Comparison of glomerular filtration rate estimates vs. 24-h creatinine clearance in HIV-positive patients

Guidelines for kidney function monitoring and antiretroviral drug dosing are available and respectively refer to glomerular filtration rate and creatinine clearance (CrCl).

The aim of the study was to compare kidney function estimates vs. measured 24-h CrCl in HIV-infected subjects.

A cross-sectional design was used, with comparison of Cockcroft-Gault (CG), original and simplified modification of diet in renal disease (MDRD) equations vs. measured 24-h CrCl. Subjects were HIV-infected, 18-70 years old, without pre-existing kidney disease.

Results are presented as mean (+/-standard deviation), unless otherwise stated. The study population consisted of 90 patients, of whom 71% were male, with a mean age of 45 years (+/-6.5 years). At the time of evaluation, the mean body mass index was 23 (+/-3.3); mean serum creatinine was 0.91 mg/dL (+/-0.2 mg/dL); and mean blood urea nitrogen (BUN) was 34.7 mg/dL (+/-10.6 mg/dL). Differences between paired methods were all significant (P<0.00001), except between CG and simplified MDRD (P=0.21; Pearson r=0.81). In univariate analysis, male gender, CD4 nadir, hepatitis B virus coinfection, BUN and current CD4 cell count showed a significant positive correlation (P<0.2) with the difference between measured 24-h CrCl and either CG or simplified MDRD estimates. In multivariate analysis, only BUN showed a significant positive correlation (P<0.05).

Estimates were lower than the measurements of 24-h CrCl. Original MDRD estimates were lower than those with other equations. CG and simplified MDRD estimates showed a satisfactory correlation.