title: Is the Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin C equation useful for glomerular filtration rate estimation in the elderly?
abstract: BACKGROUND
  We aimed to evaluate the performance of the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-cystatin C equation in a cohort of elderly Chinese participants.
  
  
  METHODS
  Glomerular filtration rate (GFR) was measured in 431 elderly Chinese participants by the technetium-99m diethylene-triamine-penta-acetic acid ((99m)Tc-DTPA) renal dynamic imaging method, and was calibrated equally to the dual plasma sample (99m)Tc-DTPA-GFR. Performance of the CKD-EPI creatinine-cystatin C equation was compared with the Cockcroft-Gault equation, the re-expressed 4-variable Modification of Diet in Renal Disease (MDRD) equation, and the CKD-EPI creatinine equation.
  
  
  RESULTS
  Although the bias of the CKD-EPI creatinine-cystatin C equation was greater than with the other equations (median difference, 5.7 mL/minute/1.73 m(2) versus a range from 0.4-2.5 mL/minute/1.73 m(2); P<0.001 for all), the precision was improved with the CKD-EPI creatinine-cystatin C equation (interquartile range for the difference, 19.5 mL/minute/1.73 m(2) versus a range from 23.0-23.6 mL/minute/1.73 m(2); P<0.001 for all comparisons), leading to slight improvement in accuracy (median absolute difference, 10.5 mL/minute/1.73 m(2) versus 12.2 and 11.4 mL/minute/1.73 m(2) for the Cockcroft-Gault equation and the re-expressed 4-variable MDRD equation, P=0.04 for both; 11.6 mL/minute/1.73 m(2) for the CKD-EPI creatinine equation, P=0.11), as the optimal scores of performance (6.0 versus a range from 1.0-2.0 for the other equations). Higher GFR category and diabetes were independent factors that negatively correlated with the accuracy of the CKD-EPI creatinine-cystatin C equation (β=-0.184 and -0.113, P<0.001 and P=0.02, respectively).
  
  
  CONCLUSIONS
  Compared with the creatinine-based equations, the CKD-EPI creatinine-cystatin C equation is more suitable for the elderly Chinese population. However, the cost-effectiveness of the CKD-EPI creatinine-cystatin C equation for clinical use should be considered.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, People's Republic of China ; College of Biology Engineering, South China University of Technology, Guangzhou, People's Republic of China.
authors.forename: Xun
authors.initials: X
authors.lastname: Liu
authors.forename: Huijuan
authors.initials: H
authors.lastname: Ma
authors.forename: Hui
authors.initials: H
authors.lastname: Huang
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Hua
authors.initials: H
authors.lastname: Tang
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Yanni
authors.initials: Y
authors.lastname: Wang
authors.forename: Tanqi
authors.initials: T
authors.lastname: Lou
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D055316:Cystatin C / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D016284:Technetium Tc 99m Pentetate
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate
keywords: cystatin C; elderly; equation; glomerular filtration rate; serum creatinine