Should We Continue to Use the Cockcroft-Gault Formula?

Background/Aims: Although the National Kidney Disease Education Program recommends use of the modification of diet in renal disease (MDRD) formula to estimate the glomerular filtration rate (GFR), most drug-dosing recommendations and clinical practices employ the Cockcroft-Gault (CG) formula. The quality score of the original MDRD study was better than that of the original CG study, although the imprecision sources were very similar between the formulas. To address whether CG should be abandoned in favour of MDRD in chronic kidney disease (CKD) management, we performed a literature review on the topic. Methods: We reviewed 27 articles comparing CG and MDRD in terms of bias, precision, accuracy, and the risk of misclassifying by two CKD stages. Results: In the chronic renal disease population, MDRD was more precise, safer and more accurate than CG at predicting the GFR, with two exceptions: CG was clearly superior in CKD patients with a normal serum creatinine (SCr) and results were discordant in patients with advanced renal failure. In diabetic populations with normal and near-normal GFR, the decline in renal function in diabetics was better screened by CG. In diabetics with renal impairment, MDRD is Published online: July 2, 2010 Dr. Rafik Helou, MD Department of Internal Medicine, Bertinot Juel Hospital 34 bis rue Pierre Budin FR–60240 Chaumont en Vexin (France) Fax +33 344 495 456, E-Mail heloumail @ yahoo.com © 2010 S. Karger AG, Basel 1660–2110/10/1163–0172$26.00/0 Accessible online at: www.karger.com/nec MDRD versus Cockcroft-Gault Formula for GFR Estimation Nephron Clin Pract 2010;116:c172–c186 c173 Cockcroft and Gault derived their equation from a population of 236 male hospitalized patients who had 2 CrCl determinations that differed by ! 20%. The mean of 2 CrCl determinations were used to derive the formula, considering age and patient weight. A 15% reduction was recommended when applying the formula to women. Although the original purpose of the formula was to estimate CrCl, CG was later proposed to directly predict GFR [7] . In contrast, the 4-variable MDRD resulted from a retrospective multicentre controlled trial of the effects of dietary protein restriction and strict blood pressure control on kidney disease progression. The MDRD takes into account serum creatinine (SCr), age, gender and race. The major weakness of the original CG study has been the non-separation between the training and validation samples. When comparing the quality of the original CGand MDRD-deriving studies overall, the MDRD study clearly prevails (Appendix 1, table 1 ). However, this is of secondary importance if the CG formula performs at least comparably to the MDRD formula. Considering the success of the MDRD, the main goal of the present review was to determine whether the CG formula should be abandoned or if it still has a place in renal function analysis. In the original MDRD study, several subgroups were excluded or insufficiently represented, including the elderly, diabetics, patients with end-stage renal disease or Table 1. a Comparison of the patient characteristics and methodologies used in deriving the CG and MDRD formulas