Fontseré Néstor, Salinas Isabel, Bonal Jordi, Bayés Beatriz, Riba Joaquim, Torres Ferran, Rios Jose, Sanmartí Ana, Romero Ramón
Department of Nephrology, Hospital de Terrassa, Ctra Torrebonica s/n, 08227, Terrassa, Barcelona, Spain.
Nephrol Dial Transplant. 2006 Aug;21(8):2152-8. doi: 10.1093/ndt/gfl221. Epub 2006 May 15.
The aim of this study was to compare the accuracy of prediction equations [modification of diet in renal disease (MDRD), simplified MDRD, Cockcroft-Gault (CG), reciprocal of creatinine and creatinine clearance] in a cohort of patients with type 2 diabetes.
A total of 525 glomerular filtration rates (GFRs) using (125)I-iothalamate were carried out over 10 years in 87 type 2 diabetic patients. Accuracy was evaluated at three levels of renal function according to the baseline values obtained with the isotopic method: hyperfiltration (GFR: >140 ml/min/1.73 m(2); 140 isotopic determinations in 27 patients), normal renal function (GFR: 140-90 ml/min/1.73 m(2); 294 isotopic determinations in 47 patients) and chronic kidney disease (CKD) stages 2-3 (GFR: 30-89 ml/min/1.73 m(2); 87 isotopic determinations in 13 patients). The annual slope for GFR (change in GFR expressed as ml/min/year) was considered to ascertain the variability in the equations compared with the isotopic method during follow-up. Student's t-test was used to determine the existence of significant differences between prediction equations and the isotopic method (P < 0.05 with Bonferroni adjusted for five contrast tests).
In the subgroup of patients with hyperfiltration, a GFR slope calculated with (125)I-iothalamate -4.8 +/- 4.7 ml/min/year was obtained. GFR slope in patients with normal renal function was -3.0 +/- 2.3 ml/min/year. In both situations, all equations presented a significant underestimation compared with the isotopic GFR (P < 0.01; P < 0.05). In the subgroup of CKD stages 2-3, the slope for GFR with (125)I-iothalamate was -1.4 +/- 1.8 ml/min/year. The best prediction equation compared with the isotopic method proved to be MDRD with a slope for GFR of -1.4 +/- 1.3 ml/min/year (P: NS) compared with the CG formula -1.0 +/- 0.9 ml/min/year (P: NS). Creatinine clearance presented the greatest variability in estimation (P < 0.001).
In the normal renal function and hyperfiltration groups, none of the prediction equations demonstrated acceptable accuracy owing to excessive underestimation of renal function. In CKD stages 2-3, with mean serum creatinine > or =133 micromol/l (1.5 mg/dl), the MDRD equation can be used to estimate GFR during the monitoring and follow-up of patients with type 2 diabetes receiving insulin, anti-diabetic drugs or both.
本研究旨在比较预测方程[肾脏病饮食改良（MDRD）方程、简化MDRD方程、Cockcroft - Gault（CG）方程、肌酐倒数法和肌酐清除率法]在2型糖尿病患者队列中的准确性。
在87例2型糖尿病患者中，历时10年共进行了525次使用（125）I - 碘肽酸盐的肾小球滤过率（GFR）测定。根据同位素法获得的基线值，在三个肾功能水平评估准确性：超滤（GFR：>140 ml/min/1.73 m²；27例患者中有140次同位素测定）、肾功能正常（GFR：140 - 90 ml/min/1.73 m²；47例患者中有294次同位素测定）以及慢性肾脏病（CKD）2 - 3期（GFR：30 - 89 ml/min/1.73 m²；13例患者中有87次同位素测定）。GFR的年斜率（以ml/min/年表示的GFR变化）用于确定随访期间与同位素法相比各方程的变异性。采用Student t检验确定预测方程与同位素法之间是否存在显著差异（经Bonferroni校正用于五次对比检验，P < 0.05）。
在超滤亚组中，用（125）I - 碘肽酸盐计算得出的GFR斜率为 - 4.8 ± 4.7 ml/min/年。肾功能正常患者的GFR斜率为 - 3.0 ± 2.3 ml/min/年。在这两种情况下，与同位素GFR相比，所有方程均出现显著低估（P < 0.01；P < 0.05）。在CKD 2 - 3期亚组中，（125）I - 碘肽酸盐测定的GFR斜率为 - 1.4 ± 1.8 ml/min/年。与同位素法相比，最佳预测方程为MDRD方程，其GFR斜率为 - 1.4 ± 1.3 ml/min/年（P：无显著差异），而CG公式的GFR斜率为 - 1.0 ± 0.9 ml/min/年（P：无显著差异）。肌酐清除率在估计中表现出最大的变异性（P < 0.001）。
在肾功能正常和超滤组中，由于对肾功能的过度低估，没有一个预测方程显示出可接受的准确性。在CKD 2 - 3期，平均血清肌酐≥133 μmol/l（1.5 mg/dl）时，MDRD方程可用于在接受胰岛素、抗糖尿病药物或两者的2型糖尿病患者的监测和随访期间估计GFR。
