Predictable impact of the routine implementation of the CKD-EPI eqyation for estimating glomerular filtration rate by a simulation study

Background Chronic kidney disease (CKD) is a major public health problem worldwide. According to available guidelines, the estimated glomerular filtration rate (GFR) should be reported by hospital and commercial laboratories preferentially using the Modification of Diet in Renal Disease (MDRD) study equation. Although the clinical performance of the newer Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation has been assessed against directly measured GFR, the correlation between this new equation and the MDRD equation and the Cockcroft-Gault (C-G) equation, which is largely used for estimating GFR by general practitioners and hospital physicians, has not been fully evaluated. Methods We automatically generated 14 classes of serum creatinine values (from 0.7 to 2.0 mg/dl in increments of 0.1 mg/dl) each containing 68 classes of age (from 18 to 85 years in increments of 1 year) and 46 classes of body weight (from 40 to kg in increments of 1 kg), for both genders. In each case, GFR was estimated with the C-G, MDRD and CKD-EPI equations. Results The data generation procedure resulted in 87,584 different virtual cases representing Caucasians. The median estimated GFR values generated with each of the three equations were 56.4, 56.8 and 60.7 ml/min/1.73 m2 for the C-G, MDRD and CKD-EPI equations, respectively, in men (all p<0.001), and 47.9, 42.2 and 45.8 ml/min/1.73 m2 for the C-G, MDRD and CKD-EPI equations, respectively, in women (all p<0.001). The overall correlation between the CKD-EPI and C-G equations was marginally better than that between the MDRD and C-G equations (i.e. 0.844 versus 0.811 in men and 0.842 versus 0.811 in women), and the overall diagnostic performance (AUC 0.91 versus 0.89 in men and 0.93 versus 0.91 in women; both p<0.001) were also in favour of the CKD-EPI. The good agreement with the data obtained with the previous MDRD equation (i.e. kappa 0.89 in men and 0.86 in women) also confirms that replacing one equation with another would not generate a substantial change in laboratory-related risk assessment or patient classification according to the GFR values. Conclusions With careful consideration of the inherent drawbacks of serum creatinine for assessing GFR, but due to a good correlation with the reference method and a better correlation with the C-G equation than with the former MDRD equation, we suggest that the novel CKD-EPI equation might be appropriate to use in laboratory reports for reporting the estimated GFR.