Comparison of two methods for the calculation of estimated glomerular filtration rate.

Background: Due to limitations of reference methods, it is recommended to estimate glomerular filtration rate (GFR) by serum creatinine-based equations. The purpose of this study was to assess the correlation between the Modification of Diet in Renal Disease (MDRD) formula and the new "Mayo Clinic Quadratic" (MCQ) equation. Methods: Cumulative results for serum creatinine were retrospectively analyzed in 8,388 outpatients. Results: A significant correlation was observed between the MDRD and MCQ estimates; however, a greater disparity of values, and a less satisfactory correlation, was observed between the 2 equations in subjects with MDRD estimates of GFR >60 mL/min per 1.73 m2. The prevalence of subjects with abnormal GFR values was also significantly different when calculated with either formula. Conclusion: Our results support the hypothesis the new MCQ equation may be a step toward accurately estimating GFR when the diagnosis of chronic kidney disease is unknown.