Bevc Sebastjan, Hojs Radovan, Ekart Robert, Gorenjak Maksimiljan, Puklavec Ludvik
Department of Nephrology, University Medical Center Maribor, Maribor, Slovenia.
Ther Apher Dial. 2011 Jun;15(3):261-8. doi: 10.1111/j.1744-9987.2011.00948.x.
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.
尽管血清肌酐水平在评估老年人肾小球滤过率（GFR）方面 notoriously unreliable ，但血清肌酐浓度和基于血清肌酐的公式，如肾脏病膳食改良研究方程（MDRD），是最常用的评估GFR的指标。最近，基于血清胱抑素C的公式、新的肌酐公式（慢性肾脏病流行病学协作组肌酐公式（CKD - EPI肌酐公式））以及同时使用血清肌酐和胱抑素C的方程（CKD - EPI肌酐和胱抑素公式）被提议作为新的GFR指标。我们研究的目的是在老年人中将MDRD公式、CKD - EPI肌酐公式、CKD - EPI肌酐和胱抑素公式以及简单的胱抑素C公式（100/血清胱抑素C）与（51）Cr - EDTA清除率进行比较。总共纳入了317名年龄大于65岁的成年白种人患者。对每位患者测定了（51）Cr - EDTA清除率、血清肌酐和血清胱抑素C，并使用MDRD公式、CKD - EPI公式和简单的胱抑素C公式计算GFR。发现（51）Cr - EDTA清除率与所有公式之间存在统计学上的显著相关性。在以GFR 45 mL/min/1.73 m²为临界值的受试者工作特征（ROC）曲线分析中，同时使用血清肌酐和胱抑素C的方程（CKD - EPI肌酐和胱抑素公式）比MDRD公式（P < 0.013）或CKD - EPI肌酐公式（P < 0.01）具有更高的诊断准确性，但不高于简单的胱抑素C公式（P = 0.335）。针对相同临界值的Bland和Altman分析表明，肌酐公式低估了测量的GFR，而简单的胱抑素C公式高估了测量的GFR。所有方程都缺乏precision。根据慢性肾脏病的阶段，估计的（51）Cr - EDTA清除率值在30%范围内的准确性有所不同。对低于和高于45 mL/min/1.73 m²的GFR进行正确预测能力的分析表明，所有公式的预测能力都很高。我们的结果表明，简单的胱抑素C公式仅需要一个变量（血清胱抑素C浓度），是老年人GFR的可靠指标，与包括CKD - EPI公式在内的肌酐公式相当。
