Table 3. Analysis of CG versus MDRD prediction equations stratified by type of GFR study (125I-Iothalamate or 99mTc-DTPA)

Mean CrCl/GFRa (Range)Mean Absolute DifferenceMedian Absolute DifferenceMedian % Absolute DifferenceBiasbR2c (Precision)Pearson CorrelationAccuracy % within
30%50%
a Mean calculated CrCl or GFR expressed as mean ± SD (range).
b Bias is the mean prediction error:where pei = predicted value - true value and N = sample size.
c R2 statistic was derived by simple linear regression and reflects the predictive ability of the model.
d Adjusted for BSA of 1.73 m2.
e Expressed as mL/min per 1.73 m2.
125I-Iothalamate
    Measured102.8 ± 15.7
(70–151.9)
    CGd108.3 ± 25.142.733.133%25.60.040.1345%73%
(57.8–169.4)
    CG-GFRd107.8 ± 42.133.828.625%5.00.050.1356%78%
(42.1–225.2)
    MDRD 1e102.3 ± 25.933.828.725%−0.50.150.2778%96%
(55.8–201.2)
    MDRD 2e99.4 ± 25.520.518.517%−3.30.140.2278%95%
(50.3–184.9)
99mTc-DTPA
    Measured125.0 ± 20.3
(77–169)
    CGd106.5 ± 33.031.622.019%6.00.180.4173%87%
(63.8–259.2)
    CG-GFRd110.1 ± 40.031.731.125%−15.00.210.4262%89%
(48.0–242.3)
    MDRD 1e91.9 ± 22.831.831.125%−33.20.400.4558%96%
(60.1–172.2)
    MDRD 2e88.5 ± 23.238.838.232%−36.50.380.4349%96%
(52.9–167.2)