BACKGROUND: The performance of the Cockcroft-Gault (CG) equation, the Modification of Diet in Renal Disease (MDRD) formula, and the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) was evaluated in body mass index (BMI) categories. MATERIAL AND METHODS: In this retrospective cohort study in diabetic patients, creatinine clearance was measured by collecting 24-hour urines. Renal function was estimated using the CG, MDRD, and CKD-EPI. The performance of the equations was evaluated using correlation, Krippendorff's coefficient, bias, precision, and accuracy. RESULTS: The bias of the MDRD and CKD-EPI increased from -13.9 ml/min/1.73 m(2) and -14.0 ml/min/1.73 m(2) (BMI < 25 kg/m(2)), respectively, to -31.7 ml/min/1.73 m(2) and -29.6 ml/min/1.73 m(2) (BMI > 30 kg/m(2)), respectively. Bias of the CG decreased from -13.4 ml/min (BMI < 25 kg/m(2)) to -3.2 ml/min (BMI > 30 kg/m(2)). With an accepted 30% dispersion, CG had the largest accuracy in the overweight and obese group (76.9 and 76.8%, respectively). The MDRD and CKD-EPI had an accuracy of 45.8 and 34.0% (overweight group), respectively,and 51.9 and 37.3% (obese group), respectively. CONCLUSIONS: All renal function prediction equations are biased when used in overweight or obese diabetic populations with preserved renal function. The CG provides the best estimate of kidney function. The limitations of renal function prediction equations should be kept in mind when making clinical decisions.
BACKGROUND: The performance of the Cockcroft-Gault (CG) equation, the Modification of Diet in Renal Disease (MDRD) formula, and the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) was evaluated in body mass index (BMI) categories. MATERIAL AND METHODS: In this retrospective cohort study in diabeticpatients, creatinine clearance was measured by collecting 24-hour urines. Renal function was estimated using the CG, MDRD, and CKD-EPI. The performance of the equations was evaluated using correlation, Krippendorff's coefficient, bias, precision, and accuracy. RESULTS: The bias of the MDRD and CKD-EPI increased from -13.9 ml/min/1.73 m(2) and -14.0 ml/min/1.73 m(2) (BMI < 25 kg/m(2)), respectively, to -31.7 ml/min/1.73 m(2) and -29.6 ml/min/1.73 m(2) (BMI > 30 kg/m(2)), respectively. Bias of the CG decreased from -13.4 ml/min (BMI < 25 kg/m(2)) to -3.2 ml/min (BMI > 30 kg/m(2)). With an accepted 30% dispersion, CG had the largest accuracy in the overweight and obese group (76.9 and 76.8%, respectively). The MDRD and CKD-EPI had an accuracy of 45.8 and 34.0% (overweight group), respectively,and 51.9 and 37.3% (obese group), respectively. CONCLUSIONS: All renal function prediction equations are biased when used in overweight or obese diabetic populations with preserved renal function. The CG provides the best estimate of kidney function. The limitations of renal function prediction equations should be kept in mind when making clinical decisions.
Authors: Jan C van Blijderveen; Sabine M Straus; Robert Zietse; Bruno H Stricker; Miriam C Sturkenboom; Katia M Verhamme Journal: Int Urol Nephrol Date: 2013-09-27 Impact factor: 2.370