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

2019 ◽  
Vol 44 (4) ◽  
pp. 553-564 ◽  
Author(s):  
Min Yang ◽  
Yonghua Zou ◽  
Tong Lu ◽  
Yule Nan ◽  
Jianying Niu ◽  
...  

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.

Author(s):  
Julie Mouron-Hryciuk ◽  
François Cachat ◽  
Paloma Parvex ◽  
Thomas Perneger ◽  
Hassib Chehade

AbstractGlomerular filtration rate (GFR) is difficult to measure, and estimating formulas are notorious for lacking precision. This study aims to assess if the inclusion of additional biomarkers improves the performance of eGFR formulas. A hundred and sixteen children with renal diseases were enrolled. Data for age, weight, height, inulin clearance (iGFR), serum creatinine, cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), parathyroid hormone (PTH), albumin, and brain natriuretic peptide (BNP) were collected. These variables were added to the revised and combined (serum creatinine and cystatin C) Schwartz formulas, and the quadratic and combined quadratic formulas. We calculated the adjusted r-square (r2) in relation to iGFR and tested the improvement in variance explained by means of the likelihood ratio test. The combined Schwartz and the combined quadratic formulas yielded best results with an r2 of 0.676 and 0.730, respectively. The addition of BNP and PTH to the combined Schwartz and quadratic formulas improved the variance slightly. NGAL and albumin failed to improve the prediction of GFR further. These study results also confirm that the addition of cystatin C improves the performance of estimating GFR formulas, in particular the Schwartz formula.Conclusion: The addition of serum NGAL, BNP, PTH, and albumin to the combined Schwartz and quadratic formulas for estimating GFR did not improve GFR prediction in our population. What is Known:• Estimating glomerular filtration rate (GFR) formulas include serum creatinine and/or cystatin C but lack precision when compared to measured GFR.• The serum concentrations of some biological parameters such as neutrophil gelatinase-associated lipocalin (NGAL), parathyroid hormone (PTH), albumin, and brain natriuretic peptide (BNP) vary with the level of renal function. What is New:• The addition of BNP and PTH to the combined quadratic formula improved its performance only slightly. NGAL and albumin failed to improve the prediction of GFR further.


2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Magdalena Szopa ◽  
Maria Kapusta ◽  
Bartlomiej Matejko ◽  
Tomasz Klupa ◽  
Teresa Koblik ◽  
...  

Introduction. We previously showed that in HNF1A-MODY the cystatin C-based glomerular filtration rate (GFR) estimate is higher than the creatinine-based estimate. Currently, we aimed to replicate this finding and verify its clinical significance. Methods. The study included 72 patients with HNF1A-MODY, 72 with GCK-MODY, 53 with type 1 diabetes (T1DM), 70 with type 2 diabetes (T2DM), and 65 controls. Serum creatinine and cystatin C levels were measured. GFR was calculated from creatinine and cystatin C using the CKD-EPI creatinine equation (eGRF-cr) and CKD-EPI cystatin C equation (eGFR-cys), respectively. Results. Cystatin C levels were lower (p<0.001) in the control (0.70±0.13 mg/L), HNF1A (0.75±0.21), and GCK (0.72±0.16 mg/L) groups in comparison to those with either T1DM (0.87±0.15 mg/L) or T2DM (0.9±0.23 mg/L). Moreover, eGFR-cys was higher than eGRF-cr in HNF1A-MODY, GCK-MODY, and the controls (p=0.004; p=0.003; p<0.0001). This corresponded to 8.9 mL/min/1.73 m2, 9.7 mL/min/1.73 m2, and 16.9 mL/min/1.73 m2 of difference. Additionally, T1DM patients had higher eGFR-cr than eGFR-cys (11.6 mL/min/1.73 m2; p=0.0004); no difference occurred in T2DM (p=0.91). Conclusions. We confirmed that eGFR-cys values in HNF1A-MODY patients are higher compared to eGFR-cr. Some other differences were also described in diabetic groups. However, none of them appears to be clinically relevant.


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