Original Paper

A Comparison of Prediction Equations for Estimating Glomerular Filtration Rate in Adult Patients with Chronic Kidney Disease Stages 4-5
Effect of Nutritional Status and Age
Néstor Fontseré^a, Jordi Bonal^a, Maru Navarro^a, Joaquim Riba^b, Manel Fraile^b, Ferran Torres^c, Ramón Romero^a

Departments of
^aNephrology and
^bNuclear Medicine, University Hospital Germans Trias i Pujol, Badalona, and
^cBiostatistics and Epidemiology Laboratory, Universidad Autónoma de Barcelona, Barcelona, Spain

Address of Corresponding Author

Nephron Clin Pract 2006;104:c160-c168 (DOI: 10.1159/000095476)

  Key Words

• Prediction equations
• Glomerular filtration rate
• Chronic kidney disease stages 4-5
• Lower creatinine production

  Abstract

Background: The accuracy of prediction equations has not been validated in adult patients with chronic kidney disease (CKD) stages 4-5 in extreme situations of nutritional status and age. Objective and Methods: The significance of nutritional status, calculated with the creatinine production (CP) formula, and age (64 years and >64 years) in the application of different prediction equations - modification of diet in renal disease (MDRD), simplified MDRD (sMDRD), Cockcroft-Gault (CG) - and the mean of urea and creatinine clearance (Cr-Ur) compared with the isotopic glomerular filtration rate (GFR) estimation calculated by 51Cr-EDTA was studied in 87 Caucasian adults with CKD stages 4-5 (GFR: 30-8 ml/min/1.73 m²). The Bland-Altman method and Lin's concordance coefficient (Rc) were used to study accuracy (bias) and precision. Results: The GFR calculated with ⁵¹Cr-EDTA in the study group was 22.2 ± 6.9 ml/min/1.73 m² (range: 8-30). CG and sMDRD were the best prediction equations with bias of -1.1 and -3.8 ml/min/1.73 m² and Rc of 0.52-0.50. In this situation, the mean Cr-Ur proved the most inaccurate equation compared with the isotopic technique with bias of -5.4 ml/min/1.73 m² and Rc of 0.32. In the analysis of patients with higher CP (> 0.90; n = 44), CG and sMDRD obtained the best bias of 1.2 and -2.7 ml/min/1.73 m² and Rc of 0.54-0.53. In patients aged 64 (n = 44), these equations obtained a bias of 1.1 and -3.6 ml/min/1.73 m² and Rc 0.50-0.49. Both in lower CP (0.90; n = 43) and older age (>64 years; n = 43), all the equations underestimated the value obtained with isotopic GFR. In these situations, the results obtained with CG had a bias of -2.2 and -3.6 ml/min/1.73 m² (Rc 0.29-0.56) and with sMDRD -4.0 and -4.1 ml/min/1.73 m² (Rc 0.39-0.51). In these circumstances, Cr-Ur was the most inaccurate equation, obtaining a bias of -10.1 and -13.2 ml/min/1.73 m² (Rc 0.14-0.16). Conclusions: In the group with higher CP and age 64 years, results of the presented data yielded no evidence for superiority of the MDRD equation over CG formula in patients with advanced renal failure. On the basis of our results, we do not recommend the use of the Cr-Ur adjusted to 1.73 m² of body surface area, which was the most imprecise equation. Application of all the equations proved inaccurate in lower CP patients with or without advanced age, implying the premature start of substitution renal treatment. In these circumstances, ambulatory GFR determination by isotopic techniques would be indicated.

Copyright © 2006 S. Karger AG, Basel

  Author Contacts

Néstor Fontseré Baldellou
Nephrology Department, Hospital de Terrassa
Carretera Torrebonica s/n
ES-08227 Terrassa (Spain)
Tel. +34 93 731 0007, Fax +34 93 731 0959, E-Mail 34989nfb@comb.es

  Article Information

Received: December 15, 2005
Accepted: May 31, 2006
Published online: August 30, 2006
Number of Print Pages : 9
Number of Figures : 3, Number of Tables : 2, Number of References : 21