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 more accurate than CG. In healthy patients, in subjects with normal SCr and in elderly patients, MDRD was not superior. Based on the risk of misclassifying by ≥2 CKD stages, neither formula could be safely applied in diabetic, low body mass index, advanced liver disease, chronic heart failure, or hospitalized patients.

Conclusions: CG still has an interest in screening the decline in renal function in subjects with normal SCr who are at risk, such as diabetics and stage 1 and 2 CKD patients, as well as healthy subjects enrolled in clinical trials and pharmacokinetic studies. Thus, it may be early to replace CG by MDRD in drug studies. CG still is the better formula in the elderly. Both formulas are not safe in some populations.