Comparison of the usefulness of selected formulas for GFR estimation in patients with diagnosed chronic kidney disease

Abstract

Introduction: The diagnosis and classification of chronic kidney disease (CKD) are based on the glomerular filtration rate value. The simplest way to evaluate glomerular filtration rate is to estimate it based on serum creatinine concentration using one of many specific mathematical formulas. None of the formulas created for this purpose are perfect. Differences in eGFR values are frequently observed in specific stages of chronic kidney disease by KDIGO classification based on different formulas. Aim: The aim of the study is to compare the eGFR value in patients previously diagnosed with CKD treated in the Outpatient Nephrology Unit of the University Hospital in Krakow using the selected formulas. Material/Methods: The study was performed in a group of 882 patients (392 women, 490 men) aged 65.0 ± 14.8 years. GFR values were estimated using Bjornsson, the abbreviated MDRD, and CKD-EPI formulas. These values were then compared according to chronic kidney disease stage and age groups: above and below 60 years. Results: The mean eGFR value was for Bjornsson formula- 47.2 ± 21.1 ml/min/1.73m2, abbreviated MDRD formula- 38.8 ± 15.2 ml/min/1.73m2, and CKD-EPI formula- 37.7 ± 15.9 ml/min/1.73m2. There was a large concordance in eGFR values obtained using the CKD-EPI and abbreviated MDRD formulas in every stage of chronic kidney disease and in both age groups. The Bjornsson formula significantly increased the number of patients in early stages of CKD, G1 - 33 vs 2 (abbreviated MDRD) and 6 (CKD-EPI), G2- 186 vs 70 (abbreviated MDRD) and 69 (CKD-EPI). Conclusions: CKD-EPI and abbreviated MDRD formulas have a similar usefulness in GFR value estimation in patients with diagnosed chronic kidney disease. Lower eGFR values achieved using abbreviated MDRD formula and CKD-EPI equation in comparison with Bjornsson’s formula may result in an increased number of patients diagnosed with CKD.