Article

Simple Cystatin C Formula Compared to Sophisticated CKD-EPI Formulas for Estimation of Glomerular Filtration Rate in the Elderly

Department of Nephrology, University Medical Center Maribor, Maribor, Slovenia.
Therapeutic apheresis and dialysis: official peer-reviewed journal of the International Society for Apheresis, the Japanese Society for Apheresis, the Japanese Society for Dialysis Therapy (Impact Factor: 1.71). 06/2011; 15(3):261-8. DOI: 10.1111/j.1744-9987.2011.00948.x
Source: PubMed

ABSTRACT

Despite the fact that the serum creatinine level is notoriously unreliable for the estimation of glomerular filtration rate (GFR) in the elderly, the serum creatinine concentration and serum creatinine-based formulas, such as the Modification of Diet in Renal Disease study equation (MDRD) are the most commonly used markers to estimate GFR. Recently, serum cystatin C-based formulas, the newer creatinine formula (the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI creatinine formula), and an equation that uses both serum creatinine and cystatin C (CKD-EPI creatinine and cystatin formula) were proposed as new GFR markers. The aim of our study was to compare the MDRD formula, CKD-EPI creatinine formula, CKD-EPI creatinine and cystatin formula, and simple cystatin C formula (100/serum cystatin C) against (51) Cr-EDTA clearance in the elderly. A total of 317 adult Caucasian patients aged >65 years were enrolled. In each patient, (51) Cr-EDTA clearance, serum creatinine, and serum cystatin C were determined, and the GFR was calculated using the MDRD formula, CKD-EPI formulas, and simple cystatin C formula. Statistically significant correlations between (51) Cr-EDTA clearance and all formulas were found. In the receiver operating characteristic (ROC) curve analysis with a cut-off of GFR 45 mL/min/1.73 m(2), a higher diagnostic accuracy was achieved with the equation that uses both serum creatinine and cystatin C (CKD-EPI creatinine and cystatin formula) than the MDRD formula (P < 0.013) or CKD-EPI creatinine formula (P < 0.01), but it was not higher than that achieved for the simple cystatin C formula (P = 0.335). Bland and Altman analysis for the same cut-off value showed that the creatinine formulas underestimated and the simple cystatin C formula overestimated measured GFR. All equations lacked precision. The accuracy within 30% of estimated (51) Cr-EDTA clearance values differ according to the stage of CKD. Analysis of the ability to correctly predict GFR below and above 45 mL/min/1.73 m(2) showed a high prediction for all formulas. Our results indicate that the simple cystatin C formula, which requires just one variable (serum cystatin C concentration), is a reliable marker of GFR in the elderly and comparable to the creatinine formulas, including the CKD-EPI formulas.

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Available from: Robert Ekart, Sep 30, 2014
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    • "It has been demonstrated that serum cystatin C possesses a number of characteristics that make it an ideal endogenous GFR marker (6). Previous studies have shown that serum cystatin C is superior to serum creatinine as a GFR marker in patients with a mild or moderate reduction in GFR (11–13). Meta-analyses have also demonstrated that serum cystatin C is superior to creatinine in measuring renal function (10,30). "
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    ABSTRACT: The aim of the present study was to explore the association between the cystatin C-based estimated glomerular filtration rate (eGFRcys) and the SYNTAX score (SXscore) in patients with diabetes. To the best of our knowledge, this correlation has not been reported previously. The eGFRcys and SXscore from 612 consecutive patients with diabetes were retrospectively included in this study. The patients were angiographically diagnosed with coronary artery disease (CAD) between July 2010 and March 2012 at the Department of Endocrinology. The SXscore was calculated using a previously described SXscore algorithm. Pearson correlations were used to analyze the correlation between eGFRcys and SXscore. Patients with renal dysfunction were older, more often female and more likely to have a history of hypertension when compared with those with normal renal function. The eGFRcys values were significantly lower and the cystatin C levels were significantly higher in the highest SXscore group than those in other groups (P<0.001). Correlation analysis indicated that eGFRcys was negatively correlated with the SXscore (r=-0.7918, P<0.001). In addition, a significantly positive correlation was identified between levels of cystatin C and the SXscore (r=0.8891, P<0.001). In conclusion, eGFRcys is an independent predictor of SXscore in patients with diabetes. The eGFRcys-estimating method may be considered important in the assessment of the SXscore in patients with diabetes.
    Full-text · Article · Apr 2014 · Experimental and therapeutic medicine
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    • "However, previous research indicated that use of fewer variables can yield acceptable estimates of GFR. For example, Bevc et al. [28] reported that a cystatin C-based estimate, which only requires measurement of serum cystatin C, is a reliable marker of GFR in elderly patients and is comparable to the creatinine-based formulae, including the CKD-EPI formulae. Our results suggest that an RBF model based on a single measurement (SCr) can provide precise and accurate estimates of GFR. "
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    ABSTRACT: Accurate and precise estimates of glomerular filtration rate (GFR) are essential for clinical assessments, and many methods of estimation are available. We developed a radial basis function (RBF) network and assessed the performance of this method in the estimation of the GFRs of 207 patients with type-2 diabetes and CKD. Standard GFR (sGFR) was determined by 99mTc-DTPA renal dynamic imaging and GFR was also estimated by the 6-variable MDRD equation and the 4-variable MDRD equation. Bland-Altmann analysis indicated that estimates from the RBF network were more precise than those from the other two methods for some groups of patients. However, the median difference of RBF network estimates from sGFR was greater than those from the other two estimates, indicating greater bias. For patients with stage I/II CKD, the median absolute difference of the RBF network estimate from sGFR was significantly lower, and the P50 of the RBF network estimate (n = 56, 87.5%) was significantly higher than that of the MDRD-4 estimate (n = 49, 76.6%) (p < 0.0167), indicating that the RBF network estimate provided greater accuracy for these patients. In patients with type-2 diabetes mellitus, estimation of GFR by our RBF network provided better precision and accuracy for some groups of patients than the estimation by the traditional MDRD equations. However, the RBF network estimates of GFR tended to have greater bias and higher than those indicated by sGFR determined by 99mTc-DTPA renal dynamic imaging.
    Full-text · Article · Aug 2013 · BMC Nephrology
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    • "Application of SC-based GFR prediction equations to elderly patients with CKD is limited. Bevc et al26 found that both the MDRD equations and the CKD-EPI equation lacked precision, and the accuracy within 30% of estimated 51Cr EDTA clearance values differs according to the stage of CKD. Burkhardt et al27 demonstrated that the accuracies and precisions of the CG equation and the MDRD equations were low, and that there was an underestimation of actual GFR. "
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    ABSTRACT: Chronic kidney disease (CKD) is recognized worldwide as a public health problem, and its prevalence increases as the population ages. However, the applicability of formulas for estimating the glomerular filtration rate (GFR) based on serum creatinine (SC) levels in elderly Chinese patients with CKD is limited. Based on values obtained with the technetium-99m diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) renal dynamic imaging method, 319 elderly Chinese patients with CKD were enrolled in this study. Serum creatinine was determined by the enzymatic method. The GFR was estimated using the Cockroft-Gault (CG) equation, the Modification of Diet in Renal Disease (MDRD) equations, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, the Jelliffe-1973 equation, and the Hull equation. The median of difference ranged from -0.3-4.3 mL/min/1.73 m(2). The interquartile range (IQR) of differences ranged from 13.9-17.6 mL/min/1.73 m(2). Accuracy with a deviation less than 15% ranged from 27.6%-32.9%. Accuracy with a deviation less than 30% ranged from 53.6%-57.7%. Accuracy with a deviation less than 50% ranged from 74.9%-81.5%. None of the equations had accuracy up to the 70% level with a deviation less than 30% from the standard glomerular filtration rate (sGFR). Bland-Altman analysis demonstrated that the mean difference ranged from -3.0-2.4 mL/min/1.73 m(2). However, the agreement limits of all the equations, except the CG equation, exceeded the prior acceptable tolerances defined as 60 mL/min/1.73 m(2). When the overall performance and accuracy were compared in different stages of CKD, GFR estimated using the CG equation showed promising results. Our study indicated that none of these equations were suitable for estimating GFR in the elderly Chinese population investigated. At present, based on overall performance, as well as performance in different CKD stages, the CG equation may be the most accurate for estimating GFR in elderly Chinese patients with CKD.
    Full-text · Article · Oct 2012 · Clinical Interventions in Aging
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