title: Accuracy to estimate rates of decline in glomerular filtration rate in renal transplant patients.
abstract: BACKGROUND
  We examined the use of the Cockroft Gault (C-G) test, Modified Diet in Renal Disease 2 (MDRD2) test, and inverse serum creatinine (Delta1/Scr) to estimate rates of decline in renal transplant function using isotope glomerular filtration rate (GFR) as a reference test.
  
  
  METHODS
  Percent changes in estimated GFR (DeltaeGFR) were compared to simultaneous changes in isotope GFR (DeltaiGFR) in 72 patients.
  
  
  RESULTS
  The number of iGFR was 508 with a mean of 7.15+/-3.15 scans per patient. There was a decline in iGFR of 16.14+/-21.37 ml/min over the study duration of 88.9+/-57.6 months. DeltaeGFR and Delta1/Scr correlated significantly with DeltaiGFR. Accuracy to predict DeltaiGFR from the eGFRs was limited to <65% concordance within 30% range from changes in iGFR. Slope analyses showed a significantly lower percent annual loss in mean iGFR of 6.03% than that of the C-G of 8.62% and MDRD2 of 8.96% (P<0.001). The within patient variability measured from the standard deviation (ml/min) of root mean square of 4.69 for iGFR was significantly higher than that for C-G and MDRD2 of 2.46 and 2.94, respectively. iGFR and eGFR at first observation correlated significantly (P<0.001) with last observation.
  
  
  CONCLUSIONS
  iGFR is significantly more variable within patient than the other predictors, and the two estimators predict the iGFR with a high sensitivity but low specificity. This is a clinically reasonable combination. Predicted percent of annual loss in iGFR appears to be smaller than that using the two estimators.
authors: Department of Community Health and Epidemiology, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK, Canada.
authors: Mohammad Akhtar
authors: MA
authors: Hossain
authors: Ahmed
authors: A
authors: Zahran
authors: Mahmoud
authors: M
authors: Emara
authors: Ahmed
authors: A
authors: Shoker
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006085:Graft Survival / Q000502:physiology; D006801:Humans; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016284:Technetium Tc 99m Pentetate
chemical_list: D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate