title: The need for robust validation for MDRD-based glomerular filtration rate estimation in various CKD populations.
abstract: BACKGROUND
  Currently, estimated glomerular filtration rate (eGFR) equations have been validated only in Caucasians and African-Americans and is not applicable to people of other races/ethnicities as shown in studies conducted in two Asian populations: Chinese and Japanese. Because of this, it is important that eGFR equations are validated in its prospective population before applying it in the clinical setting and in epidemiologic studies. Therefore, we examined all eGFR equations available: reexpressed isotope dilution mass spectroscopy (IDMS)-traceable Modification of Diet in Renal Disease (MDRD) equation, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, Chinese equation and Japanese equation.
  
  
  METHODS
  A total of 350 adult Thai CKD patients were studied. The (99m)Tc-DTPA plasma clearance was used as a reference for glomerular filtration rate (GFR). The serum creatinine was determined by IDMS reference enzymatic methods (Cr(Enz)) and Jaffe's kinetic assay (Cr(Jaffe)) as indicated in each equation.
  
  
  RESULTS
  The disagreement between the reference GFR and eGFR (reference GFR minus eGFR) was 9.6 mL/min/1.73 m(2) for the reexpressed IDMS-traceable MDRD equation, 8.0 mL/min/1.73 m(2) for CKD-EPI equation, 1.9 mL/min/1.73 m(2) for eGFR equation from the Chinese study and 20.9 mL/min/1.73 m(2) for the eGFR equation from the Japanese study. The Thai coefficient for the reexpressed MDRD was 1.129. The reexpressed MDRD equation for Thais is as follows: 175 × Cr(Enz) ((-1.154)) × Age ((-0.203)) × 0.742 (if female) × 1.129 (if Thai). When stepwise multiple regression analysis was used, the Thai eGFR formula is: 375.5 × Cr(Enz) ((-0.848)) × Age ((-0.364)) × 0.712 (if female).
  
  
  CONCLUSIONS
  Differences in race/ethnicity can significantly affect the results obtained from MDRD-based eGFR equation. It is highly recommended that each population should validate eGFR equations before applying the equation in epidemiologic studies or clinical use.
authors.affiliation: Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand. kearkiat@hotmail.com
authors.forename: Kearkiat
authors.initials: K
authors.lastname: Praditpornsilpa
authors.forename: Natavudh
authors.initials: N
authors.lastname: Townamchai
authors.forename: Tawatchai
authors.initials: T
authors.lastname: Chaiwatanarat
authors.forename: Khajohn
authors.initials: K
authors.lastname: Tiranathanagul
authors.forename: Pisut
authors.initials: P
authors.lastname: Katawatin
authors.forename: Paweena
authors.initials: P
authors.lastname: Susantitaphong
authors.forename: Thananda
authors.initials: T
authors.lastname: Trakarnvanich
authors.forename: Talerngsak
authors.initials: T
authors.lastname: Kanjanabuch
authors.forename: Yingyos
authors.initials: Y
authors.lastname: Avihingsanon
authors.forename: Kriang
authors.initials: K
authors.lastname: Tungsanga
authors.forename: Somchai
authors.initials: S
authors.lastname: Eiam-Ong
mesh_terms: D000328:Adult; D000465:Algorithms; D044466:Asian People; D002138:Calibration; D003404:Creatinine / Q000097:blood; D004032:Diet; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis* / Q000453:epidemiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D016284:Technetium Tc 99m Pentetate; D013785:Thailand / Q000453:epidemiology
chemical_list: D003404:Creatinine; D016284:Technetium Tc 99m Pentetate