title: Multicenter study of creatinine- and/or cystatin C-based equations for estimation of glomerular filtration rates in Chinese patients with chronic kidney disease.
abstract: OBJECTIVE
  To establish equations for the estimation of glomerular filtration rates (eGFRs) based on serum creatinine (SCr) and/or serum cystatin C (SCysC) in Chinese patients with chronic kidney disease (CKD), and to compare the new equations with both the reference GFR (rGFR) and the literature equations to evaluate their applicability.
  
  
  METHODS
  The 788 Chinese CKD patients were randomly divided into two groups, the training group and the testing group, to establish new eGFR-formulas based on serum CysC and to validate the established formulas, respectively. (99m)Tc-DTPA clearance (as the rGFR), serum Cr, and serum CysC were determined for all patients, and GFR was calculated using the Cockcroft-Gault equation (eGFR1), the MDRD formula (eGFR2), the CKD-EPI formulas (eGFR3, eGFR4), and the Chinese eGFR Investigation Collaboration formulas (eGFR5, eGFR6). The accuracy of each eGFR was compared with the rGFR.
  
  
  RESULTS
  The training and testing groups' mean GFRs were 50.84±31.36 mL/min/1.73 m(2) and 54.16±29.45 mL/min/1.73 m(2), respectively. The two newly developed eGFR formulas were fitted using iterative computation: [Formula: see text] and [Formula: see text]. Significant correlation was observed between each eGFR and the rGFR. However, proportional errors and constant errors were observed between rGFR and eGFR1, eGFR2, eGFR4, eGFR5 or eGFR6, and constant errors were observed between eGFR3 and rGFR, as revealed by the Passing & Bablok plot analysis. The Bland-Altman analysis illustrated that the 95% limits of agreement of all equations exceeded the previously accepted limits of <60 mL/min •1.73 m(2), except the equations of eGFR7 and eGFR8.
  
  
  CONCLUSIONS
  The newly developed formulas, eGFR7 and eGFR8, provide precise and accurate GFR estimation using serum CysC detection alone or in combination with serum Cr detection. Differences in detection methods should be carefully considered when choosing literature eGFR equations to avoid misdiagnosis and mistreatment.
authors.affiliation: Laboratory Medicine, Mianyang Central Hospital, Mianyang, Sichuan Province, China. jiafufeng@yahoo.com.cn
authors.forename: Jia-fu
authors.initials: JF
authors.lastname: Feng
authors.forename: Ling
authors.initials: L
authors.lastname: Qiu
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Xue-mei
authors.initials: XM
authors.lastname: Li
authors.forename: Yu-wei
authors.initials: YW
authors.lastname: Yang
authors.forename: Ping
authors.initials: P
authors.lastname: Zeng
authors.forename: Xiu-zhi
authors.initials: XZ
authors.lastname: Guo
authors.forename: Yan
authors.initials: Y
authors.lastname: Qin
authors.forename: Hong-chun
authors.initials: HC
authors.lastname: Liu
authors.forename: Xing-min
authors.initials: XM
authors.lastname: Han
authors.forename: Yan-peng
authors.initials: YP
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Shu-yan
authors.initials: SY
authors.lastname: Sun
authors.forename: Li-qiang
authors.initials: LQ
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Quan
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Xia
authors.forename: Hong-zhang
authors.initials: HZ
authors.lastname: Hu
authors.forename: Fang-cai
authors.initials: FC
authors.lastname: Zhong
authors.forename: Rong
authors.initials: R
authors.lastname: Duan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis*; D055815:Young Adult
chemical_list: C525030:CST3 protein, human; D055316:Cystatin C; D003404:Creatinine