Accuracy to estimate rates of decline in glomerular filtration rate in renal transplant patients.
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.
Hossain
Mohammad Akhtar
MA
Department of Community Health and Epidemiology, University of Saskatchewan, 103 Hospital Drive, Saskatoon, SK, Canada.
Zahran
Ahmed
A
Emara
Mahmoud
M
Shoker
Ahmed
A
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
D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate