Stevens Lesley A, Manzi Jane, Levey Andrew S, Chen Jing, Deysher Amy E, Greene Tom, Poggio Emilio D, Schmid Christopher H, Steffes Michael W, Zhang Yaping Lucy, Van Lente Frederick, Coresh Josef
Division of Nephrology, Tufts-New England Medical Center, 750 Washington St, Box #391, Boston, MA 02111, USA.
Am J Kidney Dis. 2007 Jul;50(1):21-35. doi: 10.1053/j.ajkd.2007.04.004.
Variation in performance of glomerular filtration rate (GFR) estimating equations is related to variation in calibration of the creatinine assay across clinical laboratories.
Cross-sectional analysis.
SETTING & PARTICIPANTS: 6 research studies and 4 clinical populations including 5,504 participants who had GFR measured using urinary clearance of iothalamate.
Standardized serum creatinine values obtained by means of calibration to the Cleveland Clinic Research Laboratory using frozen specimens, a calibration panel, and/or survey results from the College of American Pathologists.
Noncalibrated serum creatinine assayed in research and clinical laboratories compared with standardized serum creatinine.
Difference between measured GFR versus GFR estimated from the Modification of Diet in Renal Disease (MDRD) Study and Cockcroft-Gault equations.
For a noncalibrated serum creatinine value of 1 mg/dL (88.4 micromol/L), standardized serum creatinine value was 0.07 mg/dL (6.2 micromol/L) less than noncalibrated values. In the pooled data set, for the MDRD Study equation, calibration improved median percentage of difference between measured and estimated GFR from 9.0% (interquartile range [IQR], 28%) to 5.8% (IQR, 28%) and improved the percentage of estimates within 30% of measured GFR (P30) from 80% to 83%. The effect of calibration was greater at higher levels of GFR and varied across studies. For the Cockcroft-Gault equation, calibration worsened the median percentage of difference from -2.0% (IQR, 38%) to -11.4% (IQR, 39%), and the P30, from 74% to 69%.
College of American Pathologist samples were used for calibration of clinical populations; calibration factors do not account for drift over time in the serum creatinine assay; calibration cannot account for variation in assay performance among individuals.
Calibration improves the performance of the MDRD Study equation. After calibration, larger errors remain for GFR estimates greater than 60 mL/min/1.73 m2 (>1 mL/s/1.73 m2).
肾小球滤过率（GFR）估算方程的性能差异与各临床实验室中肌酐检测方法校准的差异相关。
横断面分析。
6项研究及4个临床群体，共5504名参与者，其GFR通过碘他拉酸盐的尿清除率进行测量。
通过使用冷冻标本、校准板和/或美国病理学家学会的调查结果，将血清肌酐值校准至克利夫兰诊所研究实验室所获得的标准化血清肌酐值。
研究和临床实验室中未经校准的血清肌酐与标准化血清肌酐的比较。
对于未经校准的血清肌酐值1mg/dL（88.4μmol/L），标准化血清肌酐值比未经校准的值低0.07mg/dL（6.2μmol/L）。在汇总数据集中，对于肾脏病饮食改良（MDRD）研究方程，校准后测量的GFR与估算的GFR之间差异的中位数百分比从9.0%（四分位间距[IQR]，28%）改善至5.8%（IQR，28%），且估算值在测量GFR的30%范围内（P30）的百分比从80%提高至83%。在校准后的GFR水平较高时，校准的效果更显著，且各研究之间存在差异。对于Cockcroft-Gault方程，校准使差异的中位数百分比从-2.0%（IQR，38%）恶化至-11.4%（IQR，39%），P30从74%降至69%。
美国病理学家学会的样本用于临床群体的校准；校准因子未考虑血清肌酐检测方法随时间的漂移；校准无法解释个体间检测性能的差异。
校准可改善MDRD研究方程的性能。校准后，对于GFR估算值大于60mL/min/1.73m²（>1mL/s/1.73m²）的情况，仍存在较大误差。
