patients were classified as having renal impairment (RI; CrCl/GFR <60 mL/min) or no renal impairment (NRI; CrCl/GFR ≥60 mL/min) with each of the four formulas, respectively. Furthermore, we analyzed the number of adverse events (AE) per month under study treatment using measures of central tendency, variability and regression models.

RESULTS

Using CG, EKFC, MDRD and CKD-EPI 2021, 152 (8 %), 140 (8 %), 110 (6 %), and 61 (4 %) patients had RI respectively. Indeed, 47 (3 %) patients had RI using all 4 formulas, while 158 (9 %) had RI by at least one but not all four methods. CG showed the broadest variability and inconsistencies with other methods. All calculation methods performed similarly for excluding patients at risk of severe AE. EKFC demonstrated superior predictive ability for excluding patients at risk of renal and urinary tract AE.

CONCLUSION

This post hoc analysis highlights the importance of choosing accurate and representative methods for kidney function estimation in clinical cancer trials. CG should be replaced by newer methods. While CKD-EPI 2021 may maximize trial accrual, EKFC should be considered for treatment affecting kidney function.

A commentary from the European Renal Best Practice (ERBP) on the Kidney Disease Improving Global Outcomes (KDIGO) 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease in children and adults

The Kidney Disease: Improving Global Outcomes (KDIGO) 2024 Guidelines for identification and management of chronic kidney disease (CKD) are a welcome development coming 12 years after the paradigm changing 2012 guidelines. We are living in an unprecedented era in nephrology with novel therapies, including sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists and non-steroidal mineralocorticoid receptor antagonists now being proven in multiple randomised controlled clinical trials to reduce both the progression of CKD and cardiovascular morbidity and mortality. The KDIGO 2024 CKD guideline is aimed at a broad audience looking after children and adults with CKD and provide practical and actionable steps to improve care. This commentary reviews the guideline sections pertaining to the evaluation and risk assessment of individuals with CKD from a European perspective. We feel that despite the last guideline being published 12 years ago, and that the assessment of CKD has been emphasized by many other national/international nephrology, cardiology and diabetology guidelines and societies, the diagnosis and treatment of CKD remains poor across Europe. As such the KDIGO 2024 CKD Guidelines should be seen as an urgent call to action to improve diagnosis and care of children and adults with CKD across Europe. We know what we need to do. We now need to get on and do it.

Chronic kidney disease: detect, diagnose, disclose-a UK primary care perspective of barriers and enablers to effective kidney care

Chronic kidney disease (CKD) is a global public health problem with major human and economic consequences. Despite advances in clinical guidelines, classification systems and evidence-based treatments, CKD remains underdiagnosed and undertreated and is predicted to be the fifth leading cause of death globally by 2040. This review aims to identify barriers and enablers to the effective detection, diagnosis, disclosure and management of CKD since the introduction of the Kidney Disease Outcomes Quality Initiative (KDOQI) classification in 2002, advocating for a renewed approach in response to updated Kidney Disease: Improving Global Outcomes (KDIGO) 2024 clinical guidelines. The last two decades of improvements in CKD care in the UK are underpinned by international adoption of the KDIGO classification system, mixed adoption of evidence-based treatments and research informed clinical guidelines and policy. Interpretation of evidence within clinical and academic communities has stimulated significant debate of how best to implement such evidence which has frequently fuelled and frustratingly forestalled progress in CKD care. Key enablers of effective CKD care include clinical classification systems (KDIGO), evidence-based treatments, electronic health record tools, financially incentivised care, medical education and policy changes. Barriers to effective CKD care are extensive; key barriers include clinician concerns regarding overdiagnosis, a lack of financially incentivised care in primary care, complex clinical guidelines, managing CKD in the context of multimorbidity, bureaucratic burden in primary care, underutilisation of sodium-glucose co-transporter-2 inhibitor (SGLT2i) medications, insufficient medical education in CKD, and most recently - a sustained disruption to routine CKD care during and after the COVID-19 pandemic. Future CKD care in UK primary care must be informed by lessons of the last two decades. Making step change, over incremental improvements in CKD care at scale requires a renewed approach that addresses key barriers to detection, diagnosis, disclosure and management across traditional boundaries of healthcare, social care, and public health. Improved coding accuracy in primary care, increased use of SGLT2i medications, and risk-based care offer promising, cost-effective avenues to improve patient and population-level kidney health. Financial incentives generally improve achievement of care quality indicators - a review of financial and non-financial incentives in CKD care is urgently needed.

Laboratory-based surveillance of chronic kidney disease in people with private health coverage in Brazil

BACKGROUND

Although approximately 25% of Brazilians have private health coverage (PHC), studies on the surveillance of chronic kidney disease (CKD) in this population are scarce. The objective of this study was to estimate the prevalence of CKD in individuals under two PHC regimes in Brazil, who total 8,335,724 beneficiaries.

METHODS

Outpatient serum creatinine and proteinuria results of individuals from all five regions of Brazil, ≥ 18 years of age, and performed between 10/01/2021 and 10/31/2022, were analyzed through the own laboratory network database. People with serum creatinine measurements were evaluated for the prevalence and staging of CKD, and those with simultaneous measurements of serum creatinine and proteinuria were evaluated for the risk category of the disease. CKD was classified according to current guidelines and was defined as a glomerular filtration rate (GFR) < 60 ml/min/1.73 m² estimated by the 2021 CKD-EPI equation.

RESULTS

The number of adults with serum creatinine results was 1,508,766 (age 44.0 [IQR, 33.9-56.8] years, 62.3% female). The estimated prevalence of CKD was 3.8% (2.6%, 0.8%, 0.2% and 0.2% in CKD stages 3a, 3b, 4 and 5, respectively), and it was higher in males than females (4.0% vs. 3.7%, p < 0.001, respectively) and in older age groups (0.2% among 18-29-year-olds, 0.5% among 30-44-year-olds, 2.0% among 45-59-year-olds, 9.4% among 60-74-year-olds, and 32.4% among ≥ 75-year-olds, p < 0.001) Adults with simultaneous results of creatinine and proteinuria were 64,178 (age 57.0 [IQR, 44.8-67.3] years, 58.1% female). After adjusting for age and gender, 70.1% were in the low-risk category of CKD, 20.0% were in the moderate-risk category, 5.8% were in the high-risk category, and 4.1% were in the very high-risk category.

CONCLUSION

The estimated prevalence of CKD was 3.8%, and approximately 10% of the participants were in the categories of high or very high-risk of the disease. While almost 20% of beneficiaries with PHC had serum creatinine data, fewer than 1% underwent tests for proteinuria. This study was one of the largest ever conducted in Brazil and the first one to use the 2021 CKD-EPI equation to estimate the prevalence of CKD.

Implications of Implementing the 2021 CKD-EPI Equation Without Race on Managing Patients With Kidney Disease in British Columbia, Canada

Introduction

We investigated the implications of implementing race-free Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) 2021 equation among real-world patients with chronic kidney disease (CKD) from British Columbia (BC), Canada.

Methods

This study included nondialysis-dependent patients with CKD aged ≥19 years who were registered in the Patient Records and Outcome Management Information System (PROMIS) as of March 31, 2016 (index date) with ≥1 serum creatinine measurement within 1 year before the index date. Patients with a history of kidney transplantation before the index date were excluded. CKD-EPI 2021 versus 2009 equation was the exposure variable. Difference in mean estimated glomerular filtration rate (eGFR) and number (%) of patients reclassified to a different eGFR category were estimated. We used Fine and Gray subdistribution hazard model to investigate the association between change in eGFR category and progression to kidney failure (incident maintenance dialysis or kidney transplantation) within 2 years.

Results

A total of 11,604 patients (median age 73 years, 52% male) were included. Compared to the 2009 equation, eGFR from 2021 equation was on average 2.7 ml/min per 1.73 m2 higher. Variation was higher among males. Overall, ∼17% of the study sample were reclassified to a category with higher eGFR by 2021 equation (switchers). The highest proportion (28%) of patients were reclassified from G5 to G4. The risk of progressing to kidney failure was 22% less among switchers compared to nonswitchers; adjusted subdistribution hazard ratio (HR) (95% confidence interval [CI]) is 0.78 (0.65, 0.94).

Conclusion

CKD-EPI 2021 equation appeared to provide higher eGFR compared to 2009 equation. This higher eGFR values appeared to be concordant with subsequent real-world CKD progression outcomes. Higher eGFR from the 2021 equation may have substantial clinical implications in both diagnosis as well as long-term care of patients with CKD.

Evaluation of risk stratification for acute kidney injury: a comparative analysis of EKFC, 2009 and 2021 CKD-EPI glomerular filtration estimating equations

BACKGROUND

The adoption of the 2021 CKD-EPIcr equation for glomerular filtration rate (GFR) estimation provided a race-free eGFR calculation. However, the discriminative performance for AKI risk has been rarely validated. We aimed to evaluate the differences in acute kidney injury (AKI) prediction or reclassification power according to the three eGFR equations.

METHODS

We performed a retrospective observational study within a tertiary hospital from 2011 to 2021. Acute kidney injury was defined according to KDIGO serum creatinine criteria. Glomerular filtration rate estimates were calculated by three GFR estimating equations: 2009 and 2021 CKD-EPIcr, and EKFC. In three equations, AKI prediction performance was evaluated with area under receiver operator curves (AUROC) and reclassification power was evaluated with net reclassification improvement analysis.

RESULTS

A total of 187,139 individuals, including 27,447 (14.7%) AKI and 159,692 (85.3%) controls, were enrolled. In the multivariable regression prediction model, the 2009 CKD-EPIcr model (continuous eGFR model 2, 0.7583 [0.755-0.7617]) showed superior performance in AKI prediction to the 2021 CKD-EPIcr (0.7564 [0.7531-0.7597], < 0.001) or EKFC model in AUROC (0.7577 [0.7543-0.761], < 0.001). Moreover, in reclassification of AKI, the 2021 CKD-EPIcr and EKFC models showed a worse classification performance than the 2009 CKD-EPIcr model. (- 7.24 [- 8.21-- 6.21], - 2.38 [- 2.72-- 1.97]).

CONCLUSION

Regarding AKI risk stratification, the 2009 CKD-EPIcr equation showed better discriminative performance compared to the 2021 CKD-EPIcr equation in the study population.

Association of Low Glomerular Filtration Rate With Adverse Outcomes at Older Age in a Large Population With Routinely Measured Cystatin C

BACKGROUND

The commonly accepted threshold of glomerular filtration rate (GFR) to define chronic kidney disease (CKD) is less than 60 mL/min/1.73 m2. This threshold is based partly on associations between estimated GFR (eGFR) and the frequency of adverse outcomes. The association is weaker in older adults, which has created disagreement about the appropriateness of the threshold for these persons. In addition, the studies measuring these associations included relatively few outcomes and estimated GFR on the basis of creatinine level (eGFRcr), which may be less accurate in older adults.

OBJECTIVE

To evaluate associations in older adults between eGFRcr versus eGFR based on creatinine and cystatin C levels (eGFRcr-cys) and 8 outcomes.

DESIGN

Population-based cohort study.

SETTING

Stockholm, Sweden, 2010 to 2019.

PARTICIPANTS

82 154 participants aged 65 years or older with outpatient creatinine and cystatin C testing.

MEASUREMENTS

Hazard ratios for all-cause mortality, cardiovascular mortality, and kidney failure with replacement therapy (KFRT); incidence rate ratios for recurrent hospitalizations, infection, myocardial infarction or stroke, heart failure, and acute kidney injury.

RESULTS

The associations between eGFRcr-cys and outcomes were monotonic, but most associations for eGFRcr were U-shaped. In addition, eGFRcr-cys was more strongly associated with outcomes than eGFRcr. For example, the adjusted hazard ratios for 60 versus 80 mL/min/1.73 m2 for all-cause mortality were 1.2 (95% CI, 1.1 to 1.3) for eGFRcr-cys and 1.0 (CI, 0.9 to 1.0) for eGFRcr, and for KFRT they were 2.6 (CI, 1.2 to 5.8) and 1.4 (CI, 0.7 to 2.8), respectively. Similar findings were observed in subgroups, including those with a urinary albumin-creatinine ratio below 30 mg/g.

LIMITATION

No GFR measurements.

CONCLUSION

Compared with low eGFRcr in older patients, low eGFRcr-cys was more strongly associated with adverse outcomes and the associations were more uniform.

PRIMARY FUNDING SOURCE

Swedish Research Council, National Institutes of Health, and Dutch Kidney Foundation.

An increase in albuminuria is associated with a higher incidence of malignancies

Background

A single albuminuria measurement is reported to be an independent predictor of cancer risk. Whether change in albuminuria is also independently associated with cancer is not known.

Methods

We included 64 303 subjects of the Stockholm CREAtinine Measurements (SCREAM) project without a history of cancer and with at least two urine albumin-creatinine ratio (ACR) tests up to 2 years apart. Albuminuria changes were quantified by the fold-change in ACR over 2 years, and stratified into the absence of clinically elevated albuminuria (i.e. never), albuminuria that remained constant, and albuminuria that increased or decreased. The primary outcome was overall cancer incidence. Secondary outcomes were site-specific cancer incidences.

Results

During a median follow-up of 3.7 (interquartile range 3.6-3.7) years, 5126 subjects developed de novo cancer. After multivariable adjustment including baseline estimated glomerular filtration rate and baseline ACR, subjects with increasing ACR over 2 years had a 19% (hazard ratio 1.19; 95% confidence interval 1.08-1.31) higher risk of overall cancer compared with those who never had clinically elevated ACR. No association with cancer risk was seen in the groups with decreasing or constant ACR. Regarding site-specific cancer risks, subjects with increasing ACR or constant ACR had a higher risk of developing urinary tract and lung cancer. No other associations between 2-year ACR changes and site-specific cancers were found.

Conclusions

Increases in albuminuria over a 2-year period are associated with a higher risk of developing overall, urinary tract and lung cancer, independent of baseline kidney function and albuminuria. These data add important weight to the link that exists between albuminuria and cancer incidence.

Comparison of three creatinine-based equations to predict adverse outcome in a cardiovascular high-risk cohort: an investigation using the SPRINT research materials

Background

Novel creatinine-based equations have recently been proposed but their predictive performance for cardiovascular outcomes in participants at high cardiovascular risk in comparison to the established CKD-EPI 2009 equation is unknown.

Method

In 9361 participants from the United States included in the randomized controlled SPRINT trial, we calculated baseline estimated glomerular filtration rate (eGFR) using the CKD-EPI 2009, CKD-EPI 2021, and EKFC equations and compared their predictive value of cardiovascular events. The statistical metric used is the net reclassification improvement (NRI) presented separately for those with and those without events.

Results

During a mean follow-up of 3.1 ± 0.9 years, the primary endpoint occurred in 559 participants (6.0%). When using the CKD-EPI 2009, the CKD-EPI 2021, and the EKFC equations, the prevalence of CKD (eGFR <60 ml/min/1.73 m2 or >60 ml/min/1.73 m2 with an ACR ≥30 mg/g) was 37% vs. 35.3% (P = 0.02) vs. 46.4% (P < 0.001), respectively. The corresponding mean eGFR was 72.5 ± 20.1 ml/min/1.73 m2 vs. 73.2 ± 19.4 ml/min/1.73 m2 (P < 0.001) vs. 64.6 ± 17.4 ml/min/1.73 m2 (P < 0.001). Neither reclassification according to the CKD-EPI 2021 equation [CKD-EPI 2021 vs. CKD-EPI 2009: NRIevents: -9.5% (95% confidence interval (CI) -13.0% to -5.9%); NRInonevents: 4.8% (95% CI 3.9% to 5.7%)], nor reclassification according to the EKFC equation allowed better prediction of cardiovascular events compared to the CKD-EPI 2009 equation (EKFC vs. CKD-EPI 2009: NRIevents: 31.2% (95% CI 27.5% to 35.0%); NRInonevents: -31.1% (95% CI -32.1% to -30.1%)).

Conclusion

Substituting the CKD-EPI 2009 with the CKD-EPI 2021 or the EKFC equation for calculation of eGFR in participants with high cardiovascular risk without diabetes changed the prevalence of CKD but was not associated with improved risk prediction of cardiovascular events for both those with and without the event.

Comparison and evaluation of the 2009 and 2021 chronic kidney disease-epidemiological collaboration equations among Jordanian patients with type 2 diabetes mellitus

AIMS

This study compared the 2009 versus 2021 chronic kidney disease (CKD) Epidemiological Collaboration (CKD-EPI) equations to calculate estimated glomerular filtration rate (eGFR) among Jordanian patients with T2DM to assess their agreement and impact on CKD staging.

METHODS

This cross-sectional study included 2382 adult Jordanian patients with T2DM. The 2009 and 2021 CKD-EPI equations were used to calculate eGFR. Patients were reclassified according to kidney disease-Improving Global Outcomes (KDIGO) categories. Agreement between the equations was assessed using Bland-Altman plots and Lin's concordance correlation.

RESULTS

The 2021 equation significantly increased eGFR by a median of 2.1 mL/min/1.73 m2 (interquartile range: 0.6-3.6 mL/min/1.73 m2). However, there was significant agreement between equations (Kappa: 0.99; 95% confidence interval: 0.95-1.00), independent of age, sex, and the presence of hypertension. In total, 202 patients (8.5%) were reclassified to higher KDIGO categories using the 2021 equation, with category G3 being most affected. The overall prevalence of patients in the high to highest risk categories decreased (28.0% vs. 26.5%).

CONCLUSIONS

Although there was significant agreement with the 2009 equation, the 2021 equation increased eGFR and resulted in the reclassification of a subset of subjects according to KDIGO criteria. The uncertain impact of reducing high-risk category patients raises concerns about potential delays in referral and intervention, while holding the potential to enhance high-risk patient categorization, thus alleviating healthcare burden.

Kidney function predicts new-onset cardiorenal events and mortality in primary aldosteronism: approach of the 2021 race-free eGFR equation

Individuals with primary aldosteronism (PA) exhibit glomerular hyperfiltration, which may conceal underlying kidney damage. This observational cohort study enrolled 760 coronary artery disease-naive patients diagnosed with PA between January 1, 2007 and December 31, 2018 (male, 45%; mean age, 52.3 ± 11.9 years). The baseline estimated glomerular filtration rate (eGFR) was calculated using the 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which includes serum creatinine and cystatin C but omits the race variable. During a mean follow-up of 5.8 ± 3.2 years, new-onset composite cardiovascular events (total death, non-fatal myocardial infarction, and coronary revascularization procedure) occurred at a crude incidence rate of 10.9 per 1,000 person-years. Multivariable Cox proportional hazards analysis showed that baseline eGFR was independently associated with composite cardiovascular events (hazard ratio [HR], 0.98 [95% CI, 0.97-0.99]). Penalized splines smoothing in multivariable regression analysis demonstrated that the risk of composite cardiovascular events increased negatively and linearly when patients had a baseline eGFR less than 85 mL/min/1.73 m2. Patients with baseline eGFR <85 mL/min/1.73 m2 were independently associated with higher risks of composite cardiovascular events (HR, 2.39 [95% CI, 1.16-4.93]), all-cause mortality (HR, 4.63 [95% CI, 1.59-13.46]), and adverse kidney events (sub-distribution HR, 5.96 [95% CI, 3.69-9.62], with mortality as a competing risk). Our data support baseline eGFR as a predictor for new-onset adverse cardiorenal events and emphasizes the importance of the early detection of kidney function impairment in hypertensive patients with PA. We also firstly validate the 2021 race-free CKD-EPI eGFR equation in Asian patents with PA. Even with the glomerular hyperfiltration phenomenon, baseline eGFR in patients with primary aldosteronism is associated with subsequent cardiorenal outcomes. The results also firstly point to the validity of the 2021 race-free CKD-EPI eGFR equation in healthcare and clinical decision-making.

Performance of the race-free CKD-EPI creatinine-based eGFR equation in a Danish cohort with measured GFR

Background

In 2021, an updated Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation for estimated glomerular filtration rate (eGFR) without a coefficient for race (CKD-EPI21) was developed. The performance of this new equation has yet to be examined among specific patient groups.

Methods

We compared the performances of the new CKD-EPI21 equation and the 2009 equation assuming non-Black race (CKD-EPI09-NB) in patients with GFR measured by chromium-51-EDTA plasma clearance at Aarhus University Hospital in Denmark during 2010-18. We examined bias, accuracy, precision and correct classification of chronic kidney disease (CKD) stage using chromium-51-EDTA clearance as the reference standard. We assessed the performance in the total cohort, cancer patients and potential living kidney donors. We also assessed the performance stratified by CKD stage in the total cohort.

Results

In this predominantly white population, the CKD-EPI21 equation performed slightly better than the CKD-EPI09-NB equation in both the total cohort (N = 4668), and in cancer patients (N = 3313) and potential living kidney donors (N = 239). In the total cohort, the CKD-EPI21 equation demonstrated a slightly lower median absolute bias (-0.2 versus -4.4 mL/min/1.73 m2), and a similar accuracy, precision and correct classification of CKD stage compared with the CKD-EPI09-NB equation. When stratified by CKD stage, the CKD-EPI09-NB equation performed slightly better than the CKD-EPI21 equation among patients with a measured GFR (mGFR) <60 mL/min/1.73 m2.

Conclusions

In a selected cohort of Danish patients with mGFR, the CKD-EPI21 equation performed slightly better than the CKD-EPI09-NB equation except for patients with a mGFR <60 mL/min/1.73 m2, where CKD-EPI09-NB performed slightly better although the differences were considered clinically insignificant.

Diagnostic challenges of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of both type 1 and type 2 diabetes and the most common cause of the end-stage renal disease (ESRD). It has been evidenced that targeted interventions at an early stage of DKD can efficiently prevent or delay the progression of kidney failure and improve patient outcomes. Therefore, regular screening for DKD has become one of the fundamental principles of diabetes care. Long-established biomarkers such as serum-creatinine-based estimates of glomerular filtration rate and albuminuria are currently the cornerstone of diagnosis and risk stratification in routine clinical practice. However, their immanent biological limitations and analytical variations may influence the clinical interpretation of the results. Recently proposed new predictive equations without the variable of race, together with the evidence on better accuracy of combined serum creatinine and cystatin C equations, and both race- and sex-free cystatin C-based equation, have enabled an improvement in the detection of DKD, but also require the harmonization of the recommended laboratory tests, wider availability of cystatin C testing and specific approach in various populations. Considering the complex pathophysiology of DKD, particularly in type 2 diabetes, a panel of biomarkers is needed to classify patients in terms of the rate of disease progression and/or response to specific interventions. With a personalized approach to diagnosis and treatment, in the future, it will be possible to respond to DKD better and enable improved outcomes for numerous patients worldwide.

New and old GFR equations: a European perspective

Glomerular filtration rate (GFR) is estimated in clinical practice from equations based on the serum concentration of endogenous biomarkers and demographic data. The 2009 creatinine-based Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI2009) was recommended worldwide until 2021, when it was recalibrated to remove the African-American race factor. The CKD-EPI2009 and CKD-EPIcr2021 equations overestimate GFR of adults aged 18-30 years, with a strong overestimation in estimated GFR (eGFR) at age 18 years. CKD-EPICr2021 does not perform better than CKD-EPI2009 in US population, overestimating GFR in non-Black subjects, and underestimating it in Black subjects with the same magnitude. CKD-EPICr2021 performed worse than the CKD-EPI2009 in White Europeans, and provides no or limited performance gains in Black European and Black African populations. The European Kidney Function Consortium (EKFC) equation, which incorporates median normal value of serum creatinine in healthy population, overcomes the limitations of the CKD-EPI equations: it provides a continuity of eGFR at the transition between pediatric and adult care, and performs reasonably well in diverse populations, assuming dedicated scaling of serum creatinine (Q) values is used. The new EKFC equation based on cystatin C (EKFCCC) shares the same mathematical construction, namely, it incorporates the median cystatin C value in the general population, which is independent of sex and ethnicity. EKFCCC is therefore a sex-free and race-free equation, which performs better than the CKD-EPI equation based on cystatin C. Despite advances in the field of GFR estimation, no equation is perfectly accurate, and GFR measurement by exogenous tracer clearance is still required in specific populations and/or specific clinical situations.

Retaining Race in Chronic Kidney Disease Diagnosis and Treatment

The best overall measure of kidney function is glomerular filtration rate (GFR) as commonly estimated from serum creatinine concentrations (eGFRcr) using formulas that correct for the higher average creatinine concentrations in Blacks. After two decades of use, these formulas have come under scrutiny for estimating GFR differently in Blacks and non-Blacks. Discussions of whether to include race (Black vs. non-Black) in the calculation of eGFRcr fail to acknowledge that the original race-based eGFRcr provided the same CKD treatment recommendations for Blacks and non-Blacks based on directly (exogenously) measured GFR. Nevertheless, the National Kidney Foundation and the American Society of Nephrology Task Force on Reassessing the Inclusion of Race in Diagnosing Kidney Disease removed race in CKD treatment guidelines and pushed for the immediate adoption of a race-free eGFRcr formula by physicians and clinical laboratories. This formula is projected to negate CKD in 5.51 million White and other non-Black adults and reclassify CKD to less severe stages in another 4.59 million non-Blacks, in order to expand treatment eligibility to 434,000 Blacks not previously diagnosed and to 584,000 Blacks previously diagnosed with less severe CKD. This review examines: 1) the validity of the arguments for removing the original race correction, and 2) the performance of the proposed replacement formula. Excluding race in the derivation of eGFRcr changed the statistical bias from +3.7 to -3.6 ml/min/1.73m2 in Blacks and from +0.5 to +3.9 in non-Blacks, i.e., promoting CKD diagnosis in Blacks at the cost of restricting diagnosis in non-Blacks. By doing so, the revised eGFRcr greatly exaggerates the purported racial disparity in CKD burden. Claims that the revised formulas identify heretofore undiagnosed CKD in Blacks are not supported when studies that used kidney failure replacement therapy and mortality are interpreted as proxies for baseline CKD. Alternatively, a race-stratified eGFRcr (i.e., separate equations for Blacks and non-Blacks) would provide the least biased eGFRcr for both Blacks and non-Blacks and the best medical treatment for all patients.

Long and Short-Term Effects of Hypothermic Machine Perfusion vs. Cold Storage on Transplanted Kidneys from Expanded Criteria Donors-A Matched Comparison Study

Hypothermic machine perfusion (HMP) has been shown to reduce delayed graft function (DGF)-rates in kidneys from expanded criteria donors (ECD) and may increase graft survival compared with static cold storage (SCS). This single-center, retrospective observational study aimed to evaluate this effect. The primary endpoint was the DGF-rate, defined as the use of dialysis in the first postoperative week, excluding the first 24 h. The main secondary endpoint was graft survival at 5 years. Recipients of ECD-kidneys between 2013 and 2021 with ≤2 grafts were included (n = 438). The SCS-kidneys were marginal-matched by propensity score to the HMP-group for donor age, cold ischemia time, and graft number. Multivariable adjusted analysis for confounders in the unmatched cohort and caliper-based ID-matching constituted sensitivity analyses. HMP showed a trend to lower DGF-rate in the marginal-matched comparison (9.2% vs. 16.1%, p = 0.063). This was strengthened by a significant benefit observed for HMP in both the sensitivity analyses: an adjusted OR of 0.45 (95% CI: 0.24; 0.84; p = 0.012) in the multivariable analysis and DGF-rate of 8.7% vs. 17.4% (p = 0.024) after ID-matching. The 5-year graft survival rate was >90% in both groups, with no benefit using HMP (HR = 0.79; 95% CI:0.39-1.16; p = 0.52). Our results suggest that HMP may be effective in decreasing DGF-rates, however, without any significant benefit in graft survival.

Development and validation of a new equation based on plasma creatinine and muscle mass assessed by CT scan to estimate glomerular filtration rate: a cross-sectional study

Background

Inter-individual variations of non-glomerular filtration rate (GFR) determinants of serum creatinine, such as muscle mass, account for the imperfect performance of estimated GFR (eGFR) equations. We aimed to develop an equation based on creatinine and total lumbar muscle cross-sectional area measured by unenhanced computed tomography scan at the third lumbar vertebra.

Methods

The muscle mass-based eGFR (MMB-eGFR) equation was developed in 118 kidney donor candidates (iohexol clearance) using linear regression. Validation cohorts included 114 healthy subjects from another center (⁵¹Cr-EDTA clearance, validation population 1), 55 patients with chronic diseases (iohexol, validation population 2), and 60 patients with highly discordant creatinine and cystatin C-based eGFR, thus presumed to have atypical non-GFR determinants of creatinine (⁵¹Cr-EDTA, validation population 3). Mean bias was the mean difference between eGFR and measured GFR, precision the standard deviation (SD) of the bias, and accuracy the percentage of eGFR values falling within 20% and 30% of measured GFR.

Results

In validation population 1, performance of MMB-eGFR was not different from those of CKD-EPI_Cr2009 and CKD-EPI_Cr2021. In validation population 2, MMB-eGFR was unbiased and displayed better precision than CKD-EPI_Cr2009, CKD-EPI_Cr2021 and EKFC (SD of the biases: 13.1 vs 16.5, 16.8 and 15.9 mL/min/1.73 m²). In validation population 3, MMB-eGFR had better precision and accuracy {accuracy within 30%: 75.0% [95% confidence interval (CI) 64.0-86.0] vs 51.5% (95% CI 39.0-64.3) for CKD-EPI_Cr2009, 43.3% (95% CI 31.0-55.9) for CKD-EPICr2021, and 53.3% (95% CI 40.7-66.0) for EKFC}. Difference in bias between Black and white subjects was -2.1 mL/min/1.73 m² (95% CI -7.2 to 3.0), vs -8.4 mL/min/1.73 m² (95% CI -13.2 to -3.6) for CKD-EPI_Cr2021.

Conclusion

MMB-eGFR displayed better performances than equations based on demographics, and could be applied to subjects of various ethnic backgrounds.

Chronic kidney disease in the elderly and frail patient: perspectives with opinions and comments

Chronic kidney disease is common in elderly and frail people. The importance of age in staging chronic kidney disease is discussed as well as the possible constraints of staging what is actually a 'continuum' of disease progression. Frailty is a biological state characterized by the decline of several physiological systems and strongly correlated with adverse health outcomes, including mortality. Frailty is measured by the Comprehensive Geriatric Assessment, which focuses on quantitative rating scales that determine not only the clinical profile and pathological risk of frail individuals, but also their residual capacities, functional status, and quality of life. There is circumstantial evidence that Comprehensive Geriatric Assessment can improve both survival and quality of life in elderly chronic kidney disease patients. Despite the long list of emerging risk factors and markers of chronic kidney disease progression, it is the authors' opinion that a single biochemical parameter can hardly cover the complexity of chronic kidney disease in elderly and frail patients. Among the numerous clinical scores proposed, the European Renal Best Practice guidelines recommend the Renal Epidemiology and Information Network score and the Kidney Failure Risk Equations. The former provides a reasonable estimate of short-term mortality risk, the latter provides the risk of chronic kidney disease progression. In conclusion, the elderly individual with advanced chronic kidney disease is often comorbid and frail with peculiarities in terms of disease grading, clinical assessment and monitoring. The time has come to reshape the care of this growing number of patients by focusing on multidisciplinary teams both in the hospital and in the community.

The new, race-free, Chronic Kidney Disease Epidemiology Consortium (CKD-EPI) equation to estimate glomerular filtration rate: is it applicable in Europe? A position statement by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM)

The EFLM recommends not to implement the race-free Chronic Kidney Disease Epidemiology Consortium (CKD-EPI) equation in European laboratories and to keep the 2009 version of the CKD-EPI equation, without applying a race correction factor. This recommendation is completely in line with a recent Editorial published by the European Renal Association who has also proposed to change to a novel equation only when it has considerably better performance, trying to reach global consensus before implementing such a new glomerular filtration rate (GFR) estimation equation. In Europe, this equation could be for instance the new European Kidney Function Consortium (EKFC) equation, which is population-specific, developed from European cohorts and accurate from infants to the older old. Beyond serum creatinine, the estimating equations based on cystatin C will probably gain in popularity, especially because cystatin C seems independent of race. Finally, we must keep in mind that all GFR equations remain an estimation of GFR, especially rough at the individual level. Measuring GFR with a reference method, such as iohexol clearance, remains indicated in specific patients and/or specific situations, and here also, the role of the clinical laboratories is central and should still evolve positively in the future.

[Diabetic kidney disease (update 2023) : Position paper of the Austrian Diabetes Association and the Austrian Society for Nephrology]

Epidemiological investigations have shown that approximately 2-3% of all Austrians have diabetes mellitus with renal involvement, leaving 250,000 people in Austria affected. The risk of occurrence and progression of this disease can be attenuated by lifestyle interventions as well as optimization of blood pressure, blood glucose control and special drug classes. The present article represents the joint recommendations of the Austrian Diabetes Association and the Austrian Society of Nephrology for the diagnostic and treatment strategies of diabetic kidney disease.

Circulating Fibroblast Growth Factor-23 Levels Can Predict Rapid Kidney Function Decline in a Healthy Population: A Community-Based Study

BACKGROUND

Fibroblast growth factor-23 (FGF-23) associates with decreased kidney function in patients with chronic kidney disease (CKD). However, the correlation between circulating FGF-23 levels and the rate of renal function decline in healthy individuals is largely unknown. We aimed to evaluate the predictive performance of FGF-23 for rapid kidney function decline (RKFD) in a community-based study.

METHODS

A total of 2963 people residing in northern Taiwan were enrolled from August 2013 to May 2018 for an annual assessment of kidney function for five years. The baseline estimated glomerular filtration rates (eGFR) were calculated using the 2009 and 2021 Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, which aggregates the values of serum creatinine and cystatin C (eGFRcr-cys). The outcome was RKFD-a 15% decrease in estimated glomerular filtration rate (eGFR) within the first four years, and a reduction in eGFR without improvement in the 5th year. A generalized additive model (GAM) was used to determine the cut-off value of FGF-23 to predict RKFD.

RESULTS

The incidence of RKFD was 18.0% (114/634). After matching for age and sex at a 1:1 ratio, a total of 220 subjects were analyzed. eGFRcr-cys was negatively correlated with total vitamin D level but seemed irrelevant to FGF-23. Multivariable logistic regression analysis showed that FGF-23, eGFRcr-cys, and urine albumin-to-creatinine ratio (UACR) were independent predictors of the possibility of RKFD. FGF-23 showed the best predictive performance for RKFD (AUROC: 0.803), followed by baseline eGFRcr-cys (AUROC: 0.639) and UACR (AUROC: 0.591). From the GAM, 32 pg/mL was the most appropriate cut-off value of FGF-23 with which to predict RKFD. The subgroup and sensitivity analyses showed consistent results that high-FGF-23 subjects had higher risks of RKFD.

CONCLUSIONS

Circulating FGF-23 level could be a helpful predictor for RKFD in this community-based population.