The article presents the development and validation of a new equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, for estimating glomerular filtration rate (GFR). The CKD-EPI equation was created to address the limitations of the widely used Modification of Diet in Renal Disease (MDRD) Study equation, which has systematic underestimation of GFR at higher values. The CKD-EPI equation includes a spline term for serum creatinine, which allows for a steeper relationship between GFR and creatinine at higher levels, reducing bias. The study involved cross-sectional analysis with separate pooled data sets for equation development and validation, using a representative sample of the U.S. population for prevalence estimates. The CKD-EPI equation performed better than the MDRD Study equation in the validation data set, with less bias, improved precision, and greater accuracy, especially at higher GFRs. The CKD-EPI equation was also more accurate in estimating the prevalence of chronic kidney disease in the National Health and Nutrition Examination Survey (NHANES) data. The authors conclude that the CKD-EPI equation is more accurate than the MDRD Study equation and could replace it for routine clinical use. However, the study has limitations, including a limited sample size of elderly and racial/ethnic minorities. Further research is needed to improve GFR estimation and evaluate alternative markers.The article presents the development and validation of a new equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, for estimating glomerular filtration rate (GFR). The CKD-EPI equation was created to address the limitations of the widely used Modification of Diet in Renal Disease (MDRD) Study equation, which has systematic underestimation of GFR at higher values. The CKD-EPI equation includes a spline term for serum creatinine, which allows for a steeper relationship between GFR and creatinine at higher levels, reducing bias. The study involved cross-sectional analysis with separate pooled data sets for equation development and validation, using a representative sample of the U.S. population for prevalence estimates. The CKD-EPI equation performed better than the MDRD Study equation in the validation data set, with less bias, improved precision, and greater accuracy, especially at higher GFRs. The CKD-EPI equation was also more accurate in estimating the prevalence of chronic kidney disease in the National Health and Nutrition Examination Survey (NHANES) data. The authors conclude that the CKD-EPI equation is more accurate than the MDRD Study equation and could replace it for routine clinical use. However, the study has limitations, including a limited sample size of elderly and racial/ethnic minorities. Further research is needed to improve GFR estimation and evaluate alternative markers.