A comparison between 2017 FAS and 2012 CKD-EPI equations: a multi-center validation study in Chinese adult population

GFRs in Chinese CKD: A systematic review

PURPOSE

This was an evidence-based study to assess which creatinine-based equation was most useful for estimated glomerular filtration rate (eGFR) in Chinese adults with chronic kidney disease (CKD).

METHODS

Multiple databases were searched to collect relevant studies on creatinine-based eGFR equations for Chinese adults with CKD in Chinese and English from January 2009 to January 2023, using "glomerular filtration rate", "GFR equations", "Chinese CKD", "chronic kidney disease", "equation development" and "equation validation". The quality of each study was assessed using the diagnostic test accuracy review by RevMan 5.4 software. The equation name, study publication year, first author, reference method for eGFR, CKD numbers, age (age ranges) of individuals, mGFR value, bias, precision, and 30% accuracy (P30) of each included equation were recorded accordingly by 2 independent investigators.

RESULTS

Of the 838 studies identified, 23 studies based on 6 creatinine-based GFR equations were included in the present review, ie, the CKD-EPI, Asian modified CKD-EPI, FAS, EKFC, Xiangya, and BSI1 equations. A total of 2979 CKD patients were included for FAS equation external assessment, and the total P30 was 72.6 %; 970 CKD patients for the EKFC equation, and the total P30 was 73.1 %. 1778 CKD patients (≥60 years of age) with a mean eGFR from 39.7 to 47.6 mL/min/1.73 m2 were pooled to assess the prediction accuracy of the BSI1 equation and demonstrated that the bias was small (-3.8-3.5 mL/min/1.73 m2), the precision was excellent (10.2-16.8 mL/min/1.73 m2), and the total P30 was 69.6 %.

CONCLUSIONS

Currently, the FAS and EKFC equations have higher P30 for eGFR among Chinese adult CKD patients. The bias and precision of BSI1 formulas was acceptable for eGFR in elderly ≥ 60 years of age, while the P30 was relatively low. Therefore, there is a clinical need to develop more accurate equations for eGFR in older CKD adults. While promising, these findings require further validation in large well controlled clinical studies.

Different equations for estimating age-related changes of glomerular filtration rate in the healthy population

BACKGROUND

Identifying age-related trend of estimated glomerular filtration rate (eGFR) is necessary to assess whether kidney function is healthily aging. This study aimed to investigate the application of CKD-EPI, FAS, and Xiangya equations for the aging estimation of eGFR in the healthy Chinese individuals.

METHODS

A total of 36,911 healthy individuals were enrolled in this study. We grouped every ten years to observe the trend of eGFR with aging and investigated decline rate of it by general linear regression analysis in each age-groups. Agreement between equations was determined by intraclass correlation coefficient (ICC) and Bland-Altman plot. We calculated reference interval in each age-group. We further analyzed above statistical indicators in males and females.

RESULTS

The eGFR by CKD-EPI, and Xiangya equation started to decline from the age of 18. Whereas eGFR by FAS equation remained stable under 40 years, then decreased more rapidly. Compared with males, the females had a higher level but a faster decline rate of eGFR with aging. Agreement analysis revealed good agreement between CKD-EPI and FAS equations (ICC 0.818-0.920). Agreement between Xiangya and CKD-EPI or FAS equations was poor to moderate in most of the population under 70 years old (ICC 0.282-0.786), but good in individuals above 70 years (ICC 0.769-0.881).

CONCLUSIONS

The trend of eGFR with aging was different by CKD-EPI, FAS, and Xiangya equations in the healthy Chinese. It may be necessary to take these equations- or age-related differences into consideration when assessing kidney function in primary health care and 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.

Comparison of estimated glomerular filtration rate equations based on serum creatinine-, cystatin C- and creatinine-cystatin C in elderly Chinese patients

BACKGROUND

This study aimed to further evaluate the accuracy of eleven GFR equations in different subgroups of an elderly Chinese hospitalized population.

METHODS

All participants of the study were divided into seven separate groups including age-subgroup, sex-subgroup, GFR Staging-subgroup and whether combined with diabetic, hypertensive, coronary heart disease (CHD) and cerebrovascular disease. Referring to Tc-99m-DTPA dual plasma sample clearance method, six serum creatinine (Cr)-based [Cockcroft-Gault (CG), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI_Cr), Lund-Malmö Revised (LMR), Berlin Initiative Study (BIS1), Full Age Spectrum (FAS_Cr) and European Kidney Function Consortium (EKFC)], two serum cystatin C(Cys)-based (CKD-EPI_Cys and FAS_Cys), and three Cr-Cys combination based (CKD-EPI_Cr-Cys, BIS2 and FAS_Cr-Cys) equations were employed. Bias, interquartile range of the median difference (IQR), P30, and GFR misclassification rate were calculated to compare the performance of the selected equations.

RESULTS

A total of 359 elderly Chinese patients were enrolled. Overall, median mGFR was 36.91(25.26,56.32)ml/min/1.73 m². Smaller biases (ml/min/1.73 m²) were shown in CKD-EPI_Cr and BIS1 equations (0.75 and 0.61). IQR (ml/min/1.73m²) was least with BIS2 equation and FAS_Cr-Cys equation (10.34 and 10.65). For accuracy (P30), performance of FAS_Cr-Cys, BIS2, and BIS1 equation was superior (78.3%, 78.0%, and 74.7%, respectively). In terms of RMSE (ml/min/1.73 m²), BIS1 and FAS_Cr-Cys equation performed better (12.44 and 12.51).

CONCLUSIONS

Overall, this study showed that the eGFR equations were less accurate in the diabetic and non-hypertension group than in the non-diabetic and hypertension group, respectively. Among all enrolled equations, the BIS2 and FAS_Cr-Cys equations might be the best choice to evaluate glomerular filtration rate in Chinese elderly patients.

Optimal Glomerular Filtration Rate Equations for Various Age Groups, Disease Conditions and Ethnicities in Asia: A Systematic Review

(1) Background: The performance of estimated glomerular filtration rate (eGFR) equations in the Asian population has been widely questioned. The primary objective of this study was to gather evidence regarding optimal GFR equations in Asia for various age groups, disease conditions, and ethnicities. The secondary objective was to see whether the equations based on the combination of creatinine and cystatin C biomarkers if employed are satisfactory across different age groups and disease conditions in various ethnicities in Asia compared to those based on either of the single biomarkers. (2) Methods: Validation studies that had both creatinine and cystatin C-based equations either alone or in combination, validated in specific disease conditions, and those which compared the performance of these equations with exogenous markers were eligible only. The bias, precision, and 30% accuracy (P30) of each equation were recorded accordingly. (3) Results: Twenty-one studies consisting of 11,371 participants were included and 54 equations were extracted. The bias, precision, and P30 accuracies of the equations ranged from -14.54 to 9.96 mL/min/1.73 m2, 1.61 to 59.85 mL/min/1.73 m2, and 4.7% to 96.10%. The highest values of P30 accuracies were found for the JSN-CKDI equation (96.10%) in Chinese adult renal transplant recipients, for the BIS-2 equation (94.5%) in Chinese elderly CKD patients, and Filler equation (93.70%) also in Chinese adult renal transplant recipients. (4) Conclusions: Optimal equations were identified accordingly and it was proven that combination biomarker equations are more precise and accurate in most of the age groups and disease conditions. These can be considered equations of choice for the specific age groups, disease conditions, and ethnicities within Asia.

Choosing an appropriate glomerular filtration rate estimating equation: role of body mass index

Background

We aimed to investigate the accuracy of different equations in evaluating estimated glomerular filtration rate (eGFR) in a Chinese population with different BMI levels.

Methods

A total of 837 Chinese patients were enrolled, and the eGFRs were calculated by three Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, three full-age spectrum (FAS) equations and two Modification of Diet in Renal Disease (MDRD) equations. Results of measured GFR (mGFR) by the 99Tcm-diathylenetriamine pentaacetic acid (99Tcm-DTPA) renal dynamic imaging method were the reference standards. According to BMI distribution, the patients were divided into three intervals: below 25th(BMI_P25), 25th to 75th(BMI_P25–75) and over 75th percentiles (BMI_P75).

Results

The medium BMI of the three BMI intervals were 20.9, 24.8 and 28.9 kg/m², respectively. All deviations from mGFR (eGFR) were correlated with BMI (p < 0.05). The percentage of cases in which eGFR was within mGFR ±30% (P30) was used to represent the accuracy of each equation. Overall, eGFR_{FAS_Cr_CysC} and eGFREPI_Cr_2009 performed similarly, showing the best agreement with mGFR among the eight equations in Bland-Altman analysis (biases: 4.1 and − 4.2 mL/min/1.73m², respectively). In BMI_P25 interval, eGFR_{FAS_Cr} got − 0.7 of the biases with 74.2% of P30, the kappa value was 0.422 in classification of CKD stages and the AUC₆₀ was 0.928 in predicting renal insufficiency, and eGFREPI_Cr_2009 got 2.3 of the biases with 71.8% of P30, the kappa value was 0.418 in classification of CKD stages and the AUC₆₀ was 0.920 in predicting renal insufficiency. In BMI_P25–75 interval, the bias of eGFR_{FAS_Cr_CysC} was 4.0 with 85.0% of P30, the kappa value was 0.501 and the AUC₆₀ was 0.941, and eGFR_{FAS_Cr_CysC} showed balanced recognition ability of each stage of CKD (62.3, 63.7, 68.0, 71.4 and 83.3% respectively). In BMI_P75 interval, the bias of eGFR_{EPI_Cr_CysC_2012} was 3.8 with 78.9% of P30, the kappa value was 0.484 the AUC₆₀ was 0.919, and eGFR_{EPI_Cr_CysC_2012} equation showed balanced and accurate recognition ability of each stage (60.5, 60.0, 71.4, 57.1 and 100% respectively). In BMI_P75 interval, the bias of eGFR_{FAS_Cr_CysC} was − 1.8 with 78.5% of P30, the kappa value was 0.485, the AUC₆₀ was 0.922. However, the recognition ability of each stage of eGFR_{FAS_Cr_CysC} eq. (71.1, 61.2, 70.0, 42.9 and 50.0% respectively) was not as good as GFR_{EPI_Cr_CysC_2012} equation.

Conclusion

For a Chinese population, we tend to recommend choosing eGFR_{FAS_Cr} and eGFR_{EPI_Cr_2009} when BMI was around 20.9, eGFR_{FAS_Cr_CysC} when BMI was near 24.8, and eGFR_{EPI_Cr_CysC_2012} when BMI was about 28.9.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02395-x.

Comparative performance of FAS equation and Asian modified CKD-EPI in the determination of GFR in Chinese patients with CKD with the 99mTc-DTPA plasma clearance as the reference method

BACKGROUND

Glomerular filtration rate (GFR) is a useful index in many clinical conditions. However, very few studies have assessed the performance of full age spectrum (FAS) equation and the Asian modified Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation in the approximation of GFR in Chinese patients with chronic kidney disease.

OBJECTIVE

This study aimed to compare the diagnostic performance of the above two creatinine-based equations.

METHODS

A well designed single-center cross-sectional study was performed and the GFR was determined by 3 methods separately in the same day: technetium-99m-diethylene triamine pentaacetic acid (^99mTc-DTPA) dual plasma sample clearance method (mGFR); FAS equation method; Asian modified CKD-EPI equation method. The gold standard method was the mGFR. Equations performance criteria considered correlation coefficient, bias, precision, accuracy and the ability to detect the mGFR less than 60ml/min/1.73m².

RESULTS

A total of 160 patients were enrolled. The diagnostic performance of FAS showed no significant difference in the correlation coefficient (0.89 vs 0.89), precision (15.9 vs 16.1ml/min/1.73m²), accuracy (75.0% vs 76.3%) and the ability to detect the mGFR less than 60ml/min/1.73m² (0.94 vs 0.94) compared with the Asian modified CKD-EPI equation in all participants. The FAS showed a negative bias, while the new CKD-EPI equation showed a positive bias (-1.20 vs 1.30ml/min/1.73m², P<0.001). However, they were all near to zero. In the mGFR<60ml/min/1.73m² subgroup and mGFR>60ml/min/1.73m² subgroup were consistent with that in the whole cohort. The precision and accuracy decreased when GFR>60ml/min/1.73m² in both equations.

CONCLUSIONS

The FAS equation and the Asian modified CKD-EPI equation had similar performance in determining the glomerular filtration rate in the Chinese patients with chronic kidney disease. Both the FAS equation and Asian modified CKD-EPI can be a satisfactory method and may be the most suitable creatinine-based equation.

Comparative performance of FAS equation and Asian modified CKD-EPI in the determination of GFR in Chinese patients with CKD with the 99mTc-DTPA plasma clearance as the reference method

BACKGROUND

Glomerular filtration rate (GFR) is a useful index in many clinical conditions. However, very few studies have assessed the performance of full age spectrum (FAS) equation and the Asian modified Chronic Kidney Disease-Epidemiology Collaboration (CKD-EPI) equation in the approximation of GFR in Chinese patients with chronic kidney disease.

OBJECTIVE

This study aimed to compare the diagnostic performance of the above two creatinine-based equations.

METHODS

A well designed single-center cross-sectional study was performed and the GFR was determined by 3 methods separately in the same day: technetium-99m-diethylene triamine pentaacetic acid (^99mTc-DTPA) dual plasma sample clearance method (mGFR); FAS equation method; Asian modified CKD-EPI equation method. The gold standard method was the mGFR. Equations performance criteria considered correlation coefficient, bias, precision, accuracy and the ability to detect the mGFR less than 60ml/min/1.73m².

RESULTS

A total of 160 patients were enrolled. The diagnostic performance of FAS showed no significant difference in the correlation coefficient (0.89 vs 0.89), precision (15.9 vs 16.1ml/min/1.73m²), accuracy (75.0% vs 76.3%) and the ability to detect the mGFR less than 60ml/min/1.73m² (0.94 vs 0.94) compared with the Asian modified CKD-EPI equation in all participants. The FAS showed a negative bias, while the new CKD-EPI equation showed a positive bias (-1.20 vs 1.30ml/min/1.73m², P<0.001). However, they were all near to zero. In the mGFR<60ml/min/1.73m² subgroup and mGFR>60ml/min/1.73m² subgroup were consistent with that in the whole cohort. The precision and accuracy decreased when GFR>60ml/min/1.73m² in both equations.

CONCLUSIONS

The FAS equation and the Asian modified CKD-EPI equation had similar performance in determining the glomerular filtration rate in the Chinese patients with chronic kidney disease. Both the FAS equation and Asian modified CKD-EPI can be a satisfactory method and may be the most suitable creatinine-based equation.

Reassessment of kidney function equations in predicting long-term survival in cardiac surgery

BACKGROUND/OBJECTIVES

Chronic kidney disease (CKD) is a risk factor for long-term survival in cardiac surgery. The Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD) study, CKD Epidemiology Collaboration (CKD-EPI), revised Lund-Malmö (LM), and full age spectrum equations are used to estimate glomerular filtration rates (eGFR), but each have advantages and disadvantages. Our objective was to determine which equation better predicts long-term survival.

METHODS

Data on 1492 consecutive patients who underwent isolated off-pump coronary artery bypass surgery between September 1996 and December 2008 were prospectively collected. Preoperative and postoperative eGFR were calculated using the five equations and compared using Cox regression analyses and time-dependent receiver operating characteristic (ROC) curves at 10 years.

RESULTS

In a Cox regression model after correction for significant predictors of long-term mortality, adjusted hazard ratios (HR) for one standard deviation increase in preoperative eGFR were 0.661 (P < .0001), 0.844 (P = .0166), 0.787 (P = .0002), 0.746 (P < .0001), and 0.717 (P < .0001) for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively. The areas under the time-dependent ROC curve at 10 years also showed that the CG formula has a better predictive value. Postoperative eGFR at discharge were also significant predictors of long-term mortality (HR = 0.603, P < .0001; HR = 0.725, P < .0001; HR = 0.688, P < .0001; HR = 0.673, P < .0001; HR = 0.632, P < .0001 for the CG, MDRD, CKD-EPI, LM, and FAS equations, respectively).

CONCLUSIONS

The CG formula was shown to better predict survival in cardiac surgery, though the FAS equation has a comparable prognostic value. Additionally, postoperative eGFR at discharge also predicted long-term survival.

Revised Equations to Estimate Glomerular Filtration Rate from Serum Creatinine and Cystatin C in China

Aim: Our previous study demonstrated that the cystatin C-based chronic kidney disease (CKD)-EPI equation and combined by serum creatinine (CKD-EPIscr-cys) had better capability to accurately evaluate glomerular filtration rate in the CKD participants. Considering that the accuracy of estimated glomerular filtration rate (eGFR) remains less ideally, it is essential to modify the equation by including the Chinese eGFR racial factor in order to improve its performance. Methods: Two prospective cohorts were enrolled in 2 medical centers. New equations were developed in 529 participants and validated in 313 participants. Reference glomerular filtration rate (rGFR) was taken by 99mTc-DTPA renal dynamic imaging method (Gates method). The primary outcomes of this study were bias, precision (interquartile range of difference [IQR]), and accuracy (the proportion of eGFR within 30% of rGFR [P30] and root mean square error [RMSE]) of eGFR versus rGFR. Results: In a development data set, Chinese coefficients for CKD-EPIscr (C-CKD-EPIscr), CKD-EPIcys (C-CKD-EPIcys), and CKD-EPIscr-cys (C-CKD-EPIscr-cys) were 0.871, 0.879, and 0.891, respectively. In a validation data set, C-CKD-EPIcys was the most accurate with highest P30 value (62.3%), relative lowest IQR (15.45), and RMSE (0.80) among 6 equations, though the bias of C-CKD-EPIcys was not better than CKD-EPIcys. C-CKD-EPIscr and C-CKD-EPIscr-cys equations were improved in bias (p < 0.001), ­precision, and accuracy (p = 0.004 and <0.001 for P30) compared with CKD-EPIscr and CKD-EPIscr-cys. Conclusion: C-CKD-EPIcys was the most accurate with the highest P30 value, relative lowest IQR, and RMSE among 6 equations. C-CKD-EPIscr and C-CKD-EPIscr-cys equations were improved in bias, precision, and accuracy. Other external validation of these equations is needed.

A Validation Study on eGFR Equations in Chinese Patients With Diabetic or Non-diabetic CKD

Aims: It remains controversial to choose the optimal equation to estimate glomerular filtration rate (GFR) in chronic kidney disease (CKD) patients with diabetes. Materials and Methods: Two hundred and fifteen diabetic CKD patients and 192 non-diabetic CKD patients were enrolled in this study. Iohexol GFR, serum creatinine (SCr), and Cystatin C(CysC) were measured simultaneously for each patient. SCr- and CysC-based estimated GFR (eGFR) were calculated through eight equations, including three CKD-EPI equations, Revised Lund-Malmö study equation (RLM), CAPA equation, and three Full Age Spectrum (FAS) equations. Bias, precision, and accuracy were compared among eGFR equations with iohexol-GFR serving as measured GFR (mGFR). Independent predictive factors of accuracy were explored using multivariate logistic regression analysis. Results: In the diabetic group, CKD-EPI_SCr-CysC showed the best performance among three CKD-EPI equations (interquartile range of 13.88 ml/min/1.73 m² and 30% accuracy of 72.56%). Compared to CKD-EPI_SCr-CysC, the other five equations did not significantly improve the performance of GFR estimates. Mostly, eGFR equations were less accurate in diabetic group than in non-diabetic group. Significant differences were found in different mGFR range (P < 0.001). The multivariate logistic regression analysis identified that BMI, mGFR, and diabetic kidney disease (DKD) status were independent predictors of accuracy of three equations in diabetic group. HbA1c was a predictor of accuracy of CKD-EPI_SCr and CKD-EPI_CysC in diabetic group. Conclusions: This study showed that eGFR equations were less accurate in the diabetic group than in the non-diabetic group. CKD-EPI_Scr-CysC had the best performance among CKD-EPI equations in Chinese diabetic CKD patients. The other five equations did not significantly improve the performance of GFR estimates. BMI, mGFR, DKD status, and HbA1c were independent factors associated with accuracy in eGFR equations.