Assessing the diagnostic accuracy of cystatin C as a marker of impaired glomerular filtration rate: In reply

Abstract

We fully agree with Risch and Huber when they state that the diagnostic value of a new marker of impaired glomerular filtration rate (GFR) requires GFR measurements by a reference method and receiver operating characteristic (ROC) analysis together with comparison of areas under the curve (AUC). Keeping in mind these prerequisites, we carefully looked for all the articles dealing with the diagnostic value of serum cystatin C for renal insufficiency (some of them were not published at the time we submitted our article). We found 6 articles evidencing a better diagnostic value for serum cystatin C.1Risch L Blumberg A Huber A Rapid and accurate assessment of glomerular filtration rate in patients with renal transplants using serum cystatin C.Nephrol Dial Transplant. 1999; 14: 1991-1996Crossref PubMed Scopus (118) Google Scholar, 2Kyshe-Andersen J Schmidt C Nordin G Andersson B Nilsson-Ehle P Lindström V Grubb A Serum cystatin C, determined by a rapid, automated particle-enhanced turbidimetric method, is a better marker than serum creatinine for glomerular filtration rate.Clin Chem. 1994; 40: 1921-1926PubMed Google Scholar, 3Randers E Erlandsen EJ Pedersen OL Hasling C Danielsen H Serum cystatin C as an endogenous parameter of the renal function in patients with normal to moderately impaired kidney function.Clin Nephrol. 2000; 54: 203-209PubMed Google Scholar, 4Plebani M Dall'Amico R Mussap M Montini G Ruzzante N Marsilio R Giordano G Zachello G Is serum cystatin C a sensitive marker of glomerular filtration rate (GFR)? A preliminary study on renal transplant patients.Ren Fail. 1998; 20: 303-309Crossref PubMed Scopus (81) Google Scholar, 5Helin I Axenram M Gribb A Serum cystatin C as a determinant of glomerular filtration rate in children.Clin Chem. 1998; 49: 221-225Google Scholar, 6Ylinen EA Ala-Houala M Harmoinen AP Knip M Cystatin C as a marker of glomerular filtration rate in pediatric patients.Ped Nephrol. 1999; 13: 506-509Crossref PubMed Scopus (88) Google Scholar In 6 other publications both parameters had the same diagnostic value,7Oddoze C Morange S Portugal H Berland Y Dussol B Cystatin C is not more sensitive than creatinine for detecting renal impairment in patients with diabetes.Am J Kidney Dis. 2001; 38: 310-316Abstract Full Text PDF PubMed Scopus (104) Google Scholar, 8Chantrel F Agin A Offner M Koehl C Moulin B Hannedouche T Comparison of cystatin C versus creatinine for detection of mild renal failure.Clin Nephrol. 2000; 54: 374-381PubMed Google Scholar, 9Donadio C Lucchesi A Ardini M Giordani R Cystatin C, beta-2-microglobulin, and retinol binding protein as indicators of glomerular filtration rate: Comparison with plasma creatinine.J Pharmaceut Biomed. 2001; 24: 835-842Crossref PubMed Scopus (103) Google Scholar, 10Coll E Botey A Alvarez L Poch E Quinto L Saurina A Vera M Piera C Darnell A Serum cystatin C as a new marker for noninvasive estimation of glomerular filtration rate and as a marker for early renal impairment.Am J Kidney Dis. 2000; 36: 29-34Abstract Full Text Full Text PDF PubMed Scopus (512) Google Scholar, 11Herget-Rosenthal S Trabold S Pietruck F Holtmann M Philipp T Kribben A: Cystatin C Efficacy as screening test for glomerular filtration rate.Am J Nephrol. 2000; 20: 97-102Crossref PubMed Scopus (128) Google Scholar, 12Van Essen GG Stegeman CA Apperloo AJ Rensma PL de Zeeuw D de Jong PE Serum cystatin C is not superior to creatinine-based method to estimate GFR during long term follow up.J Am Soc Nephrol. 1997; 8 (abstr): 79AGoogle Scholar whereas in 3 publications, it was not possible to compare them because of methodological problems (lack of ROC curves or lack of statistical comparison of ROC curves13Seco ML Rus A Sierra M Caballero M Borque L Determination of serum cystatin C in patients with essential hypertension.Nephron. 1999; 81: 446-447Crossref PubMed Google Scholar, 14Fliser D Ritz E Serum cystatin C concentration as a marker of renal dysfunction in the elderly.Am J Kidney Dis. 2001; 37: 79-83Abstract Full Text PDF PubMed Scopus (315) Google Scholar, 15Hayashi T Nitta K Hatano M Nakauchi M Nihei H The serum concentration measured by particle enhanced immunonephelometry is well correlated with inulin clearance in patients with various types of glomerulonephritis.Nephron. 1999; 82: 90-92Crossref PubMed Scopus (31) Google Scholar). Therefore, we believe that even if serum cystatin C is better than creatinine (it is obviously not proven yet), the improvement in the diagnostic accuracy provided by this new parameter does not make it worthy of widespread use.