Presented in part at the Symposium Celebrating the 40th Anniversary of Chronic Dialysis and Kidney Transplantation in Slovenia held 4–5 November 2010 in Bled, Slovenia.
Simple Cystatin C Formula Compared to Sophisticated CKD-EPI Formulas for Estimation of Glomerular Filtration Rate in the Elderly
Article first published online: 30 MAY 2011
© 2011 The Authors. Therapeutic Apheresis and Dialysis © 2011 International Society for Apheresis
Therapeutic Apheresis and Dialysis
Volume 15, Issue 3, pages 261–268, June 2011
How to Cite
Bevc, S., Hojs, R., Ekart, R., Gorenjak, M. and Puklavec, L. (2011), Simple Cystatin C Formula Compared to Sophisticated CKD-EPI Formulas for Estimation of Glomerular Filtration Rate in the Elderly. Therapeutic Apheresis and Dialysis, 15: 261–268. doi: 10.1111/j.1744-9987.2011.00948.x
Conflict of interest statement: None declared.
- Issue published online: 30 MAY 2011
- Article first published online: 30 MAY 2011
- Received March 2011.
- 51Cr-EDTA clearance;
- Chronic kidney disease;
- Glomerular filtration rate;
- Serum creatinine-based equation;
- Serum cystatin C-based equation
Despite the fact that the serum creatinine level is notoriously unreliable for the estimation of glomerular filtration rate (GFR) in the elderly, the serum creatinine concentration and serum creatinine-based formulas, such as the Modification of Diet in Renal Disease study equation (MDRD) are the most commonly used markers to estimate GFR. Recently, serum cystatin C-based formulas, the newer creatinine formula (the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI creatinine formula), and an equation that uses both serum creatinine and cystatin C (CKD-EPI creatinine and cystatin formula) were proposed as new GFR markers. The aim of our study was to compare the MDRD formula, CKD-EPI creatinine formula, CKD-EPI creatinine and cystatin formula, and simple cystatin C formula (100/serum cystatin C) against 51Cr-EDTA clearance in the elderly. A total of 317 adult Caucasian patients aged >65 years were enrolled. In each patient, 51Cr-EDTA clearance, serum creatinine, and serum cystatin C were determined, and the GFR was calculated using the MDRD formula, CKD-EPI formulas, and simple cystatin C formula. Statistically significant correlations between 51Cr-EDTA clearance and all formulas were found. In the receiver operating characteristic (ROC) curve analysis with a cut-off of GFR 45 mL/min/1.73 m2, a higher diagnostic accuracy was achieved with the equation that uses both serum creatinine and cystatin C (CKD-EPI creatinine and cystatin formula) than the MDRD formula (P < 0.013) or CKD-EPI creatinine formula (P < 0.01), but it was not higher than that achieved for the simple cystatin C formula (P = 0.335). Bland and Altman analysis for the same cut-off value showed that the creatinine formulas underestimated and the simple cystatin C formula overestimated measured GFR. All equations lacked precision. The accuracy within 30% of estimated 51Cr-EDTA clearance values differ according to the stage of CKD. Analysis of the ability to correctly predict GFR below and above 45 mL/min/1.73 m2 showed a high prediction for all formulas. Our results indicate that the simple cystatin C formula, which requires just one variable (serum cystatin C concentration), is a reliable marker of GFR in the elderly and comparable to the creatinine formulas, including the CKD-EPI formulas.