2009 CKD-EPI glomerular filtration rate estimation in Black individuals outside the United States: a systematic review and meta-analysis

Is race adjustment necessary to estimate glomerular filtration rate in South Brazilians?

BACKGROUND AND AIMS

Race coefficients (RC) in equations to estimate glomerular filtration rate (GFR) have been highly questioned. We aimed to evaluate the performance of three equations, namely 2009 Chronic Kidney Disease Epidemiology Collaboration (2009 CKD-EPI), 2021 CKD-EPI, and European Kidney Function Consortium (EKFC) in self-reported Black and White Brazilians.

MATERIALS AND METHODS

Our cross-sectional study compared estimated GFR (eGFR) with 51Cr-EDTA measured GFR (mGFR) in healthy adults, patients with type 2 diabetes mellitus with or without chronic kidney disease (CKD), and in non-diabetic individuals with CKD. The performance of these equations was assessed using Bland-Altman plots, Lin's concordance correlation coefficient (CCC), bias, P30, and P15 accuracy.

RESULTS

Three hundred six White adults (aged 53 ± 17 years, 55% women, mean mGFR: 83 ± 32 mL/min/1.73 m2) and 48 Black participants (aged 53 ± 17 years, 58% women, mGFR: 90 ± 34 mL/min/1.73 m2) were included. No equation achieved the desirable P30 accuracy value of 90%, neither in White (2009 CKD-EPI:78%, 2021 CKD-EPI:76% and EKFC:77%, p = 0.368) nor in Black volunteers (respective values of 77%, 75%, and 77%; p = 0.882). The 2009 CKD-EPI showed the best performance in Black participants (bias: 4.04; CCC: 0.848), whereas the 2021 CKD-EPI performed better in Whites, with smaller bias (1.45), and better concordance correlation coefficient (0.790). The EKFC presented the worst performance. All equations underdiagnosed advanced CKD in White participants, but not in Black.

CONCLUSIONS

The 2021 CKD-EPI does not outperform the 2009 CKD-EPI. Instead, it underestimated the occurrence of CKD in White participants. Thus, we do not recommend replacing the 2009 with the new 2021 CKD-EPI in the Brazilian population.

Data mining of reference intervals for serum creatinine: an improvement in glomerular filtration rate estimating equations based on Q-values

OBJECTIVES

Glomerular filtration rate (GFR) estimating equations based on rescaled serum creatinine (SCr/Q) have shown better performance, where Q represents the median SCr for age- and sex-specific healthy populations. However, there remains a scarcity of investigations in China to determine this value. We aimed to develop Chinese age- and sex-specific reference intervals (RIs) and Q-values for SCr and to validate the equations incorporating new Q-values.

METHODS

We included 117,345 adults from five centers for establishing RIs and Q-values, and 3,692 participants with reference GFR (rGFR, 99mTc-DTPA renal dynamic imaging measurement) for validation. Appropriate age partitioning was determined using the decision tree method. Lower and upper reference limits and medians were calculated using the refineR algorithm, and Q-values were determined accordingly. We evaluated the full age spectrum (FAS) and European Kidney Function Consortium (EKFC) equations incorporating different Q-values considering bias, precision (interquartile range, IQR), and accuracy (percentage of estimates within ±20 % [P20] and ±30 % [P30] of rGFR).

RESULTS

RIs for males were: 18-79 years, 55.53-92.50 μmol/L; ≥80 years, 54.41-96.43 μmol/L. RIs for females were: 18-59 years, 40.42-69.73 μmol/L; 60-79 years, 41.16-73.69 μmol/L; ≥80 years, 46.50-73.20 μmol/L. Q-values were set at 73.82 μmol/L (0.84 mg/dL) for males and 53.80 μmol/L (0.61 mg/dL) for females. After validation, we found that the adjusted equations exhibit less bias, improved precision and accuracy, and increased agreement of GFR categories.

CONCLUSIONS

We determined Chinese age- and sex-specific RIs and Q-values for SCr. The adjustable Q-values provide an effective alternative to obtain valid equations for estimating GFR.

Estimated glomerular filtration rate in clinical practice: Consensus positioning of the Brazilian Society of Nephrology (SBN) and Brazilian Society of Clinical Pathology and Laboratory Medicine (SBPC/ML)

Chronic kidney disease (CKD) represents one of today's main public health problems. Serum creatinine measurement and estimation of the glomerular filtration rate (GFR) are the main tools for evaluating renal function. There are several equations to estimate GFR, and CKD-EPI equation (Chronic Kidney Disease - Epidemiology) is the most recommended one. There are still some controversies regarding serum creatinine measurement and GFR estimation, since several factors can interfere in this process. An important recent change was the removal of the correction for race from the equations for estimating GFR, which overestimated kidney function, and consequently delayed the implementation of treatments such as dialysis and kidney transplantation. In this consensus document from the Brazilian Societies of Nephrology and Clinical Pathology and Laboratory Medicine, the main concepts related to the assessment of renal function are reviewed, as well as possible existing controversies and recommendations for estimating GFR in clinical practice.

Comparison of glomerular filtration rate estimating equations in older adults: A systematic review and meta-analysis

BACKGROUND

Debates persist regarding the performance of existing glomerular filtration rate (GFR) estimating equations in older individuals. We performed this meta-analysis to assess the accuracy and bias of six commonly used equations, including the Chronic Kidney Disease Epidemiology Collaboration creatinine equation (CKD-EPICr) and its combination with cystatin C (CKD-EPICr-Cys), with the corresponding pair of the Berlin Initiative Study equations (BIS1 and BIS2) and the Full Age Spectrum equations (FASCr and FASCr-Cys).

METHODS

PubMed and the Cochrane Library were searched for studies comparing estimated GFR (eGFR) with measured GFR (mGFR). We analyzed the difference in P30 and bias among the six equations and investigated subgroups based on the area (Asian and non-Asian), mean age (60-74 years and ≥75 years), and levels of mean mGFR (<45 mL/min/1.73m2 and ≥45 mL/min/1.73m2).

RESULTS

27 studies with 18,112 participants were included, all reporting P30 and bias. BIS1 and FASCr exhibited significantly higher P30 than CKD-EPICr. While no significant differences were observed between FASCr and BIS1, or among the three combined equations in terms of either P30 or bias. Subgroup analyses revealed FASCr and FASCr-Cys achieved better results in most situations. However, in the subgroup of mGFR<45 mL/min/1.73m2, CKD-EPICr-Cys had relatively higher P30 and significantly smaller bias.

CONCLUSIONS

Overall, BIS and FAS provided relatively more accurate estimates of GFR than CKD-EPI in older adults. FASCr and FASCr-Cys may be better suited for various conditions, while CKD-EPICr-Cys would be a better option for older individuals with impaired renal function.

Early diagnosis of chronic kidney disease in patients with diabetes in France: multidisciplinary expert opinion, prevention value and practical recommendations

Diabetes is the leading cause of end-stage kidney disease (ESKD), accounting for approximately 50% of patients starting dialysis. However, the management of these patients at the stage of chronic kidney disease (CKD) remains poor, with fragmented care pathways among healthcare professionals (HCPs). Diagnosis of CKD and most of its complications is based on laboratory evidence. This article provides an overview of critical laboratory evidence of CKD and their limitations, such as estimated glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio (UACR), Kidney Failure Risk Equation (KFRE), and serum potassium. eGFR is estimated using the CKD-EPI 2009 formula, more relevant in Europe, from the calibrated dosage of plasma creatinine. The estimation formula and the diagnostic thresholds have been the subject of recent controversies. Recent guidelines emphasized the combined equation using both creatinine and cystatin for improved estimation of GFR. UACR on a spot urine sample is a simple method that replaces the collection of 24-hour urine. Albuminuria is the preferred test because of increased sensitivity but proteinuria may be appropriate in some settings as an alternative or in addition to albuminuria testing. KFRE is a new tool to estimate the risk of progression to ESKD. This score is now well validated and may improve the nephrology referral strategy. Plasma or serum potassium is an important parameter to monitor in patients with CKD, especially those on renin-angiotensin-aldosterone system (RAAS) inhibitors or diuretics. Pre-analytical conditions are essential to exclude factitious hyperkalemia. The current concept is to correct hyperkalemia using pharmacological approaches, resins or diuretics to be able to maintain RAAS blockers at the recommended dose and discontinue them at last resort. This paper also suggests expert recommendations to optimize the healthcare pathway and the roles and interactions of the HCPs involved in managing CKD in patients with diabetes.

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.

Validation of the European Kidney Function Consortium Equation in Chinese Adult Population: An Equation Standing on the Shoulders of Predecessors

BACKGROUND

Equations based on serum creatinine (SCr) have been extensively applied to estimate glomerular filtration rate (GFR), but their performance is debatable. In 2021, the European Kidney Function Consortium (EKFC) published one novel SCr-based formula, which combined the feature of Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and full age spectrum (FAS) equations, but its potential applications remain unknown. We seek to assess the appropriateness of the three equations in Chinese adults.

METHODS

A total of 3,692 participants (median age, 54 years) were included. Reference GFR (rGFR) was measured by the 99mTc-DTPA renal dynamic imaging method. Estimated GFR (eGFR) was calculated by the CKD-EPI, FAS, and EKFC equations. Correlation coefficients and Bland-Altman analysis were adopted to evaluate their validity. The performance was assessed in subgroups according to age, sex, rGFR, and SCr, considering the bias, accuracy, and precision.

RESULTS

The average rGFR was 74.2 mL/min/1.73 m2. eGFR by EKFC showed a relatively stronger correlation with rGFR (R = 0.749) and a larger area under the receiver operating characteristic curve (0.902). EKFC was significantly less biased and exhibited the highest P30 in the entire population (bias = 3.61, P30 = 73.3%). It also performed well in all analyzed subgroups, especially in participants with normal or slightly impaired renal function (rGFR≥60 mL/min/1.73 m2), and low SCr.

CONCLUSIONS

Compared to the other two SCr-based formulas, EKFC performed better in the Chinese. Thus, it might serve as a good alternative, until a more suitable formula is developed for the Chinese population.