Table 4.

Association between predictor variables and measured GFR at each annual visit with the same multivariable regression model used for the MDRD equationa

Predictor% Difference in Standardized Iothalamate Clearance(95% CI)MDRD Equation (4)
BaselineFollow-Up Visit 1Follow-Up Visit 2Follow-Up Visit 3
SCr (per 50% increase)−22.0%(−26.1 to −17.6%)−31.8%(−35.1 to −28.3%)−32.7%(−35.8 to −29.4%)−32.5%(−35.5 to −29.3%)−37%
Age (per 50% increase)−5.4%(−8.9 to −1.9%)−2.1%(−5.7 to 1.6%)−6.2%(−10.4 to −1.9%)−5.6%(−9.8 to −1.1%)−7.9%
Gender
    female−9.4%(−14.6 to −4.0%)−18.4%(−23.0 to −13.4%)−18.4%(−23.2 to −13.3%)−24.2%(−28.7 to −19.4%)−26%
    maleReferenceReferenceReferenceReferenceReference
Race
    black3.7%(−4.7 to 13.0%)8.0%(−0.7 to 17.5%)9.3%(−1.3 to 21.1%)10.4%(−0.4 to 22.5%)21%
    otherReferenceReferenceReferenceReferenceReference
Model fit (logarithmic R2)0.4030.5790.6460.671
  • a Model also adjusted for study site. Results were similar when limited to patients who completed all four clinic visits(n = 192).\