title: Call for the use of a common equation for glomerular filtration rate estimation in East and South-East Asia.
abstract: BACKGROUND
  Estimated glomerular filtration rate (eGFR) is currently calculated using various equations and serum creatinine (Scr) value measured by different assays. Differences among these eGFRs deserve further study.
  
  
  METHODS
  Volunteers from eight Asian regions (n=3283; age 20-65 years, 1454 men, 1829 women) were recruited. The Chronic Kidney Disease Epidemiology Collaboration equation (EPI), Modification of Diet in Renal Disease Study equation (MDRD) for Japanese (MDRDJap) and MDRD for Chinese (MDRDChi) were selected. Jaffe and enzymatic assays were used to measure Scr. Six eGFRs were obtained for each volunteer: EPI equation using Scr value of enzymatic assay (EPI/E) and Jaffe assay (EPI/J); MDRDJap equation using Scr value of the two assays (MDRDJap/E, MDRDJap/J); and MDRDChi equation using Scr value of the two assays (MDRDChi/E, MDRDChi/J).
  
  
  RESULTS
  Neither Scr nor eGFR showed significant regional difference. We compared eGFR calculated using the same equation but with different assays. The medians (2.5%, 97.5%) of eGFR difference were 2.0 (-7, 14) mL/min/1.73 m(2) for EPI, 3.0 (-12.0, 18.0) mL/min/1.73 m(2) for MDRDJap, and 5.0 (-18, 30) mL/min/1.73 m(2) for MDRDChi. We also compared eGFR calculated using different equations but with the same assay. The medians (2.5%, 97.5%) of eGFR difference were 11 (-6, 56) mL/min/1.73 m(2) between MDRDChi/E and EPI/E; 26 (9, 35) mL/min/1.73 m(2) between EPI/E and MDRDJap/E; and 39 (22, 65) mL/min/1.73 m(2) between MDRDChi/E and MDRDJap/E, respectively.
  
  
  CONCLUSIONS
  eGFR difference caused by using different equations is much larger than that caused by using different Scr assays. A common equation for GFR estimation is encouraged for use in Asians.
authors.affiliation: Clinical Laboratory, Peking University First Hospital, Beijing, China.
authors.forename: Xuejing
authors.initials: X
authors.lastname: Wang
authors.affiliation: Faculty of Health Sciences, Yamaguchi University Graduate School of Medicine, Ube, Japan. Electronic address: ichihara@yamaguchi-u.ac.jp.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ichihara
authors.affiliation: Clinical Laboratory, Peking University First Hospital, Beijing, China.
authors.forename: Guobin
authors.initials: G
authors.lastname: Xu
authors.affiliation: Clinical Laboratory, Asahikawa Medical College, Asahikawa, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Itoh
mesh_terms: D000328:Adult; D000368:Aged; D001208:Asia; D044466:Asian People; D003404:Creatinine / Q000097:blood; D057075:Enzyme Assays / Q000379:methods; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007674:Kidney Diseases / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D003404:Creatinine
keywords: Chronic kidney disease; Creatinine; Equation; Ethnicity; Glomerular filtration rate