Division of Nephrology, Department of Medicine, Queen's University, Kingston, Ontario, Canada.
Clin Chem. 2010 Mar;56(3):474-7. doi: 10.1373/clinchem.2009.135111. Epub 2009 Dec 3.
The new Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was developed to address the systematic underestimation of the glomerular filtration rate (GFR) by the Modification of Diet in Renal Disease (MDRD) Study equation in patients with a relatively well-preserved kidney function. The performance of the new equation for kidney transplant recipients (KTRs) is unknown.
We used the plasma clearance of (99m)Tc-diethylenetriamine pentaacetic acid to measure the GFR in a cohort of 207 stable KTRs and estimated the GFR with the new CKD-EPI equation.
The mean bias for the CKD-EPI equation of -4.5 mL x min(-1) x (1.73 m(2))(-1) was lower than that of the 4-variable MDRD Study equation; however, the 2 equations showed similar variation of individual biases around the mean or median bias, so that only modest improvement was seen in the overall percentage of GFR estimates within 30% of the measured GFR (84% vs 77% for the CKD-EPI vs MDRD Study equations, respectively). In the cohort with a GFR >60 mL x min(-1) x (1.73 m(2))(-1) (n = 98), the CKD-EPI bias was much less than that of the MDRD Study equation [-7.4 mL x min(-1) x (1.73 m(2))(-1) vs -14.3 mL x min(-1) x (1.73 m(2))(-1)], and an accuracy of + or - 30% was seen for 89% of GFR estimates, compared with 77% with the MDRD Study equation. The variation of the individual biases around the mean bias remained substantial [SD = 13.7 mL x min(-1) x (1.73 m(2))(-1)].
The CKD-EPI equation shows improved estimation ability, and we recommend that it replace the MDRD Study equation as the currently preferred creatinine-based estimating equation for KTRs. The precision of GFR estimates obtained with the CKD-EPI equation remains suboptimal, however, and we recommend that research on other markers of GFR, such as cystatin C and beta-trace protein, be pursued.
新的慢性肾脏病流行病学合作（CKD-EPI）方程的开发是为了解决改良肾脏病饮食研究（MDRD）方程在肾小球滤过率（GFR）系统低估的问题，特别是在肾功能相对保存的患者中。新方程在肾移植受者（KTR）中的性能尚不清楚。
我们使用（99m）Tc-二乙三胺五乙酸的血浆清除率来测量 207 例稳定 KTR 的 GFR，并使用新的 CKD-EPI 方程估计 GFR。
新 CKD-EPI 方程的平均偏差为-4.5 mL x min(-1) x (1.73 m(2))(-1)，低于 4 变量 MDRD 研究方程；然而，这两个方程在个体偏差的平均值或中位数偏差周围显示出相似的变化，因此只有在 GFR 估计值与实测 GFR 的差异在 30%以内的总体百分比有适度提高（分别为 84%和 77%，对于 CKD-EPI 和 MDRD 研究方程）。在 GFR >60 mL x min(-1) x (1.73 m(2))(-1)的队列中（n = 98），CKD-EPI 偏差远小于 MDRD 研究方程[-7.4 mL x min(-1) x (1.73 m(2))(-1)比-14.3 mL x min(-1) x (1.73 m(2))(-1)]，89%的 GFR 估计值的准确性为+或-30%，而 MDRD 研究方程为 77%。个体偏差围绕平均值的变化仍然很大[SD = 13.7 mL x min(-1) x (1.73 m(2))(-1)]。
CKD-EPI 方程显示出更好的估计能力，我们建议用它代替 MDRD 研究方程作为目前首选的基于肌酐的 KTR 估算方程。然而，CKD-EPI 方程获得的 GFR 估计的精度仍然不理想，因此我们建议继续研究其他 GFR 标志物，如胱抑素 C 和β-痕迹蛋白。
