A comparison of the predictive performance of different methods of kidney function estimation in a well-characterized HIV-infected population.
BACKGROUND
Glomerular filtration rate (GFR) estimation equations have never been validated in the HIV population. This pilot study aimed to compare all currently available methods of kidney function assessment with nuclear GFR in HIV-infected adults.


METHODS
Patients underwent GFR measurement with (99m)Tc-diethylenetriaminepentaacetic acid (Tc-99m Pentetate), and measured values were compared with results of creatinine-based estimation equations [abbreviated 4-variable Modification of Diet in Renal Disease (MDRD) formula and Cockcroft-Gault (CG) formulae], 24-hour urine creatinine clearance and estimated cystatin C GFR.


RESULTS
Twenty-seven HIV-infected adults were studied. Most were male and Caucasian, with a mean age of 52 years. Median CD4 was 290 cells/mm(3), 70% of patients had HIV RNA <50 copies/ml and all were receiving highly active antiretroviral therapy (median 5 drugs). Median Tc-99m Pentetate-GFR was 91 ml/min/1.73 m(2). Despite greater bias and similar accuracy, the MDRD formula was more precise than the CG formula, regardless of whether CG estimations were corrected for ideal body weight or body surface area. Relative accuracy within 30% of nuclear GFR was greater for the MDRD formula than for all other methods. The performance of 24-hour urine creatinine clearance was similar to that of the MDRD formula for patients with GFR <90 ml/min/1.73 m(2), although it performed less well at higher GFR. The performance of cystatin C GFR was inferior to that of all the creatinine-based methods.


CONCLUSIONS
While no method of kidney function estimation performed highly, both 24-hour urine creatinine clearance and the MDRD formula performed with a level of precision and accuracy sufficient for clinical decision making. Our findings support the preferential use of the MDRD formula in the treated HIV population and suggest that there are no HIV-specific factors that limit equation applicability. Larger validation studies are needed to confirm our findings and allow generalization to the HIV population at large.
Barraclough
Katherine
K
Division of Nephrology, University of British Columbia, Vancouver, B.C., Canada. arbieb@hotmail.com
Er
Lee
L
Ng
Francisco
F
Harris
Marianne
M
Montaner
Julio
J
Levin
Adeera
A
D000328:Adult; D000368:Aged; D000465:Algorithms; D023241:Antiretroviral Therapy, Highly Active; D001830:Body Surface Area; D001835:Body Weight; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D015658:HIV Infections / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging / Q000503:physiopathology*; D007677:Kidney Function Tests; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D016284:Technetium Tc 99m Pentetate
D055316:Cystatin C; D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate