title: Validation of the CKD-EPI formula in patients after renal transplantation.
abstract: BACKGROUND
  Accurate calculation of glomerular filtration rate (GFR) is crucial in the management of patients after kidney transplantation (KTx). Recently, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula was introduced to estimate GFR in chronic kidney disease patients. However, to date the diagnostic value of this equation remains to be determined in patients after KTx.
  
  
  METHODS
  We analysed the CKD-EPI formula in comparison to the re-expressed Modification of Diet in Renal Disease (MDRD) equation in 170 stable patients after renal transplantation. Correlation, bias, precision and accuracy within 30 and 50% of true GFR were determined. GFR was measured by technetium-diethylenetriamine pentaacetic acid clearance [39.6, 95% confidence interval (CI): 37.3-42.0 mL/min/1.73m(2)].
  
  
  RESULTS
  The results for the MDRD and CKD-EPI equations correlated well with GFR (0.82; 0.83, respectively). GFR calculated by MDRD (44.1, 95% CI: 41.6-46.8 mL/min/1.73m(2)) and CKD-EPI (47.7, 95% CI: 44.7-50.7 mL/min/1.73m(2)) overestimated true GFR significantly (P < 0.001). Precision was not significantly different between MDRD and CKD-EPI (10.9 versus 10.0 mL/min/1.73m(2), respectively). Accuracy within 30% of true GFR was significantly higher for MDRD (71.8%) than for CKD-EPI (64.1%, P = 0.0014). Accuracy within 50% of true GFR did not differ significantly (MDRD: 89.4% versus CKD-EPI: 84.7%, P = 0.06).
  
  
  CONCLUSIONS
  The new CKD-EPI formula did not improve the estimation of GFR in Caucasian patients after renal transplantation in this study.
authors.affiliation: Department of Internal Medicine I, University of Bonn, Bonn, Germany. dr.poege@nephrologie-bonn.de
authors.forename: Uwe
authors.initials: U
authors.lastname: Pöge
authors.forename: Thomas
authors.initials: T
authors.lastname: Gerhardt
authors.forename: Birgit
authors.initials: B
authors.lastname: Stoffel-Wagner
authors.forename: Tilman
authors.initials: T
authors.lastname: Sauerbruch
authors.forename: Rainer P
authors.initials: RP
authors.lastname: Woitas
mesh_terms: D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods / Q000592:standards; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies