European Heart Journal Advance Access originally published online on October 16, 2007
European Heart Journal 2007 28(22):2818-2819; doi:10.1093/eurheartj/ehm433
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Cystatin C blood level as a risk factor for death after heart surgery: reply
Intensive Care Unit
Liège University Hospital
Sart Tilman Bat B35
B-4000 Liège
Belgium
Intensive Care Unit
Institut Jacques Cartier
Massy
France
Department of Clinical Chemistry
Liège University Hospital
Sart Tilman Bat B35
B-4000 Liège
Belgium
Intensive Care Unit
Liège University Hospital
Sart Tilman Bat B35
B-4000 Liège
Belgium
Tel: +32 4366 7494 fax: +32 4366 8898 E-mail address: dledoux{at}chu.ulg.ac.be
We thank Dr Lambermont et al. for their comments on the GFR estimation from the serum cystatin C level. The issue raised by these authors is indeed of some interest. However, we think that they did not focus on the right problem. It is correct that, as for serum creatinine measurement, different methods exist for the measurement of serum Cystatin C. However it has been shown that agreement between particle enhanced nephelometric immunoassay (PENIA) and particle enhanced turbidimetric immunoassay (PETIA) methods is good.1 There are to date at least 10 published equations for GFR estimation from cystatin C. These equations lead to GFR estimations that vary not only according to the used assay. As other authors already pointed,2 we think that the discrepancy (Table 1) between these published equations is due, for a large part, to the patients casemix differences, to the use of different gold standard measurements for GFR and to the small sample size of these studies. Therefore one should rather stress the need for the construction of a proper cystatin C based GFR equation relying on a large patient cohort as it was the case for the creatinine based MDRD GFR equation.3
|
The formula we chose for GFR calculation from cystatin C was the indeed based PETIA serum cystatin C assay.4 However it was the only study dealing with a relatively large sample of adult patients with a high proportion of healthy persons and we expected that this casemix would be more comparable to ours. On the contrary, the equation proposed by Lambermont et al. refers to a casemix of patients with known chronic kidney disease (CKD), which was not the case for the majority of our patients.
We nevertheless performed the logistic and the Cox models with 10 published equations2 and found results similar to those published in our manuscript.5 We found that, using the method described in our manuscript for the multivariable analysis, the models selected the EuroSCORE and the GFR estimated from serum Cystatin C with similar odds ratio, confidence intervals and P-values and this regardless the formula used for the GFR estimation. It appears that the results we observed are not particularly sensitive to which formula is used for the estimation of the GFR from serum cystatin C. The conclusions of our work remain therefore valid.
References
- Finney H, Newman DJ, Gruber W, Merle P, Price CP. Initial evaluation of cystatin C measurement by particle-enhanced immunonephelometry on the Behring nephelometer systems (BNA, BN II). Clin Chem (1997) 43(Pt 1):1016–1022.
[Abstract/Free Full Text] - Herget-Rosenthal S, Bokenkamp A, Hofmann W. How to estimate GFR-serum creatinine, serum cystatin C or equations? Clin Biochem (2007) 40:153–161.[CrossRef][Web of Science][Medline]
- Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of diet in renal disease study group. Ann Intern Med (1999) 130:461–470.
[Abstract/Free Full Text] - Grubb A, Nyman U, Bjork J, Lindstrom V, Rippe B, Sterner G, Christensson A. Simple Cystatin C-based prediction equations for glomerular filtration rate compared with the modification of diet in renal disease prediction equation for adults and the Schwartz and the Counahan–Barratt prediction equations for children. Clin Chem (2005) 51:1420–1431.
[Abstract/Free Full Text] - Ledoux D, Monchi M, Chapelle JP, Damas P. Cystatin C blood level as a risk factor for death after heart surgery. Eur Heart J (2007) 28:1848–1853.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||