不同肾小球滤过率评估方程在慢性肾脏病患者中适用性的比较

目的：比较肾脏病膳食改良试验（MDRD）和Cock—croft—Gault（cG）方程以及国内的两个校正MDRD方程对慢性肾脏病（CKD）患者预测肾小球滤过率（GFR）的适用性。方法：选择2006年--2008年646例非透析CKD患者,用简化MDRD和CG公式以及两个国内校正公式（MDRD1、MDRD2）计算估测GFR（eGFR）,并进行相关性、偏离度、精密度的比较,以及比较不同CKD分期估测GFR的准确性、偏差中位数。结果：（1）MDRD1方程不论在精密度、偏离度、绝对偏差方面都明显优于其他的方程。（2）MDRD1方程的30％和50％准确率上明显高于其他方程（P〈0．05）。（3）CG明显低估了GFR,MI）RD和MDRD2在Ⅳ期低估了GFR,在Ⅱ、Ⅲ期高估了GFR,MDRD1在Ⅲ期高估了GFR。结论：经过校正的MDRD1方程明显优于CG、简化MDRD、MDRD2方程。     

不同肾功能评估公式在PAP酶法肌酐检测时临床适用性比较

目的：探讨不同肾小球滤过率（GFR）计算公式在肾功能评估中的差异。方法：以99mTc-DTPA肾动态显像法检测的GFR（rGFR）为参照值,对263例符合CKD入选标准的患者采用PAP酶法检测Scr,并对CG公式、MDRD公式、简化MDRD公式和中国人改良MDRD公式（C-MDRD）进行偏离度、精确度和准确性比较。结果：rGFR与CG、MDRD、简化MDRD和C-MDRD估测的eGFR均呈显著相关,r分别是0.821、0.870、0.856、0.856（均P〈0.001）。4种公式的偏离度分别是1221.04、2172.12、2518.45和7295.78,绝对偏差的中位数分别是：14.57、12.48、14.44和25.55;C-MDRD公式与其他3种公式有统计学差异（P〈0.001）,30%准确性分别是60.5%、61.2%、56.3%和38.8%。结论：本组患者行CG、MDRD、简化MDRD和C-MDRD公式估测的eGFR与rGFR相关性好;在PAP酶法测定肌酐条件下,综合偏离度、精确度和准确性分析,MDRD公式临床适用性最佳,而C-MDRD公式最差。     

三种肾小球滤过率检测方法的实用性探讨

目的：以^99mTc—DPTA血浆清除率为标准，对24h内生肌酐清除率（Ccr）、Cookeroft—Gault（CG）方程和简化MDRD（modification of diet in renal disease）方程进行比较，评价三种方程在慢性肾脏疾病（CKD）患者中的应用。方法：选择139例各种慢性肾脏疾病患者，将Ccr、CG方程和简化MDRM方程估算的肾小球滤过率（GFR）用体表面积（BSA）标准化，与BSA标准化的^99mTc—DTPA测得的GFR（^99mTc—GFR）在不同CKD分期进行比较。结果：CKD第一至第五期：Ccr与^99mTc—GFR相关系数r分别为：0．79、0．71、0．64、0．59、0．52；Ccr在ROC曲线下面积平均为0．79。CG—GFR与^99mTc—GFR相关系数r分别为：0．85、0．78、0．72、0．67、0．61；CG—GFR在ROC曲线下面积平均为0．83。MDRD—GFR与^99mTc—GFR相关系数r分别为：0．83、0．76、0．69、0．65、0．59；MDRD—GFR在ROC曲线下面积平均为0．82。在CKD不同分期三种方程的GFR估算值与^99mTc—GFR差异均有显著意义（P均〈0．001）。结论：三种方程的GFR估算值与^99mTc—GFR均有较好的相关性和ROC曲线下面积，以CG方程最好，其次为简化MDRD方程，Ccr最低，但三种方程估算值与^99mTc—GFR测定值差异均有显著意义。上述方程直接应用于我国CKD患者时，应对其进行适当修正。     

肾小球滤过率评估方程在中国糖尿病合并慢性肾脏病患者中的适用性评价

目的探讨临床上使用广泛的慢性肾脏病流行病学协助组(CKD-EPI)肾小球滤过率(GFR)评估方程、改良肾脏病膳食改良试验(MDRD)方程与近年来针对中国人开发的Feng方程、针对中国糖尿病患者改良的CKD-EPI_(糖尿病)方程在中国糖尿病合并慢性肾脏病(CKD)患者中的适用性,进而为临床中准确估测糖尿病合并CKD患者GFR提供更精确的依据。方法选取2型糖尿病合并CKD患者160名。收集患者性别、年龄、身高、体质量、血肌酐(Scr)及胱抑素C(Cys C)。以~(99m)Tc-DTPA肾动态显像法测定的GFR作为参考GFR(rGFR)。使用中国改良MDRD方程、CKD-EPI_(Scr)方程、CKD-EPI_(Cys C)方程、CKD-EPI_(Scr-Cys C)方程、CKD-EPI_(糖尿病)方程、Feng_(Cys C)方程及Feng_(Scr-Cys C)方程对估算GFR(eGFR)进行计算。采用Pearson相关性分析及κ检验比较各方程eGFR与rGFR之间的相关性及分期一致性,并使用Bland-Altman分析法比较各方程eGFR与rGFR的一致性限度。各方程eGFR之间的比较使用偏倚、精确度、10%准确率、30%准确率、50%准确率。定义GFR60 mL·min~(-1)·(1.73 m~2)~(-1)为肾功能不全的诊断标准,通过ROC曲线比较各方程诊断肾功能不全的效能。根据rGFR将患者分为A组(CKD 4～5期)、B组(CKD 3期)、C组(CKD 1～2期),比较不同分组中各方程的适用性。结果在各方程eGFR之间的比较中,CKD-EPI_(糖尿病)方程偏倚最小,与Feng_(Cys C)方程、Feng_(Scr-Cys C)方程比较差异有统计学意义(P0.05);精确度最高,与改良MDRD方程、CKD-EPI_(Cys C)方程比较差异有统计学意义(P0.05)。在7种方程的准确率比较中,CKD-EPI_(糖尿病)方程10%、30%准确率均最高,与简化MDRD方程、CKD-EPI_(Scr)方程、CKD-EPI_(Cys C)方程比较差异均有统计学意义(P0.05)。Bland-Altman分析显示CKD-EPI_(糖尿病)方程一致性限度最佳。在A组患者中,CKD-EPI_(Cys C)方程eGFR与rGFR均值比较差异无统计学意义,偏倚最小,50%、30%准确率最高。B组患者与总体患者类似,CKD-EPI_(糖尿病)方程偏倚最小,精确度最高,10%、30%、50%准确率均最高。结论在7种方程的比较中,CKD-EPI_(糖尿病)方程eGFR与rGFR拟合度最佳。在不同分组的比较中,CKD 4～5期患者CKD-EPI_(Cys C)方程eGFR与rGFR拟合度最佳,CKD 3期患者CKD-EPI_(糖尿病)方程eGFR与rGFR拟合度最佳,可分别用于估测糖尿病合并CKD不同分组患者的GFR。     

不同公式估算慢性肾脏病患者肾小球滤过率的结果评价

目的探讨不同估算公式估算慢性肾脏病（CKD）患者肾小球滤过率（GFR）在肾功能评价中的价值。方法选择CKD患者239例,所有患者同步检测99锝-二乙烯三胺五乙酸（^99mTc-DTPA）、GFR、血肌酐（SCr）等。将^99mTc-DTPA测定的GFR作为参照,并用肾脏病膳食改良试验（MDRD）公式、Cockcroft-Gault公式、简化MDRD公式及慢性肾脏病流行病合作研究（cKD-EPI）公式计算估测GFR,比较不同CKD分期中各估算公式估算的GFR的准确性。结果各估算公式估算的GFR值均高于^99mTc-DTPA,MDRD公式偏离程度最大;各估算公式估算的GFR值与^99mTc-DTPA检查的GFR结果有相关性,CKD-EPI公式相关性最高。结论CKD-EPI公式估算肾功能更接近^99mTc-DTPA的结果,但仍需进一步校正。     

MDRD方程预测肾小球滤过率的临床应用评价

目的以99mTc-DTPA血浆清除率为标准,对MDRD方程7、简化MDRD方程和Cockcroft-Gault方程进行比较,评价3个方程在慢性肾脏病患者中的应用.方法选择慢性肾脏病患者199例,年龄均＞18岁,诊断均符合美国NKF-K/DOQI关于慢性肾脏病定义,且无肾功能急性恶化因素,无水肿和肌肉萎缩或肢体缺如.记录性别、年龄、身高和体重.用MDRD方程7和简化MDRD方程计算GFR,Cockcroft-Gault方程计算Ccr后用体表面积标准化.弹丸式静脉注射1 ml 185 MBq/ml99mTc-DTPA,分别于注射后2 h和4 h取血,测量其血浆放射性计数,并检测血清肌酐、尿素、白蛋白,计算99mTc-DTPA的血浆清除率,并用体表面积标准化作为GFR测量值.各方程计算值分别与GFR测量值进行比较.结果199例中男112例,女87例,平均年龄(51.58±14.9)岁.慢性肾脏病的病因包括肾积水63例,原发或继发性肾小球疾病46例、慢性肾小管间质疾病16例、其它或病因不明74例.MDRD方程7、简化MDRD方程和Cockcroft-Gault方程的估计值与GFR测量值的相关系数(r)分别为0.84,0.81和0.82;3个方程的计算值均显著低于GFR测量值,MDRD方程7、简化MDRD方程与测量值的偏差[分别为-4.37和-4.83 ml·min-1(1.73m2)-1]和绝对偏差[分别为11.71和10.79 ml·min-1(1.73m2)-1]均低于体表面积标准化Cockcroft-Gault方程的偏差[-7.18 ml·min-1·(1.73m2)-1]和平均绝对偏差[12.95 ml·min-1·(1.73 m2)-1].3个方程偏离测量值分别为21%、21%和22.5%,Cockcroft-Gault方程的偏离程度最大;计算值落在测量值±15%,±30%和±50%范围内的病例百分数分别为39.2%、39.7%和36.18%,72.36%、70.85%和63.82%,94.47%、92.45%和90.45%.结论MDRD方程7、简化MDRD方程和Cockcroft-Gault方程的GFR计算值均显著低于99mTc-DTPA血浆清除率,但MDRD方程7和简化MDRD方程偏离测量值程度低于体表面积标准化的Cockcroft-Gault方程.MDRD方程应用于我国,需按照我国人群特征将MDRD方程中的常量进行适当调整.     

不同方法对肾功能评估的价值

目的探讨临床上常用的几种肾功能评估方法的相对准确性,寻求更为简便、快捷的肾功能评估方法。方法选择慢性肾脏病（CKD）患者80例,分别用^99mTc-DTPA肾动态显像法测定肾小球滤过率（GFR）,同时检测患者血肌酐（SCr）、血清胱抑素C（CysC）浓度,根据SCr分别用Cock-croft-Gault（C-G）方程和简化MDRD方程估算肾小球滤过率（分别为eGFR1、eGFR2）。按GFR值将患者分为4组,即A组：CKD1期;B组：CKD2期;C组：CKD3期;D组：CKD4期;排除CKD5期的患者。观察所有和各组患者eGFR1、eGFR2、SCr、CysC与GFR的相关性。结果总样本中,eGFR1、eGFR2与GFR呈正相关,SCr、CysC与GFR呈负相关（P〈0．01）。在各组中,A组：eGFR1、eGFR2、SCr与GFR之间均无明显相关性（P〉0．05）;而B、C、D组中eGFR1、eGFR2与GFR呈正相关（P〈0．01）,SCr与GFR呈负相关（P〈0．05）;CysC在A、B、C、D各组中均与GFR呈负相关（P〈0．01）。结论CKD2、3、4期患者eGFR1、eGFR2、SCr与GFR均有一定的相关性,但不论何期CKD患者,CysC均能准确反映其肾功能状况,且更加简便、快捷。     

CKD-EPI方程对基于简化MDRD方程的慢性肾脏病患者分期的影响

目的 研究CKD-EPI方程对基于简化MDRD方程的慢性肾脏病（CKD）患者分期的影响。 方法 选择2008年6月至2009年9月在我院肾内科就诊的CKD患者450例,分别用简化MDRD方程和CKD-EPI方程估测GFR（eGFR）。用Bland-Altman曲线对二方程计算的eGFR进行一致性检验。根据eGFR对CKD患者分期,对基于不同方程的CKD患者的分期情况进行Kappa检验。 结果 简化MDRD方程和CKD-EPI方程估测eGFR的一致性好,但CKD-EPI-eGFR较MDRD-eGFR平均高出约2.4 ml·（min）-1·（1.73 m2）-1。简化MDRD方程和CKD-EPI方程在CKD1、2、3A、3B、4 和5期符合率分别为97.10%（n=67）,80.77%（n=105）,60.86%（n=48）,87.69%（n=57）,90.38%（n=47）和98.18%（n=54）。Kappa检验提示2方程对CKD患者分期的一致性极好[Kappa值0.913（95%CI：0.881~0.945）]。然而,若依据CKD-EPI方程结果,仍须将由简化MDRD方程分类至60～89 ml·（min）-1·（1.73 m2）-1及45～59 ml·（min）-1·（1.73 m2）-1两组中的19.23%（n=25）及39.24%（n=31）的患者进行再次分类,且均被归为更高eGFR等级。 结论 CKD-EPI方程可“上调”基于简化MDRD方程的CKD 2期～3A期患者的分期等级,纠正了简化MDRD方程对CKD的过度诊断。     

六种肾小球滤过率估算方程对梗阻性肾病患者肾小球滤过率的比较

目的:比较六种肾小球滤过率估算方程在评价中国梗阻性肾病患者肾小球滤过率(Glomerular filtration rate,GFR)的适用性,即3种MDRD(Modification of Diet in Renal Disease,MDRD)公式和3种CKD-EPI(Chronic Kidney Disease Epidemiology Collaboration,CKD-EPI)公式。方法:选择2012年01月~2016年12月在我院完成99 m Tc-DTPA肾动态显像(ECT)检查的梗阻性肾病患者476例,以ECT所测得的GFR(m GFR)作为参考标准,用目前常用以上6种方程估算GFR(e GFR)为对照,分析各e GFR与m GFR的相关性,并就6种e GFR的估测偏差、精确度、准确率及诊断准确性进行比较。结果:本研究结果表明各e GFR与m GFR均显示高度的相关性(P0.01)。在数值诊断上,各e GFR与CKD-EPI联合方程e GFR间的估测偏差、精确度、15%、30%及50%范围的准确度比较差异有统计学意义(P0.05)。CKD-EPI方程较MDRD方程显示出较好的数值准确度,CKD-EPI联合方程所估算的GFR在数值上准确度最高。在诊断方面,3种CKD-EPI方程的ROC曲线下面积、分期诊断准确度及其一致性比3种MDRD方程更好,其中,CKD-EPI联合方程ROC曲线下面积最大(0.886),分期诊断准确度最高(44.1%),Kappa值最大(0.254,CI[0.179,0.311])。在亚组分析中,不同的亚组最适方程有所差别,其中简化MDRD与CKD-EPI联合方程在不同亚组中的适用性较高。结论:CKD-EPI方程对中国的梗阻性肾病患者较MDRD方程有更高的适用性,其中CKD-EPI联合方程所估算的e GFR值与m GFR值相关性最好,准确度最高,偏倚最小,诊断性能最好。     

7种肾小球滤过率评估方程在慢性肾脏病患者中的比较

目的：比较不同肾小球滤过率（GFR）评估方程在慢性肾脏病（CKD）患者中的诊断价值。方法：选择CKD各期患者108例,对照20例,应用ELISA法测定血清Cystatin C浓度、^99m Tc-DTPA清除率测定GFR、全自动生化分析仪检测血清肌酐（Scr）,并用7种公式计算GFR（eGFR）。结果：在CKD2期,MDRD、简化MDRD与GFR比较有统计学差异,在CKD3期,CG-eGFR与GFR比较有统计学差异。而Cys-eGFR在CKD1～5期与GFR均无统计学差异。在CKD2期、3期,4种Cys-eGFR方程与GFR的相关性均显著优于CG和MDRD公式。而在1期、4期和5期,各方法测定eGFR与同位素GFR的相关性相当。在GFR〈60ml.min^-1.1.73m^-2的CKD患者中,4种Cys-eGFR的ROC曲线下面积大于Cr-eGFR方程,有统计学意义;在GFR〈30ml.min^-1.1.73m^-2的CKD患者中,ROC曲线下面积比较无统计学差异。结论：cys-eGFR在肾功能轻中度减退的患者中,优于CG和MDRD,在肾衰竭后期,诊断价值同Cr-eGFR公式。     

Modified glomerular filtration rate estimating equation for Chinese patients with chronic kidney disease

The Modification of Diet in Renal Disease (MDRD) equations provide a rapid method of assessing GFR in patients with chronic kidney disease (CKD). However, previous research indicated that modification of these equations is necessary for application in Chinese patients with CKD. The objective of this study was to modify MDRD equations on the basis of the data from the Chinese CKD population and compare the diagnostic performance of the modified MDRD equations with that of the original MDRD equations across CKD stages in a multicenter, cross-sectional study of GFR estimation from plasma creatinine, demographic data, and clinical characteristics. A total of 684 adult patients with CKD, from nine geographic regions of China were selected. A random sample of 454 of these patients were included in the training sample set, and the remaining 230 patients were included in the testing sample set. With the use of the dual plasma sampling (99m)Tc-DTPA plasma clearance method as a reference for GFR measurement, the original MDRD equations were modified by two methods: First, by adding a racial factor for Chinese in the original MDRD equations, and, second, by applying multiple linear regression to the training sample and modifying the coefficient that is associated with each variable in the original MDRD equations and then validating in the testing sample and comparing it with the original MDRD equations. All modified MDRD equations showed significant performance improvement in bias, precision, and accuracy compared with the original MDRD equations, and the percentage of estimated GFR that did not deviate >30% from the reference GFR was >75%. The modified MDRD equations that were based on the Chinese patients with CKD offered significant advantages in different CKD stages and could be applied in clinical practice, at least in Chinese patients with CKD.     

中国肾小球滤过率评估方程在慢性肾小球肾炎患者的适用性评价

目的：评价现有在中国人群基础上开发的肾小球滤过率（GFR）评估方程在慢性肾小球肾炎患者的适用性。方法：选择143例慢性肾小球肾炎患者,用中国方程、瑞金方程、MDRD1方程和简化MDRD方程,分别计算GFR值,与^99mTc—DTPA测的GFR（sGFR）进行比较。结果：Bland—Altman分析显示MDRD1方程和瑞金方程估计的GFR和sGFR的一致性较好,但所有各方程估计的GFR和出FR的一致性限度均超过事先规定的专业界值。线性回归结果显示,MDRD1方程和瑞金方程估测的GFR与X轴的斜率较其他方程更接近0。在所有方程中,MDRD1方程和中国9方程偏差较小,瑞金方程估测GFR30％符合率和50％符合率均最高,但瑞金方程估测GFR30％符合率依然低于70％。在慢性肾脏病不同分期中,瑞金方程和MDRD1方程较其他方程有较小的偏差和更优的准确性。结论：当血肌酐的测定方法为酶法时,如直接应用现有在中国人群基础上开发的肾小球滤过率评估方程评估慢性肾小球肾炎患者肾功能,可能会产生明显的偏差。     

Comparison of 99mTc-DTPA renal dynamic imaging with modified MDRD equation for glomerular filtration rate estimation in Chinese patients in different stages of chronic kidney disease.

BACKGROUND: The renal dynamic imaging method (modified Gate's method) with (99m)Tc-diethylene triamine pentaacetic acid ((99m)Tc-DTPA) is simple and less time consuming for glomerular filtration rate (GFR) estimation than other methods. However, its diagnostic performance as a surrogate marker of GFR is questioned increasingly. Recently, the modified Modification of Diet in Renal Disease (MDRD) study equation based on data from Chinese patients of chronic kidney disease (CKD) showed significant performance improvement. In the present study, the renal dynamic imaging methods and the modified abbreviated MDRD equation were compared with the plasma clearance method. METHODS: Four hundred and eighty two patients with CKD were selected. GFR were estimated simultaneously using three methods: (i) modified Gate's method (gGFR); (ii) the modified abbreviated MDRD equation (c-aGFR) and (iii) dual plasma sampling method (rGFR). Using rGFR as the reference method, gGFR and c-aGFR were compared with rGFR in each stage of CKD. RESULTS: Both gGFR and c-aGFR were correlated well with rGFR (r(gGFR) = 0.81 and r(c-aGFR) = 0.90, P < 0.001). In the overall performance, c-aGFR had less bias (849.5 vs 933.1 arbitrary units), higher precision (57 vs 78.4 ml/min/1.73 m(2)) and higher accuracy than gGFR. For gGFR, the 15, 30 and 50% accuracies were 32.4, 56.0 and 79.1%, respectively; for c-aGFR, the corresponding accuracy rose to 43.2%, 75.5% and 90.9%, respectively. In each stage of CKD, the modified abbreviated MDRD equation also outperformed the modified Gate's method in the GFR estimation. CONCLUSION: Our results indicated that the performance of the renal dynamic imaging in total GFR estimation was not better than the modified abbreviated MDRD equation in our patient group, and should not be used as a surrogate marker of GFR, especially in clinical trials. We presume that the dynamic renal imaging methods for estimation of GFR can be improved by using proper reference GFR, more adequate background subtraction and soft-tissue attenuation correction, in a relatively larger sample size.     

中国肾小球滤过率评估方程在慢性肾脏病患者的应用评价

目的 评价现有在中国人群基础上开发的肾小球滤过率(GFR)评估方程在慢性肾脏病(CKD)患者的适用性。 方法 选择327例CKD患者,用中国方程、瑞金方程分别预测GFR值,与体表面积标准化99mTc-DTPA测的GFR（sGFR）进行比较。 结果 Bland-Altman分析显示瑞金方程估计的GFR和sGFR的一致性最好,但所有方程估计的GFR和sGFR的一致性限度均超过事先规定的专业界值。线性回归结果显示,瑞金方程和MDRD-1方程估测的GFR与X轴的斜率较其他方程更小。在所有方程中,瑞金方程估测GFR 15%符合率、30%符合率和50%符合率均最高,但瑞金方程估测GFR 30%符合率依然低于70%。在CKD的不同分期中,瑞金方程估测GFR 15%符合率、30%符合率和50%符合率均较高。 结论 当血肌酐的测定方法为酶法时,如果直接应用目前在中国人群基础上开发出的GFR评估方程预测GFR,可能会产生明显的偏差。有必要进行更大规模试验,进一步评估和验证中国方程和瑞金方程在中国人群的适用性。     

Estimation of glomerular filtration rate by the MDRD study equation modified for Japanese patients with chronic kidney disease

Background

Accurate estimation of the glomerular filtration rate (GFR) is crucial for the detection of chronic kidney disease (CKD). In clinical practice, GFR is estimated from serum creatinine using the Modification of Diet in Renal Disease (MDRD) study equation or the Cockcroft-Gault (CG) equation instead of the time-consuming method of measured clearance for exogenous markers such as inulin. In the present study, the equations originally developed for a Caucasian population were tested in Japanese CKD patients, and modified with the Japanese coefficient determined by the data.

Methods

The abbreviated MDRD study and CG equations were tested in 248 Japanese CKD patients and compared with measured inulin clearance (Cin) and estimated GFR (eGFR). The Japanese coefficient was determined by minimizing the sum of squared errors between eGFR and Cin. Serum creatinine values of the enzyme method in the present study were calibrated to values of the noncompensated Jaffé method by adding 0.207?mg/dl, because the original MDRD study equation was determined by the data for serum creatinine values measured by the noncompensated Jaffé method. The abbreviated MDRD study equation modified with the Japanese coefficient was validated in another set of 269 CKD patients.

Results

There was a significant discrepancy between measured Cin and eGFR by the 1.0 × MDRD or CG equations. The MDRD study equation modified with the Japanese coefficient (0.881 × MDRD) determined for Japanese CKD patients yielded lower mean difference and higher accuracy for GFR estimation. In particular, in Cin 30–59?ml/min per 1.73?m², the mean difference was significantly smaller with the 0.881 × MDRD equation than that with the 1.0 × MDRD study equation (1.9 vs 7.9?ml/min per 1.73?m²; P P 2, the accuracy was significantly higher, with 85% vs 69% of the points deviating within 50% (P P 2.

Conclusions

Although the Japanese coefficient improves the accuracy of GFR estimation of the original MDRD study equation, a new equation is needed for more accurate estimation of GFR in Japanese patients with CKD stages 3 and 4.     

Improved GFR estimation by combined creatinine and cystatin C measurements

Plasma creatinine may not reflect glomerular filtration rate (GFR) especially in the early stages of chronic kidney disease (CKD). Plasma cystatin C (cysC), however, has the potential to more accurately determine early GFR reduction. We sought to improve the creatinine-based GFR estimation by including cysC measurements. We derived a reference GFR from standard dual plasma sampling (99m)Tc-DTPA clearance in a training cohort of 376 randomly selected adult Chinese patients with CKD. We compared reference values to estimated GFR and applied multiple regression models to one equation based solely on cysC, and to another combining plasma creatinine (Pcr) and cysC measurements of the training cohort. The results were validated by testing an additional 191 patients. The difference, precision, and accuracy of the two estimates were compared with the modified Modification of Diet in Renal Disease (MDRD) equation for Chinese patients, and another estimate combining cysC and modified MDRD calculations. The estimated GFR combining Pcr and cysC measurements more accurately matched the reference GFR at all stages of CKD than the other equations, particularly in patients with near-normal kidney function.     

A modified Cockcroft-Gault formula taking into account the body surface area gives a more accurate estimation of the glomerular filtration rate

We sought to validate the improvement by adjustment for body surface area (BSA) of the accuracy of the original Cockcroft-Gault equation to estimate glomerular filtration rate (GFR), in a prospective cross-sectional study of 269 European patients with chronic kidney disease (CKD). We compared 3 methods: original Cockcroft-Gault equation, modified Cockcroft-Gault formula adjusted for BSA and abbreviated Modification of Diet in Renal Disease (MDRD) equation, using inulin clearance. Statistical analyses comprised repeated-measures analysis of variance (ANOVA), determination of the Pearson coefficient of correlation and a Bland-Altman concordance study. The ability of the GFR estimates to properly categorize patients in K/DOQI stages of CKD was also examined. Inulin clearance differed significantly from the standard Cockcroft-Gault method (ANOVA, p<0.001) and the abbreviated MDRD method (ANOVA, p<0.001) but not from the BSA-modified Cockcroft-Gault formula. Inulin clearance correlated better with the BSA-modified Cockcroft-Gault formula (r=0.88) and abbreviated MDRD equation (r=0.87) than with the standard Cockcroft-Gault equation (r=0.82). In concordance studies, bias was far smaller with the BSA-modified Cockcroft-Gault formula (mean bias -1.75 ml/min), than with the standard Cockcroft-Gault equation (mean bias -4.72 ml/min). The bias of the abbreviated MDRD was larger (mean bias +6.24 ml/min). Only patients with CKD stage 1 were better categorized with the BSA-modified Cockcroft-Gault formula and with the standard Cockcroft-Gault estimate than with the abbreviated MDRD equation. We conclude that adjustment for body surface area improves accuracy of the original Cockcroft-Gault equation.     

Chronic kidney disease stage in renal transplantation classification using cystatin C and creatinine-based equations.

BACKGROUND: Current clinical guidelines recommend that renal transplant recipients (RTRs) be classified into chronic kidney disease (CKD) stage using a creatinine-based estimate of glomerular filtration rate (GFR). However, creatinine-based equations are inaccurate in RTRs leading to frequent CKD stage misclassification. It is not known whether the classification of CKD stage would be improved using a cystatin C-based estimate of GFR. METHODS: We measured (99m)Tc-DTPA GFR, cystatin C and creatinine in 198 stable RTRs. GFR was estimated using cystatin C-based equations (Filler, Le Bricon and Rule) and four creatinine-based equations. We determined the proportion, overall and by CKD stage, that were classified correctly by each equation as compared to the (99m)Tc-DTPA GFR. RESULTS: The Filler equation correctly classified 76% of patients compared to only 65% with the abbreviated modification of diet in renal disease (MDRD) equation and 69% with the Cockcroft-Gault equation. In CKD stages two and four, the Filler equation correctly classified 77% and 60% of patients whereas the abbreviated MDRD equation correctly classified 46% and 93% of patients. The area under the curve by receiver operating curve analysis for overall stage classification was uniformly poor for all equations (0.52-0.56). CONCLUSIONS: The cystatin C-based Filler and Le Bricon GFR estimates classified slightly more patients into the correct CKD stage than the standard creatinine-based equations in stable RTRs although the overall diagnostic accuracies were similar. The differences are modest and prospective studies will be needed to determine if the adoption of these equations for classification would lead to improved recognition of CKD complications or patient care.     

Assessment of glomerular filtration rate in elderly patients with chronic kidney disease

Purpose

We sought to evaluate various glomerular filtration rate (GFR) estimating equations in elderly patients with chronic kidney disease (CKD).

Methods

A total of 332 Chinese elderly patients with CKD who had undergone technetium-99m diethylenetriaminepentaacetic acid (^99mTc-DTPA) renal dynamic imaging were enrolled. The MDRD equation, the re-expressed MDRD equation, the Chinese equation, the Ruijin equation, the previously Japanese equation, the new Japanese equation, the CKD-EPI equation, and the BIS1 equation were compared.

Results

The median of difference between estimated GFR and standard GFR ranged from ?9.78 to 1.79 ml/min/1.73 m². The interquartile range of difference ranged from 12.38 to 20.87 ml/min/1.73 m². Accuracy with a deviation <30 % ranged from 44.9 to 66.3 %. However, none of the equations had accuracy up to the 70 % level. Bland–Altman analysis demonstrated that the precision ranged from 50.5–87.6 ml/min/1.73 m². The slopes of regression line ranged from ?0.26 to 0.55 and the intercepts ranged from ?18.71 to 11.07. In both the overall performance and the performances in different stage of CKD, GFR estimated by the BIS1 equation performed better results.

Conclusion

None of the GFR estimating equations are suitable for the specific Chinese population tested. At present, the BIS1 equation may be the optimal one for elderly Chinese CKD patients.