Does cystatin C improve the precision of Cockcroft and Gault's creatinine clearance estimation?

J Nephrol. 2004 Sep-Oct;17(5):673-8.


Background: Cystatin C is increasingly used to estimate renal function, but its large intraindividual variability limits its practical value. This study aimed at verifying whether the clinical practice of associating cystatin C determination with serum creatinine (Cr) improved the ability of the Cockcroft and Gault formula to estimate creatinine clearance (CrCl).

Methods: It was an observational cross-sectional study of 134 in-patients with mildly impaired renal function. Using the Hoek et al formula (glomerular filtration rate (GFR)/1.73m2 = - 4.32 + 80.35/cystatin C mg/L), multivariate linear regressions (LREG) and artificial neural networks (ANN), we integrated cystatin C in the Cockcroft and Gault formula and analyzed the potential superiority of this procedure by comparing its performance with that of the two algorithms taken separately.

Results: The inclusion of cystatin C in the Cockcroft and Gault formula using the data of an LREG (CrCl = 0.371 x (Hoek et al) + 0.589 x Cockcroft and Gault), a simple mean between the two algorithms or ANN ameliorated the CrCl estimation precision allowing an absolute error reduction of approximately 4, 4 and 6%, respectively (relative values 12, 12 and 17%).

Conclusions: Although the combination of the Hoek et al and Cockcroft and Gault formulae using both linear and non-linear mathematical methods allowed a statistically significant reduction in the estimation error generated by Cockcroft and Gault, considering the small impact on the estimation precision and the large intraindividual variation of both cystatin C and Cr, this procedure probably has no clinical relevance.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Algorithms*
  • Creatinine / blood*
  • Creatinine / urine*
  • Cross-Sectional Studies
  • Cystatin C
  • Cystatins / blood*
  • Female
  • Glomerular Filtration Rate*
  • Humans
  • Kidney Diseases / blood
  • Kidney Diseases / diagnosis*
  • Kidney Diseases / urine
  • Linear Models
  • Male
  • Middle Aged
  • Neural Networks, Computer
  • Reproducibility of Results


  • CST3 protein, human
  • Cystatin C
  • Cystatins
  • Creatinine