Comparison of the 2021 and 2009 Chronic Kidney Disease Epidemiology Collaboration Creatinine equation for estimated glomerular filtration rate in a Chinese population

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+.

Clinical Impacts of Implementing the 2021 Race-Free Chronic Kidney Disease Epidemiology Collaboration Estimated Glomerular Filtration Rate

BACKGROUND

Estimated glomerular filtration rate (eGFR) has become incorporated into multiple clinical management situations. Historically, equations included a Black race coefficient, which lacked biological plausibility and created potential to exacerbate health disparities. A new equation created in 2021 changed the weighting of age, sex, and creatinine by modeling against a diverse cohort and removing the Black race coefficient.

CONTENT

A variety of clinical outcomes including kidney disease risk stratification, medication dosing, patient eligibility for clinical trials, and kidney donation are impacted by implementation of the new equation. Nearly 2 years after its initial publication, many studies have reported on observed analytical performance of the 2021 eGFR determined as diagnostic concordance and percentage of estimates within 30% of measured GFR. Additionally, the potential clinical impacts following adoption of the new eGFR among different patient populations has also been reported. Here we review these studies with a focus on assessing the data associated with the transition from 2009 to 2021 Chronic Kidney Disease Epidemiology Collaboration equations.

SUMMARY

The reported interindividual variation in eGFR performance is significantly larger than any potential benefit derived from race coefficients. Both the 2021 eGFR and the 2009 eGFR analytical performance fall short of the validation cohort performance in most cohorts. However, the 2021 analytical is similar or better than the 2009 eGFR in most cohorts. Implementing the 2021 eGFR will remove a systematic overestimation of kidney function among Black patients.

Estimating Glomerular Filtration Rate in China: Is the European Kidney Function Consortium (EKFC) Equation the Solution?

The new European Kidney Function Consortium (EKFC) creatinine-based equation has been developed to be applicable over the entire age range (from 2 to 100 years) without any loss of performance in young adults and without loss of continuity in estimating glomerular filtration rate (GFR) between adolescents and adults. This goal is obtained by better taking into account the relationship between serum creatinine (SCr) and age in the estimating GFR model. This is accomplished by rescaling SCr, namely, dividing SCr by so-called Q value which is the median normal value of SCr concentration in a given healthy population. The better performance of the EKFC equation, compared to the current equations, has been shown in large European and African cohorts. Such good results are also suggested in cohorts from China, including in the current issue of Nephron. The good performance of the EKFC equation is observed, especially when the authors used a specific Q value for their populations notwithstanding GFR was measured by a controversial method. Using a population-specific Q value could make the EFKC equation universally applicable.