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    Comparing GFR Estimating Equations Using Cystatin C and Creatinine in Elderly Individuals. Fan Li,Levey Andrew S,Gudnason Vilmundur,Eiriksdottir Gudny,Andresdottir Margret B,Gudmundsdottir Hrefna,Indridason Olafur S,Palsson Runolfur,Mitchell Gary,Inker Lesley A Journal of the American Society of Nephrology : JASN Current guidelines recommend reporting eGFR using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations unless other equations are more accurate, and recommend the combination of creatinine and cystatin C (eGFRcr-cys) as more accurate than either eGFRcr or eGFRcys alone. However, preferred equations and filtration markers in elderly individuals are debated. In 805 adults enrolled in the community-based Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study, we measured GFR (mGFR) using plasma clearance of iohexol, standardized creatinine and cystatin C, and eGFR using the CKD-EPI, Japanese, Berlin Initiative Study (BIS), and Caucasian and Asian pediatric and adult subjects (CAPA) equations. We evaluated equation performance using bias, precision, and two measures of accuracy. We first compared the Japanese, BIS, and CAPA equations with the CKD-EPI equations to determine the preferred equations, and then compared eGFRcr and eGFRcys with eGFRcr-cys using the preferred equations. Mean (SD) age was 80.3 (4.0) years. Median (25th, 75th) mGFR was 64 (52, 73) ml/min per 1.73 m(2), and the prevalence of decreased GFR was 39% (95% confidence interval, 35.8 to 42.5). Among 24 comparisons with the other equations, CKD-EPI equations performed better in 9, similar in 13, and worse in 2. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr in four metrics, better than eGFRcys in two metrics, and similar to eGFRcys in two metrics. In conclusion, neither the Japanese, BIS, nor CAPA equations were superior to the CKD-EPI equations in this cohort of community-dwelling elderly individuals. Using the CKD-EPI equations, eGFRcr-cys performed better than eGFRcr or eGFRcys. 10.1681/ASN.2014060607
    Performance of creatinine-based equations for estimating glomerular filtration rate changes over time. van Rijn Marieke H C,Metzger Marie,Flamant Martin,Houillier Pascal,Haymann Jean-Philippe,van den Brand Jan A J G,Froissart Marc,Stengel Benedicte Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association BACKGROUND:Glomerular filtration rate (GFR) is commonly used to monitor chronic kidney disease (CKD) progression, but its validity for evaluating kidney function changes over time has not been comprehensively evaluated. We assessed the performance of creatinine-based equations for estimating GFR slope according to patient characteristics and specific CKD diagnosis. METHODS:In the NephroTest cohort study, we measured GFR 5324 times by chromium 51-labeled ethylenediamine tetraacetic acid renal clearance in 1955 adult patients with CKD Stages 1-4 referred to nephrologists (Stages 1-2, 19%) and simultaneously estimated GFR with both the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) equations for isotope dilution mass spectrometry traceable creatinine; absolute and relative GFR slopes were calculated using a linear mixed model. RESULTS:Over a median follow-up of 3.4 [interquartile range (IQR) 2.0-5.6] years, the decline in mean absolute and relative measured GFR (mGFR) and CKD-EPI and MDRD estimated GFR (eGFR) was 1.6 ± 1.2, 1.5 ± 1.4 and 1.3 ± 1.3 mL/min/1.73 m2/year and 5.9 ± 5.3, 5.3 ± 5.3 and 4.8 ± 5.2%/year, respectively; 52% and 55% of the patients had MDRD and CKD-EPI eGFR slopes within 30% of mGFR slopes. Both equations tended to overestimate the GFR slope in the youngest patients and underestimate it in the oldest, thus producing inverse associations between age and mGFR versus eGFR slope. Other patient characteristics and specific CKD diagnoses had little effect on the performance of the equations in estimating associations. CONCLUSIONS:This study shows little bias, but poor precision in GFR slope estimation for both MDRD and CKD-EPI equations. Importantly, bias strongly varied with age, possibly due to variations in muscle mass over time, with implications for clinical care and research. 10.1093/ndt/gfy278
    Estimating glomerular filtration rate: Performance of the CKD-EPI equation over time in patients with type 2 diabetes. Wood Anna J,Churilov Leonid,Perera Nayomi,Thomas David,Poon Aurora,MacIsaac Richard J,Jerums George,Ekinci Elif I Journal of diabetes and its complications AIMS:To assess the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation at baseline and longitudinally in people with type 2 diabetes. METHODS:Adults with type 2 diabetes attending Austin Health, Melbourne, with≥3 prospective GFR measurements were included in this retrospective study. Plasma disappearance rate of DTPA (diethylene-triamine-penta-acetic acid) was used to calculate measured GFR (mGFR) and compared to estimated GFR (eGFR). The agreement between mGFR and eGFR was estimated using Intraclass Correlation Coefficient (ICC). RESULTS:152 patients had a median of 4 (IQR: 3, 5) mGFR measurements over a period of 11years (IQR: 9, 12). The difference between mGFR and eGFR increased proportionally to the magnitude of the GFR, increasing by 0.2ml/min/1.73m(2) for every 1ml/min/1.73m(2) increase in mGFR, indicative of proportional bias. At lower mGFR levels, eGFR overestimated mGFR, and at higher mGFR levels, eGFR underestimated mGFR. There was a significant association between LDL cholesterol, triglycerides, HbA1c, diastolic blood pressure and the difference between mGFR and eGFR. CONCLUSIONS:The CKD-EPI formula underestimates mGFR and the rate of decline of mGFR in patients with type 2 diabetes with an mGFR greater than 60ml/min/1.73m(2). The association between LDL cholesterol, triglycerides, HbA1c, diastolic blood pressure and the difference between mGFR and eGFR warrants further study. 10.1016/j.jdiacomp.2015.08.025
    Improved glomerular filtration rate estimation using new equations combined with standardized cystatin C and creatinine in Chinese adult chronic kidney disease patients. Guo Xiuzhi,Qin Yan,Zheng Ke,Gong Mengchun,Wu Jie,Shou Weiling,Cheng Xinqi,Xia Liangyu,Xu Ermu,Li Xuemei,Qiu Ling Clinical biochemistry OBJECTIVES:The newly developed glomerular filtration rate (GFR)-estimating equations developed by the CKD-EPI Collaboration and Feng et al. (2013) that are based on standardized serum cystatin C (ScysC), combined/not combined with serum creatinine (Scr), require further validation in China. We compared the performance of four new equations (CKD-EPIcys, CKD-EPIcr-cys, Fengcys, and Fengcr-cys equations) with the CKD-EPI creatinine equation (CKD-EPIcr) in adult Chinese chronic kidney disease (CKD) patients to clarify their clinical application. DESIGN AND METHODS:GFR was measured using the dual plasma sampling (99m)Tc-DTPA method (mGFR) in 252 adult CKD patients enrolled from four centres. Scr and ScysC were measured by standardized assays in a central laboratory. Each equation's performance was assessed using bias, precision, accuracy, agreement, and correct classification of the CKD stage. RESULTS:The measured GFR was 46 [25-83] mL/min per 1.73 m(2). The CKD-EPIcys, CKD-EPIcr-cys and Fengcys equations provided significantly higher accuracy (P15: 38.9%, 39.7%, and 38.9%) than the CKD-EPIcr equation (29.8%). The CKD-EPIcr-cys and Fengcr-cys equations presented higher precision (IQR of the difference, 16.4 and 17.3 mL/min per 1.73 m(2), respectively) and narrower acceptable limits in Bland-Altman analysis (56.6 and 50.8 mL/min per 1.73 m(2), respectively) than single marker-based equations. The CKD-EPIcr-cys equation achieved the highest overall correct proportion (61.5%) in classification of CKD stages. CONCLUSIONS:Combining ScysC and Scr measurements for GFR estimation improves diagnostic performance. The Scr-ScysC equation showed better performance than equations based on either marker alone. The CKD-EPIcr-cys equation showed the best performance for GFR estimation in Chinese adult CKD patients. 10.1016/j.clinbiochem.2014.05.060
    Development and validation of a more accurate estimating equation for glomerular filtration rate in a Chinese population. Li Dai-Yang,Yin Wen-Jun,Yi Yi-Hu,Zhang Bi-Kui,Zhao Jun,Zhu Chao-Nan,Ma Rong-Rong,Zhou Ling-Yun,Xie Yue-Liang,Wang Jiang-Lin,Zuo Shan-Ru,Liu Kun,Hu Can,Zhou Ge,Zuo Xiao-Cong Kidney international Previously published equations to estimate glomerular filtration rate (GFR) have limited accuracy in Asian populations. We aimed to develop and validate a more accurate equation for estimated GFR (eGFR) in the Chinese population, using data from 8571 adults who were referred for direct measurement of GFR by renal dynamic imaging (mGFR) at 3 representative hospitals in China. Patients from the Third Xiangya Hospital were included in our development (n=1730) and internal validation sets (n=1042) and patients from the other hospitals comprised the external validation set (n=5799). We excluded patients who were prescribed medications known to influence the tubular secretion of creatinine, patients on dialysis, kidney transplant recipients, and patients with missing creatinine values or with creatinine >700 μmol/l. We derived a novel eGFR equation by linear regression analysis and compared the performance to 12 creatinine-based eGFR equations, including previously published equations for use in Chinese or Asian populations. In the development and internal validation sets, the novel Xiangya equation had high accuracy (accuracy within 30% [P30], 79.21% and 84.33%, respectively), low bias (mean difference between mGFR and eGFR, -1.97 and -1.85 ml/min per 1.73 m, respectively), and high precision (interquartile range of the differences, 21.13 and 18.88 ml/min per 1.73 m, respectively). In external validation, the Xiangya equation had the highest P30 among all eGFR equations, with P30 ≤ 75% for the other 12 equations. This novel equation provides more accurate GFR estimates in Chinese adults and could replace existing eGFR equations for use in the Chinese population. 10.1016/j.kint.2018.10.019
    Comparison of creatinine and cystatin formulae with Chromium-ethylenediaminetetraacetic acid glomerular filtration rate in patients with decompensated cirrhosis. Cholongitas Evangelos,Ioannidou Maria,Goulis Ioannis,Chalevas Parthenis,Ntogramatzi Fani,Athanasiadou Zoi,Notopoulos Athanasios,Alevroudis Manolis,Sinakos Emmanouil,Akriviadis Evangelos Journal of gastroenterology and hepatology BACKGROUND AND AIM:Evaluation of renal function, that is, glomerular filtration rate (GFR), has become very important, but conventional mathematical formulae for GFR assessment are inaccurate in patients with cirrhosis. The aim of the present study was to compare serum creatinine (sCr)-based and serum cystatin C (cysC)-based estimated GFR (eGFR) formulae with Chromium-ethylenediaminetetraacetic acid GFR ( Chr-GFR) in patients with stable decompensated cirrhosis. METHODS:In 129 Caucasian patients with decompensated cirrhosis, we assessed sCr-based GFRs [Modification of Diet in Renal Disease and chronic kidney disease-epidemiology (CKD-EPI)-sCr formulae], cysC-based GFRs [Hoek, Larsson, and CKD-EPI-cysC equations], and the mathematical formulae, which combined both sCr and cysC [i.e. CKD-EPI-sCr-cysC and the specific for cirrhotics formula recently proposed by Mindikoglu et al. (Mindikoglu-eGFR)]. Multivariate linear regression analysis was used for GFR predictors in our cohort. RESULTS:The correlations between Chr-GFR and all mathematical formulae were good (Spearman r  > 0.68, P < 0.001). Modification of Diet in Renal Disease and CKD-EPI-sCr had lower bias (6.6 and -4.8, respectively), compared with the other eGFRs, while Mindikoglu-eGFR and CKD-EPI-sCr-cysC formulae had greater precision (17.1 and 17.3, respectively), compared with the other eGFRs. CKD-EPI-sCr and Mindikoglu-eGFR had higher accuracy (39% and 41%, respectively), compared with the other eGFRs. The factors independently associated with the Chr-GFR were age, cysC, and sCr, and the new derived formula had lower bias (0.89) and similar precision (17.2) and accuracy (41%) with Mindikoglu-eGFR formula. CONCLUSION:The specific mathematical formulae derived from patients with cirrhosis seem to provide superior assessment of renal function, compared with the conventional used sCr-based and cysC-based formulae. 10.1111/jgh.13446
    Comparison of Performance of Improved Serum Estimators of Glomerular Filtration Rate (GFR) to Tc-DTPA GFR Methods in Patients with Hepatic Cirrhosis. Haddadin Zaid,Lee Vivian,Conlin Christopher,Zhang Lei,Carlston Kristi,Morrell Glen,Kim Daniel,Hoffman John M,Morton Kathryn Journal of nuclear medicine technology Glomerular filtration rate (GFR) measurements are critical in patients with hepatic cirrhosis but potentially erroneous when based on serum creatinine. New equations for estimated GFR (eGFR) have shown variable performance in cirrhotics, possibly because of inaccuracies in reference methods for measured GFR (mGFR). The primary objective was to compare the performance of 4 improved eGFR equations with a 1-compartment, 2-sample plasma slope intercept Tc-DTPA mGFR method to determine whether any of the eGFR calculations could replace plasma Tc-DTPA mGFR in patients with cirrhosis. The secondary objective was to test the hypothesis that mGFR using voluntary voided urine collections introduces error compared with plasma-only methods. Fifty-four patients with hepatic cirrhosis underwent mGFR determinations from 2 plasma samples at 1 and 3 h after intravenous administration of 185 MBq of Tc-DTPA. GFR was also generated by a UV/P calculation derived from blood and urine samples. These mGFRs were compared with the eGFRs generated by 4 estimating equations: MDRD (Modified Diet in Renal Disease), CKD-EPI (Chronic Kidney Disease-Epidemiology Collaboration) (serum creatinine [SCr]), CKD-EPI (cystatin [CysC]), and CKD-EPI (CysC+SCr). eGFRs were compared with mGFRs by Pearson correlation, precision, bias, percentage bias, and accuracy (eGFRs varying by <10% [p10], <20% [p20] or <30% [p30] from the corresponding mGFR). All eGFRs showed poorer performance when the UV/P Tc-DTPA mGFR was used as the reference than when the plasma Tc-DTPA mGFR was used. When compared with the plasma Tc-DTPA mGFR method, the performance of all eGFR equations was superior to most published reports. There was a moderately good positive correlation between eGFRs and mGFRs. When compared with plasma Tc-DTPA mGFR, precision of eGFRs was in the range of 14-20 mL/min and showed a negligible bias. Compared with the plasma Tc-DTPA mGFR, CKD-EPI (CysC+SCr) showed the best overall performance and accuracy, at 85.19% (p30), 75.93% (p20), and 42.59% (p10). Estimating equations for measuring eGFR performed better than in most published reports, attributable to use of the plasma Tc-DTPA mGFR method as a reference. CKD-EPI (CysC+SCr) eGFR showed the best overall performance. However, more discriminating methods may be required when accurate GFR measurements are necessary. mGFR measurements using urine collections may introduce error compared with plasma-only methods. 10.2967/jnmt.116.180851
    Performance of the Cockcroft-Gault, MDRD, and new CKD-EPI formulas in relation to GFR, age, and body size. Michels Wieneke Marleen,Grootendorst Diana Carina,Verduijn Marion,Elliott Elise Grace,Dekker Friedo Wilhelm,Krediet Raymond Theodorus Clinical journal of the American Society of Nephrology : CJASN BACKGROUND AND OBJECTIVES:We compared the estimations of Cockcroft-Gault, Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations to a gold standard GFR measurement using (125)I-iothalamate, within strata of GFR, gender, age, body weight, and body mass index (BMI). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS:For people who previously underwent a GFR measurement, bias, precision, and accuracies between measured and estimated kidney functions were calculated within strata of the variables. The relation between the absolute bias and the variables was tested with linear regression analysis. RESULTS:Overall (n = 271, 44% male, mean measured GFR 72.6 ml/min per 1.73 m(2) [SD 30.4 ml/min per 1.73 m(2)]), mean bias was smallest for MDRD (P < 0.01). CKD-EPI had highest accuracy (P < 0.01 compared with Cockcroft-Gault), which did not differ from MDRD (P = 0.14). The absolute bias of all formulas was related to age. For MDRD and CKD-EPI, absolute bias was also related to the GFR; for Cockcroft-Gault, it was related to body weight and BMI as well. In all extreme subgroups, MDRD and CKD-EPI provided highest accuracies. CONCLUSIONS:The absolute bias of all formulas is influenced by age; CKD-EPI and MDRD are also influenced by GFR. Cockcroft-Gault is additionally influenced by body weight and BMI. In general, CKD-EPI gives the best estimation of GFR, although its accuracy is close to that of the MDRD. 10.2215/CJN.06870909
    Estimation of renal function in subjects with normal serum creatinine levels: influence of age and body mass index. Verhave Jacobien C,Fesler Pierre,Ribstein Jean,du Cailar Guilhem,Mimran Albert American journal of kidney diseases : the official journal of the National Kidney Foundation BACKGROUND:The Cockcroft-Gault (CG) and simplified Modification of Diet in Renal Disease (MDRD) formulas are the most widely used estimates of renal function. The influence of age and body mass index (BMI) on the performance of these equations was analyzed in 850 subjects with serum creatinine levels less than 1.5 mg/dL (<133 micromol/L). METHODS:Glomerular filtration rate (GFR) was measured as urinary clearance of continuously infused technetium Tc 99m-labeled diethylene triaminopentaacetic acid. Performance was assessed as bias, precision, and accuracy. RESULTS:In the total population, the CG and MDRD calculations based on enzymatic measurement of serum creatinine (which is constantly less than that obtained by using the alkaline picrate [Jaffé] method) significantly underestimated GFR by 4.9 and 12.4 mL/min/1.73 m2 (0.08 and 0.21 mL/s/1.73 m2), respectively. In patients 65 years and older, underestimation by means of the CG formula was enhanced, whereas that by means of the MDRD formula was blunted, compared with the group younger than 65 years (-11.3 versus -3.7 mL/min/1.73 m2 [-0.19 versus -0.06 mL/s/1.73 m2] for CG and -3.7 versus -14.0 mL/min/1.73 m2 [-0.06 versus -0.23 mL/s/1.73 m2] for MDRD). GFR was underestimated to a large extent by means of the MDRD equation irrespective of BMI. Conversely, the underestimation by means of the CG formula found in lean people (-13.0 mL/min/1.73 m2 [-0.22 mL/s/1.73 m2]) was blunted in overweight people (BMI, 25 to 30 kg/m2) and reversed to overestimation (+10.1 mL/min/1.73 m2 [+0.17 mL/s/1.73 m2]) in obese subjects (BMI > 30 kg/m2). CONCLUSION:As suggested by estimations obtained using enzymatic serum creatinine measurement, the MDRD equation may be the estimation of choice in elderly patients, whereas the CG estimate is preferable in subjects younger than 65 years. Nevertheless, when obesity is present, no reliable estimation can be obtained by using the CG or MDRD formula. 10.1053/j.ajkd.2005.05.011
    Comparison of creatinine clearance estimates in subgroups based on Body Mass Index and albumin. Grapsa Eirini,Pipili Chrysoula,Angelopoulos Epameinondas,Pantelias Kostantinos,Kapetanaki Antigoni,Deda Edmond,Kiousi Eva,Tzanatos Helen Minerva urologica e nefrologica = The Italian journal of urology and nephrology BACKGROUND:The establishment of accurate equations for glomerular filtration rate (GFR) estimations is still far from the realization. Factors such as age, diabetes, stage of CKD, pregnancy, muscle mass and ethic nation are associated with less reliance upon commonly utilized estimation equations. We aimed to compare the routine use of 24-hour creatinine clearance (CrCl) and GFR estimates calculated by Crockoft-Gault (CG) and modification of diet in renal disease (MDRD) formulas in patients with different levels of renal dysfunction in subgroups, based on Body Mass Index (BMI) and serum albumin (Alb) levels. METHODS:Two hundred and seventy-nine non diabetic patients (172 men and 107 women), aged 54±23 years, with BMI 27.3±4.4 were enrolled in the study. All patients presented creatinine 1.8±1.2 (mg/dL) and Alb 3.5±1.3g/dL. The comparison of CrCl versus CG had bias 3.1 while the comparison of CrCl versus MDRD had a bias of 6.6. RESULTS:Univariate analysis showed that age, sex and BMI were not significant biases related to the CG, MDRD and CrCl. Indeed, the bias related to the CG was significantly lower than that related to MDRD in patients with either low or high serum albumin. Interestingly, the bias associated with CG was 1.3 in non-diabetic patients with Alb ≤3.5 mg /dL suggesting that CG equation could be used interchangeable to CrCl in these patients. CONCLUSION:CG gave a better prediction of measured CrCl than MDRD in Mediterranean, non-diabetic, non-hospitalized patients although misclassification of patients with regard to renal impairment stage was not present.
    Differential estimation of CKD using creatinine- versus cystatin C-based estimating equations by category of body mass index. Vupputuri Suma,Fox Caroline S,Coresh Josef,Woodward Mark,Muntner Paul American journal of kidney diseases : the official journal of the National Kidney Foundation BACKGROUND:Adiposity is associated with cystatin C. Cystatin C-based glomerular filtration rate (GFR) equations may result in overestimation of chronic kidney disease (CKD) prevalence at greater body mass index (BMI) levels. STUDY DESIGN:Cross-sectional. SETTING & PARTICIPANTS:6,709 US adult Third National Health and Nutrition Examination Survey participants. FACTOR:BMI. OUTCOME:Absolute percentage of difference in prevalence of stage 3 or 4 CKD between creatinine- and cystatin C-based estimating equations by level of BMI. MEASUREMENTS:Normal weight, overweight, and obesity were defined as BMI of 18.5 to less than 25.0, 25 to less than 30.0, and 30 kg/m(2) or greater, respectively. Stage 3 or 4 CKD (estimated glomerular filtration rate [eGFR], 15 to 59 mL/min/1.73 m(2)) was defined using the 4-variable creatinine-based Modification of Diet in Renal Disease Study equation (eGFR(MDRD)); cystatin C level, age, sex, and race equation (eGFR(CysC,age,sex,race)); cystatin C-only equation (eGFR(CysC)); cystatin C level of 1.12 mg/L or greater (increased cystatin C); and an equation incorporating serum creatinine level, cystatin C level, age, sex, and race (eGFR(Cr,CysC,age,sex,race)). RESULTS:Differences in stage 3 or 4 CKD prevalence estimates between eGFR(CysC,age,sex,race), eGFR(CysC), and increased cystatin C, separately, and eGFR(MDRD) were greater at higher BMI levels. Specifically, compared with estimates derived using eGFR(MDRD) for normal-weight, overweight, and obese participants, estimated prevalences of stage 3 or 4 CKD were 2.1%, 3.0%, and 6.5% greater when estimated by using eGFR(CysC,age,sex,race) (P trend = 0.005); 0.1%, 0.6%, and 2.2% greater for eGFR(CysC) (P trend = 0.03); 2.9%, 5.2%, and 9.5% greater for increased cystatin C (P trend < 0.001); and -0.1%, -0.4%, and 0.0% greater for eGFR(Cr,CysC,age,sex,race), respectively (P trend = 0.7). LIMITATIONS:No gold-standard measure of GFR was available. CONCLUSIONS:BMI may influence the estimated prevalence of stage 3 or 4 CKD when cystatin C-based equations are used. 10.1053/j.ajkd.2008.12.043
    Evaluation of glomerular filtration rate estimation by Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae in oncology patients. Ainsworth N L,Marshall A,Hatcher H,Whitehead L,Whitfield G A,Earl H M Annals of oncology : official journal of the European Society for Medical Oncology BACKGROUND:The aim was to evaluate the accuracy of Cockcroft-Gault, Jelliffe, Wright and Modification of Diet in Renal Disease (MDRD) formulae as a substitute for the gold standard measure of glomerular filtration rate (GFR) using chromium 51 EDTA. PATIENTS AND METHODS:Retrospective analysis of GFR measurements in oncology patients from a University Teaching Hospital over 3 years was carried out. Bias and precision of estimates of GFR were compared with measured GFR. RESULTS:Six hundred and sixty patients with measured GFR (median 90 ml/min, range 23-179 ml/min) were identified. Cockcroft-Gault produced the smallest bias (median percentage error -1.4%) and highest precision (median absolute percentage error 14.0%) and was the most accurate for carboplatin dosing. For patients>30% over their ideal body weight (IBW), using IBW+30% in the Cockcroft-Gault formula was more precise than using actual body weight or IBW. The Wright formula was most accurate for patients aged 70+years and patients with a body mass index (BMI)≥30 but overestimated GFR when GFR<50 ml/min. CONCLUSIONS:When measured GFR is unavailable, we advise estimating GFR using the Cockcroft-Gault formula and using IBW+30% for patients weighing>30% over their IBW. If the GFR is ≥50 ml/min and the patient is >70 years and/or BMI≥30, the Wright formula gives the best estimate of GFR. 10.1093/annonc/mdr539
    Cystatin C-Creatinine Based Glomerular Filtration Rate Equation in Obese Chronic Kidney Disease Patients: Impact of Deindexation and Gender. Lemoine Sandrine,Panaye Marine,Pelletier Caroline,Bon Chantal,Juillard Laurent,Dubourg Laurence,Guebre-Egziabher Fitsum American journal of nephrology BACKGROUND:Cystatin C is considered an alternative to creatinine to estimate glomerular filtration rate (GFR). However, studies have reported that increased adiposity is associated with a higher level of circulating cystatin C questioning the performance of estimation of GFR using cystatin C in obese subjects. METHODS:We prospectively included 166 obese stages 1-5 chronic kidney disease (CKD) patients between 2013 and 2015. GFR was measured with a reference method without (measured GFR [mGFR]) and with adjustment to body surface area (mGFRr) and estimated (eGFR) or de-indexed eGFR using the Chronic Kidney Disease and Epidemiology (CKD-EPI) equation using creatinine (CKD-EPIcreat), cystatin (CKD-EPIcyst) and the combination of cystatin and creatinine (CKD-EPIcyst-creat). RESULTS:The biases between mGFR and de-indexed CKD-EPIcyst-creat were significantly lower than de-indexed CKD-EPIcreat (p = 0.001). Accuracies were significantly better with de-indexed CKD-EPIcyst-creat compared to CKD-EPIcreat and CKD-EPIcyst, respectively (p = 0.04 and 0.03). Bland and Altman plot showed a great dispersion of all formulae when patients had a GFR >60 ml/min. Interestingly, there is a gender difference; biases, precisions and accuracies of de-indexed CKD-EPIcyst-creat were significantly lower in obese women. These results may be related to a difference in the change of body composition during obesity in men versus women and in fact only waist circumference (WC) was positively and significantly correlated with cystatin C (p < 0.0001) whereas body mass index (BMI; p = 0.3) was not; bias for CKD-EPIcyst-creat was related with WC. CONCLUSION:Cystatin C-creatinine-based GFR equations outperform creatinine-based formula in obese CKD patients especially those with BMI ≥35 and in obese women. 10.1159/000447365
    Modification of Diet in Renal Disease versus Chronic Kidney Disease Epidemiology Collaboration equation to estimate glomerular filtration rate in obese patients. Bouquegneau Antoine,Vidal-Petiot Emmanuelle,Vrtovsnik François,Cavalier Etienne,Rorive Marcelle,Krzesinski Jean-Marie,Delanaye Pierre,Flamant Martin Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association BACKGROUND:Obesity is a recognized risk factor for both the development and progression of chronic kidney disease (CKD). Accurate estimation of glomerular filtration rate (GFR) is thus important in these patients. We tested the performances of two creatinine-based GFR estimates, the Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, in an obese population. METHODS:Patients with body mass index (BMI) > 30 kg/m(2) were included. The reference method for measured GFR (mGFR) was (51)Cr-EDTA (single-injection method, two blood samples at 120 and 240 min). Both indexed and non-indexed results were considered. Serum creatinine was measured using the IDMS-traceable compensated Jaffe method. Mean bias (eGFR-mGFR), precision (SD around the bias) and accuracy within 30% (percentage of estimations within 30% of mGFR) were calculated for both equations. RESULTS:The population included 366 patients (185 women) from two different areas. Mean age was 55 ± 14 years, and mean BMI was 36 ± 7 kg/m(2). Mean mGFR was 56 ± 26 mL/min/1.73 m(2) (71 ± 35 mL/min without indexation). In the total population, mean bias was +1.9 ± 14.3 and +4.6 ± 14.7 mL/min/1.73 m(2) (P < 0.05), and accuracy 30% was 80 and 76% for the MDRD and CKD-EPI equations (P < 0.05), respectively. In patients with mGFR > 60 mL/min/1.73 m(2), mean bias was +4.6 ± 18.4 and +9.3 ± 17.2 mL/min/1.73 m(2) (P < 0.05), and accuracy 30% was 81 and 79% (NS) for the MDRD and CKD-EPI equations, respectively. CONCLUSIONS:The CKD-EPI equation did not outperform the MDRD study equation in this population of obese patients. 10.1093/ndt/gft329
    Glomerular filtration rate in patients with obstructive sleep apnea: the influence of cystatin-C-based estimations and comorbidity. Nowiński Adam,Czyżak-Gradkowska Anna,Jonczak Luiza,Korzybski Damian,Peradzyńska Joanna,Pływaczewski Robert,Śliwiński Paweł Journal of thoracic disease Background:Recent studies indicate that chronic kidney disease (CKD) is a comorbidity in patients with obstructive sleep apnea (OSA). We hypothesized that the use of the classical muscle-dependent, creatinine-based equation to estimate glomerular filtration rate (GFR) in patients with OSA may be inaccurate due to the extreme body mass index (BMI) of some patients. The aim of this study was to establish the role of cystatin-C-based estimation of GFR for the detection of CKD in patients with OSA and typical comorbidities. Methods:Two hundred and forty consecutive patients with newly diagnosed OSA were enrolled into this cross-sectional study. In all patients estimated GFR (eGFR) was calculated with chronic kidney disease-epidemiology collaboration group (CKD-EPI) equations using creatinine and cystatin-C. All patients were examined for comorbidities. Results:In obese patients with OSA significant differences between GFR estimations based on creatinine and cystatin were found: eGFR based on muscle-dependent creatinine measurement was significantly higher than the muscle-independent eGFR based on cystatin-C measurement. Conclusions:GFR can be routinely screened for using creatinine-based estimations (eGFRcreat). In a selected group of patients with OSA with BMI over 30 kg/m the addition of cystatin-C for assessment of eGFR is suggested. 10.21037/jtd.2020.02.11
    Comparison of serum cystatin C and creatinine levels in determining glomerular filtration rate in children with stage I to III chronic renal disease. Dönmez Osman,Korkmaz Hüseyin Anıl,Yıldız Nalan,Ediz Bülent Renal failure BACKGROUND:Pediatric studies are relatively scarce on the superiority of cystatin C over creatinine in estimation of glomerular filtration rate (GFR). This study measured cystatin C and serum creatinine levels, and compared GFR estimated from these two parameters in patients with chronic renal disease. METHODS:This prospective, observational, controlled study included 166 patients aged 1-18 years diagnosed with stage I to III chronic renal disease, and 29 age- and sex-matched control subjects. In all patients, GFR was estimated via creatinine clearance, Schwartz formula, Zappitelli 1 and Zappitelli 2 formula and the results were compared using Bland-Altman analysis. RESULTS:Patients and controls did not differ with regard to height, body weight, BMI, serum creatinine and serum cystatin levels, and Schwartz formula-based GFR (p > 0.05). There was a significant relationship between creatinine and cystatin C levels. However, although creatinine levels showed a significant association with age, height, and BMI, cystatin C levels showed no such association. ROC analysis showed that cystatin C performed better than creatinine in detecting low GFR. CONCLUSION:Cystatin C is a more sensitive and feasible indicator than creatinine for the diagnosis of stage I to III chronic renal disease. 10.3109/0886022X.2015.1014771
    The fat mass, estimated glomerular filtration rate, and chronic inflammation in type 2 diabetic patients. Šálek Tomáš,Adamíková Alena,Ponížil Petr Journal of clinical laboratory analysis BACKGROUND:The aim of the study was to analyze the degree of obesity and its associations with age, gender, inflammation, an estimated glomerular filtration rate (eGFR), and liver function in type 2 diabetes mellitus (T2DM) patients. METHODS:A total of 874 consecutive adult Caucasian T2DM patients from outpatient diabetic clinic were included in the study. The relative fat mass (RFM) and body mass index (BMI) were used as obesity markers. Serum creatinine and cystatin C were used for the GFR estimation. Serum high-sensitive C-reactive protein (hsCRP) was used as the indicator of inflammation. RESULTS:The median, interquartile range (IQR) of RFM in females was higher than that in males (44.8 (42.3-47.2) % vs 31.3 (28.8-34.1) %, respectively; P < .0001). The median (IQR) of BMI in females was no higher than that in males (30 (27-34) kg/m vs 30 (27-34), respectively; P = .5152). The obesity prevalence was 99% in males and 98% in females according to RFM. BMI recognized obesity in 51% males and 53% females. RFM was positively associated with hsCRP in both males (r  = .296, P < .0001) and females (r  = .445, P < .0001). ALT was positively correlated with eGFRcys in both males (r  = .379, P < .0001) and females (r  = .308, P < .0001). CONCLUSION:The RFM equation leads to higher obesity prevalence compared to BMI. Women have higher RFM compared to men. The kidney function was positively correlated with ALT serum concentrations. 10.1002/jcla.23229
    Glomerular filtration rate estimation using cystatin C alone or combined with creatinine as a confirmatory test. Fan Li,Inker Lesley A,Rossert Jerome,Froissart Marc,Rossing Peter,Mauer Michael,Levey Andrew S Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association BACKGROUND:Glomerular filtration rate (GFR) estimating equations using the combination of creatinine and cystatin C (eGFRcr-cys) are more accurate than equations using either alone (eGFRcr or eGFRcys). New guidelines suggest measuring cystatin C as a confirmatory test when eGFRcr may be inaccurate, but do not specify demographic or clinical conditions in which eGFRcys or eGFRcr-cys are more accurate than eGFRcr nor which estimate to use in such circumstances. METHODS:We compared the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in 1119 subjects in the CKD-EPI cystatin C external validation dataset. Subgroups were defined by eGFRcr, age, sex, diabetes status and body mass index (BMI). The reference test was GFR measured using urinary or plasma clearance of exogenous filtration markers. Cystatin C and creatinine assays were traceable to primary reference materials. Accuracy was defined as the absolute difference in eGFR compared with mGFR. RESULTS:The mean mGFR was 70 ± 41 (SD) mL/min/1.73 m(2). eGFRcys was more accurate than eGFRcr at lower BMI and less accurate at higher BMI, especially at higher levels of eGFRcr. There were small differences in accuracy in people according to the diabetes status. eGFRcr-cys was as accurate or more accurate than eGFRcr or eGFRcys in these and all other subgroups. CONCLUSIONS:eGFRcr-cys, but not eGFRcys, is more accurate than eGFRcr in most subgroups we studied, suggesting preferential use of eGFRcr-cys when serum cystatin C is measured as a confirmatory test to obtain more accurate eGFR. Further studies are necessary to evaluate diagnostic strategies for using eGFRcys and eGFRcr-cys. 10.1093/ndt/gft509
    Removal of body surface area normalisation improves raw-measured glomerular filtration rate estimation by the Chronic Kidney Disease Epidemiology Collaboration equation and drug dosing in the obese. Chew-Harris J S C,Chin P K L,Florkowski C M,George P,Endre Z Internal medicine journal BACKGROUND/AIM:We aimed to compared estimated glomerular filtration rate (eGFR) according to the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI), with (mL/min/1.73 m(2) ) and without body surface area (BSA) normalisation (CKD-EPI_noBSA, mL/min) against measured (99m) Technetium - diethylenepentaacetic acid (Tc-DTPA GFR) (mL/min) in 222 individuals, including 80 with malignancy. METHODS:BSA was calculated for each individual using the Du Bois equation. The CKD-EPI and CKD-EPI_noBSA equations were compared with measured Tc-DTPA GFR with respect to bias, proportion within 30% of GFR (P30) and root mean square error for predicting levels of GFR, and concordance in relation to carboplatin dosing. RESULTS:The mean (SD) for BSA and measured GFR for the entire group was 1.99 (0.25) m(2) and 127 (41) mL/min respectively. The P30 for Tc-DTPA GFR was significantly higher with the CKD-EPI_noBSA (80%) than with the CKD-EPI equation (63%, P = 0.0001). In those with body mass index (BMI) > 30 kg/m(2) , the P30 values for the CKD-EPI_noBSA and CKD-EPI were 74% and 42% respectively (P < 0.0001). Carboplatin dosing concordance for the cancer patients using the CKD-EPI and CKD-EPI_noBSA equation was 71% and 56% respectively (P = 0.07). In 78 individuals with BMI > 30 kg/m(2) , concordance in relation to carboplatin dosing using CKD-EPI_noBSA was 65% compared with 26% with the CKD-EPI (P < 0.0001). CONCLUSION:The CKD-EPI without normalisation (CKD-EPI_noBSA) equation was superior to the CKD-EPI equation in estimating raw-measured Tc-DTPA GFR (mL/min). 10.1111/imj.12791
    Association of Metabolic Syndrome with Chronic Kidney Disease in Elderly Japanese Women: Comparison by Estimation of Glomerular Filtration Rate from Creatinine, Cystatin C, and Both. Kurata Miki,Tsuboi Ayaka,Takeuchi Mika,Fukuo Keisuke,Kazumi Tsutomu Metabolic syndrome and related disorders BACKGROUND:Associations between metabolic syndrome (MetS) and chronic kidney disease (CKD) has not been extensively studied in elderly Asians, who in general have lower body mass index (BMI) than European populations. METHODS:A cross-sectional analysis was conducted including 159 community-living elderly Japanese women. MetS was defined by the modified National Cholesterol Education Program Adult Treatment Panel III criteria, but using a BMI ≥25 kg/m(2) instead of waist circumference and renal function was assessed according to the Kidney Disease Outcomes Quality Initiative CKD classification. Creatinine-based and cystatin C-based estimated glomerular filtration rate (eGFR) and the average of the two eGFRS were used. RESULTS:Prevalence of CKD was much higher when creatinine-based eGFR was used than the prevalence obtained when cystatin-C based equations were used (46.5% vs. 12.6%, P < 0.001). Eighteen (11.3%) women met MetS criteria. Both the presence of MetS and the number of MetS components were associated with higher prevalence of CKD using the average eGFR (all P < 0.05) but not using creatinine-based (P = 0.86) and cystatin C-based (P = 0.12) eGFR alone. Lower average eGFR and higher prevalence of CKD using average eGFR were evident in even women with only one MetS component, 89% of whom had elevated blood pressure. CONCLUSIONS:Prevalence of CKD varied substantially depending on the used equation. In nonobese, elderly Japanese women, both the presence of MetS and the number of MetS components were associated with higher prevalence of CKD and elevated blood pressure may play an important role in these associations. These findings should be confirmed in studies employing more participants with MetS diagnosed using standard criteria (waist circumference instead of BMI). 10.1089/met.2015.0085
    Impact of lean mass and bone density on glomerular filtration rate estimation in people living with HIV/AIDS. Isnard Bagnis Corinne,Pieroni Laurence,Inaoui Rachida,Maksud Philippe,Lallauret Stéphanie,Valantin Marc-Antoine,Tubiana Roland,Katlama Christine,Deray Gilbert,Courbebaisse Marie,Tourret Jérôme,Tezenas du Montcel Sophie PloS one CONTEXT:Chronic kidney disease is a frequent complication in persons living with HIV/AIDS. Although previous studies have suggested that the CKD-EPI formula is appropriate to estimate glomerular filtration rate (GFR) in HIV-positive adults with normal kidney function, the optimal way to estimate GFR in those with Stage 3 chronic kidney disease is not known. Moreover, the impact of muscle mass on creatinine level and GFR estimation is unknown. AIM AND METHODS:Our study aimed to evaluate the accuracy of different diagnostic tests available compared to the gold standard measurement of GFR. A group of 44 HIV-1 patients with an estimated GFR between 60 and 30 ml/min/1.73 m2 were included in a single-center cross-sectional study. Serum creatinine and cystatin C were measured. GFR was estimated using Cockcroft-Gault, MDRD, sMDRD, CKD-EPI, CKD-EPIcyst, and CKD-EPIcyst/creat formulae and was measured using isotopic Chrome51 EDTA clearance. Bone density and muscle mass were measured by DXA scan. RESULTS:Mean age was 62±10 years. Mean BMI was 23±4 kg/m2. Prevalence of diabetes was 30% and of hypertension was 47%. Viral load was <40 copies/ml for 90% of the patients, and mean CD4 count was 446±191 cells/mm3. Mean measured GFR was 63.4±16.5 ml/min/1.73 m2. All formulae under-estimated GFR. The best relative precision and accuracy were provided by the CKP-EPI formula. sMDRD, CKD-EPIcyst, and CKD-EPIcyst/creat performed worse than the CKD-EPI formula. Body composition did not significantly influence accuracy or precision of GFR estimation. CONCLUSION:In HIV-infected patients in stable immunovirologic conditions with CKD stage 3 and high prevalence of metabolic associated conditions, the CKD-EPI formula performed best, although all formulae under estimate GFR. 10.1371/journal.pone.0186410